PURPOSE
This document has been prepared by the state staff of the Uniform Dwelling Code (UDC) Program. In
the printed version, the first part contains the full Uniform Dwelling Code, which is followed by the
commentary. It is intended to assist users in uniformly applying the UDC, chs. Comm 20-25. If you have
comments or suggestions for this document, please contact us at:
Division of Safety and Buildings
Uniform Dwelling Code Program
P.O. Box 2658
Madison, WI 53707
(608) 267-5113
email: udctech@commerce.state.wi.us
fax: (608)283-7409
For general questions about the Uniform Dwelling Code, contact your municipal building inspection
department.
Copies of the Uniform Dwelling Code itself may be obtained for $21.00 (prices are subject to change
each January 1. In addition to the actual cost, state and county tax needs to be added.) from:
Wisconsin Department of Administration
Document Sales Unit
P.O. Box 7840
Madison, WI 53707
Telephone: (608) 266-3358 (800) 362-7253
The codes are also available on the Internet for free viewing, downloading and printing at
www.legis.state.wi.us/rsb/code/
Portions of this commentary may be superseded by subsequent changes in the code. This commentary is
relevant to the UDC as revised effective April 1, 2009. Printed copies of this may be purchased from
State Document Sales – see contact information above.
For updates, watch our agency website: www.commerce. state.wi.us/sb or subscribe there to our email
listservice.
This commentary is generally organized by code chapter and section, parallel to the code. Pages are
numbered with the commentary edition year first, chapter number next and page number for that chapter
last, as for example 2001-20-1. In addition, there are introductory sections at the beginning of the book
and each chapter and an inspection checklist at the end of the book.
i
State of Wisconsin
Department of Administration
Bureau of Document Services
Document Sales and Distribution
PO Box 7840
Madison, WI 53707-7840
docsales@doa.state.wi.us
www.doa.state.wi.us/section.asp?linkid=1
DOA-3330 (R12/2002)
UDC Document Sales Order
For Ordering Enforcement Materials for the Uniform
Dwelling Code Only
Ordered By: __________________________________________________
To Order:
For further information, please call (608) 266-3358
Organization’s Name: __________________________________________
Tax-Exempt Local Government (If Payer)
FAX: (608) 261-8150
Street Address: _______________________________________________
Check or money order must be made payable to:
WI Department of Administration
P. O. Box: ___________________________________________________
Open Monday through Friday, 7:45 am to 4:30 p.m.
Inter-D Address: DOA / 202 S. Thornton Ave / (name) /
DocSales /
City, State and ZIP + 4: _________________________________________
Daytime Telephone: _(_______)__________________________________
E-mail Address: _______________________________________________
Stock
Description
Item Price
Number Quantity
SBD-9494UDC Building Permit Seal – Single - Nontaxed
$33.00
SBD-9494UDC Building Permit Seal – 5 Pack – Nontaxed
$153.00
SBD-9494UDC Building Permit Seal – 10 Pack - Nontaxed
$303.00
SBD-9494UDC Building Permit Seal – 25 Pack - Nontaxed
$753.00
Non-Taxable Item Subtotal
SBD-5823
Wisconsin Uniform Building Permit Application – 25
$7.00
SBD-5824
Wisconsin Uniform Building Permit Card – 25 Pack
$7.00
SBD-6025
Inspection, Noncompliance & Final Report – 25 Pack
$7.00
SBD-6072
Permit to Start Construction – 25 Pack
$7.00
SBDNotice of Violation Card – 25 Pack
$17.00
SBD-7955
UDC Informational Brochure for Homeowners – 25
$7.00
SBDCommercial Building Code Info. Brochure – 25 Pack
$7.00
State Government Customers Only
Customer Use Code
Optional Data
Optional Order Number
Authorized Signature:
Credit Card Customers
Long Distance: 1-800-DOC SALE (362-7253) Local: 266-3358
Orders by phone are accepted when purchases are
made with VISA or MasterCard
Include credit card account number, signature, and
credit card expiration date.
MasterCard
VISA
Credit Card Number
Sales Tax
Unless
TaxExempt
Total
Taxable Item Subtotal
Add 5% state sales tax (WI residents only)
Add 0.5% WI county sales tax if applicable
Add 0.1% or 0.5% stadium tax if applicable
Total of Non-Taxable & Taxable Items
and
Taxes
Your order is subject to return if
there
are errors on
the order form and/or an incorrect amount due was
submitted. Please, call for assistance at (608) 2663358.
For Office Use Only
Date (mm/dd/ccyy)
CSR
Order No.
Customer No.
Approval No.
New Exp. Date (mm/dd/ccyy)
Amount Paid
Expiration Date (mm/dd/ccyy)
Signature
Payment Type
CA
CH
V/MC
GSBS
FR
This form can be made available in accessible formats to qualified individuals with disabilities. This order form may be reproduced.
ii
ADMINISTRATIVE CODE FORMAT
The Commercial Building Code, like other administrative codes, is divided into sections and
sometimes subchapters. Subchapters are used to help organize the code, while the sections
establish the specific requirements to be followed. Subchapters are for quick and easy reference
and do not need to be cited in written references. The first digit of each section number
corresponds to the subchapter it is in. Each subchapter and section has been given a title to
indicate what is covered within the subchapter or section.
Each chapter of administrative rules is divided into sections, subsections, paragraphs,
subdivisions, and subparagraphs. The sections are numbered according to the decimal system.
Following is a figure illustrating the different parts of a rule. The abbreviations shown in the
figure are used in the text of the rules when a reference is made. When you cite a specific part of
a rule, the entire rule number and letter designation should be given so that the item can be
readily referred to.
Comm 20.
Chapter
(ch.)
21
(1)
(d)
1.
b.
Section
(s.)
Subsection
(sub.)
Paragraph
(par.)
Subdivision
(subd.)
Subparagraph
(subpar.)
This can also be read as "Section 20 point 21, paren 1, paren d, 1 point, b point" and written as
s. Comm 20.21(1)(d)1.b. Multiple code section references are preceded by the abbreviation "ss."
"Comm" refers to Department of Commercethe name of the state department that formerly
enforced this and similar codes. Some older codes administered by this department have an
"IND" and “ILHR” prefix, which stood for Industrial Commission and Industry, Labor and
Human Relations, our governmental predecessor.
This can also be read as 50 point 21, paren 1, paren d, 1 period, b period and written as s. Comm
50.21(1)(d)1.b.. "Comm" refers to the Department of Commerce - the name of the state
department that enforces this and similar codes. Some older codes administered by this
department have an "ILHR" pefix which stood for the Department of Industry, Labor and Human
Relations or "IND" prefix, which stood for Industrial Commission, our governmental
predecessor.
A code reference that includes “(5m)” indicates that a new subdivision has been inserted into an
existing series between (5) and (6). A code reference that includes “51.275” indicates that a new
code section has been inserted into an existing series between 51.27 and 51.28 - in other words,
the third code section number acts as a decimal place.
iii
Multiple code section references are preceded by the abbreviation “ss”.
The fine print notes following various code sections are not enforceable parts of the code, but
rather are for informational purposes. This also applies to Appendix material. However,
footnotes to code tables are part of the code and are enforceable.
Many code sections will begin with a general statement and then follow with one or more
exceptions. Always check the exceptions. Also, many code sections will use special terms
which are defined in special definitions sections, the major one being s. Comm 51.01.
Note that there is a table of contents at the beginning of the code and each chapter and an index
at the end of the code.
In the official code, there is a register date at the bottom outside corner indicating the month of
issuance for that page. There are also history notes at the end of each numbered code section that
summarizes their revision history. Note that when new pages are issued, a revised code section
will have a new bolded history note entry. Also be aware that when a full page-width table
appears, it acts as a complete break in the dual-column text.
iv
WISCONSIN’S UNIFORM DWELLING CODE (UDC) - Some Basic Information
The statewide code for newer homes in Wisconsin is the Uniform Dwelling Code (UDC), Chs. Comm 20-25 of
the Wisconsin Administrative Code and its adopted references. It is a uniform building code that replaces
numerous local or non-existent building codes for new homes. Municipalities may not adopt a more or less
stringent code. The UDC was developed and is updated with input from a citizens’ Dwelling Code Council.
The UDC is principally enforced by municipal building inspection departments. The Wisconsin Division of
Safety and Buildings facilitates uniformity of its enforcement through code development, code interpretations,
special investigations, inspector training and certification, processing of petitions for variance and monitoring
manufactured dwelling firms.
PURPOSE AND SCOPE OF THE UDC
Q. What is the purpose of the UDC?
A. The UDC is a uniform statewide code that sets minimum standards for fire safety; structural strength;
energy conservation; erosion control; heating, plumbing and electrical systems; and general health and
safety in new dwellings.
Q. What buildings are covered by the UDC?
A. Basically it covers new one- and two-family dwellings built since June 1, 1980 and their additions and
alterations.* This includes:
• Seasonal and recreational dwellings (Electrical, heating or plumbing systems are not required, but if
installed they shall comply with the applicable codes. If a home is heated, then it shall be insulated.
Local sanitary requirements may require certain plumbing systems.)
• One- and two-family condominium buildings.
• A single-family residence connected to a commercial occupancy.
• Community-based residential facilities with up to 8 residents.
• Manufactured, modular or panelized dwellings regulated by the State (but not mobile or manufactured
homes regulated by the Federal Government).
• Additions to mobile or manufactured homes produced after June 1, 1980.
• A non-residential building, such as a barn, that is converted to a dwelling.
Q. What structures are not covered by the UDC?
A. The following are not covered:
• Dwellings built before June 1, 1980 or additions and alterations to such dwellings.
• Mobile (manufactured) homes which are instead subject to Federal standards.
• Multi-unit (three or more) residential buildings which are regulated by the State Commercial Building
Codes.
• Detached garages or accessory buildings.
Q. What about homes built before June 1, 1980?
A. The State does not have a construction or heating code for older homes or any accessory structures or
outbuildings. However, the State Plumbing and Electrical Codes and smoke detector codes do apply to all
dwellings, regardless of age.
For construction and heating standards for older homes, municipalities may adopt any or no code. Many
use the UDC. Others use the Wisconsin Uniform Building Code, which is not a State code but rather a
regional code in southeastern Wisconsin.
UDC ENFORCEMENT
Q. How is the UDC enforced?
A. The UDC is principally enforced by municipal or county building inspectors who must be state-certified.
They check for code compliance while construction is open for inspection. Municipalities of less than 2,500
population have the option of whether or not to enforce the code or to have the state provide enforcement.
To determine if there is state enforcement, contact the Division of Safety and Buildings (address at end of
brochure). In any case, state statutes require compliance with the UDC rules by owners and builders, even
where there is no local enforcement.
Q. What happens in municipalities without municipal enforcement?
A. If the municipality decides to have no enforcement of the UDC, then enforcement defaults to the state,
which will delegate enforcement to inspection agencies. See our website for details, including enforcement
statuses and inspection agency information.
v
BUILDING A UDC HOME
Q. What are the typical steps in building, adding onto or altering a code-complying home?
A. The steps to be taken by an owner or builder can be summarized as follows. (Some steps may not apply to
alterations or additions):
• Make initial contact with local zoning and building inspection departments to get an Energy Worksheet,
Building Permit Application, zoning rules and other basic information. Determine if your alteration
requires a permit or if you need your property surveyed.
• Design the home using standard design tables from the UDC or design a more customized home as
long as it is demonstrated that the design meets the general engineering standards of the code. In
addition to the UDC, the dwelling’s design may also be subject to subdivision rules or restrictive
covenants.
• Obtain sanitary or well permits from the county or municipality if the home will use a private sewage
system or well.
• Obtain floodplain, zoning and land use approvals from the county and municipality having authority.
• Obtain driveway or other local permits.
• Obtain any necessary utility approvals.
• Submit complete plans including plot, erosion control, foundation, floor layout(s), building crosssection(s) and exterior building wall views (elevations); Energy Worksheet; Permit Application; fees
and copies of the above permits to the municipal inspection department.
• Begin construction after plans are approved and building permit is issued and posted.
• Call for inspections of each phase of construction at least 2 business days prior to when work is to be
covered up (check the local inspector’s instructions). Inspectors will check for compliance with the
code. Cosmetic or non-code workmanship items will not normally be ordered corrected. However,
inspectors may also check that the approved plans are being followed, including items above the code
minimums. Deviations from the original plans may require submittal of revised plans.
• Take occupancy after receiving a final inspection in which no health or safety violations are found.
(Some municipalities will issue occupancy permits.) Also, the dwelling’s exterior must be completed
within two years after permit issuance.
• Correct any other code non-compliances, including stabilization by vegetation of any exposed soil.
Q. Who may do the work?
A. Following is a summary of applicable regulations:
• Anyone may design the home, other than for homes in a floodplain, which may require a registered
architect or engineer.
• The construction and erosion control permits must be taken out by a state-certified Dwelling Contractor
or by the owner who occupies the home currently or after completion. Note that State UDC Contractor
certification verifies general liability insurance only - it does not test the technical competency of the
builder. Each Dwelling Contractor must have a state-certified Dwelling Contractor Qualifier on staff.
• The plumbing work must be supervised by a master plumber and installed by licensed plumbers. (Only
after the dwelling is occupied, may an owner install additional plumbing beyond the pre-requisite
kitchen sink and full bathroom, unless prohibited by municipal ordinance.)
• All heating contractors must be state-registered. Owners working on their own property are exempted.
• Starting July 1, 2009, any contractor that is not otherwise certified, shall possess a Building Contractor
registration if performing work that is regulated by the Uniform Dwelling Code.
• Municipalities may have additional licensing requirements as well as bonding or insurance
requirements.
• In any case, we suggest that you:
• Check your contractors for proper liability and worker’s compensation insurance to minimize your
liability for injuries and damages to, or caused by, contractors.
• Check past customer references.
• Have a written contract.
• Obtain lien waivers from your subcontractors, so you are not financially responsible if your general
contractor fails to pay them.
Q. What could happen if the code is not followed?
A. Failure to comply with the code could cause the following:
• Endangering the health and safety of self, family or guests.
• Levying of fines and/or refusal to grant occupancy permit by local building inspection department.
• Civil action by owners against builders.
• Difficulty in selling the home.
• Civil action by future owners or tenants against original owners or builders. (The average home is
resold every 5 to 7 years.)
• Difficulty in obtaining mortgage loans or property insurance.
vi
•
Loss of building and community values.
Q. What if I am not able to exactly follow the Code?
A. If it would be difficult to comply with a particular code provision because of special site or design
considerations, then you may submit a petition for variance with the required fees to the State. Your
variance must show an equivalence to the code provision by different means. (Forms are available from
your local building inspector or the Safety and Buildings Division.)
Q. What if I have a problem with my home?
A. Every situation is different, but possible actions include:
• Contact the responsible general contractor and/or subcontractor for resolution. Note that the Right to
Cure law may require that you notify and give the contractor an opportunity to correct the problem prior
to commencing legal action or arbritation.
• Contact your homeowner’s warranty program, if applicable.
• Contact the local building inspector if the problems are code-related. (Note that orders may be written
against you as the owner.)
• Use the local homebuilder association’s arbitration services, if applicable.
• Obtain a consulting engineer or private building inspector’s report.
• Contact the Wisconsin Department of Agriculture, Trade and Consumer Protection (1-800-422-7128)
for alteration and addition problems.
• Use the small claims court system.
• Contact an independent mediation/arbitration service.
• Obtain a lawyer.
CODEBOOKS AND INFORMATION
Q. How do I get copies of the applicable codes?
A. Local zoning codes may be obtained from local government offices. The following State codes are needed
if you will be involved in the design and construction of a home:
• State Uniform Dwelling Code Chs. Comm 20-25
• State Plumbing Code Chs. Comm 82-87
• State Electrical Code Ch. Comm 16
These are available from:
State Document Sales
P O Box 7840
Madison, WI 53707
Before ordering, contact them at (608) 266-3358 to determine current fees which must be received with
your order. Telephone orders at 1-800-362-7253 are accepted when purchasing with a credit card. These
codes are available for free on line at: www.legis.state.wi.us/rsb/code An explanatory UDC Commentary is
also available for purchase.
In addition, the State Electrical Code adopts the National Electrical Code, available from:
National Fire Protection Association
One Batterymark Park
Quincy, MA 02269
Tel. 1-800-344-3555
Q. If I have further questions, who should I contact?
A. Again, the UDC is a locally enforced code, so contact the local municipal building inspection department
where the home will be built.
Otherwise you may contact:
Safety and Buildings Division
P. O. Box 2658
Madison, WI 53707
(608) 267-5113
or: www.commerce.state.wi.us
Fax: (608)283-7409
e-mail: udctech@commerce.state.wi.us
vii
Code or Statute Change Proposal
Division of
Safety and
Buildings
Wisconsin
Department of
Commerce
Type of change:
Code change
Statute change
Statute or code section no.
Topic
A.
Proposed change
B.
Justification: (Use reverse side, or attach a separate page.)
1.
Describe the problem this proposed change would address.
Include information to substantiate that a problem exists.
2.
What is the extent of the problem?
How often does it occur and who does it affect?
3.
What will happen if this change is not made?
4.
What costs, in terms of time and money, are associated with implementing this
change?
Name
Address
Do you wish to be part an email list of interested parties that will be created if and when a
code project begins?. If so, provide an email address here:
Telephone #
Date
Send proposals to Program Development Bureau PO Box 2689 Madison WI 53701-2689. For
more information, call 608-266-8741.
Personal information you provide may be used for secondary purposes. Privacy Law, s.15.04 (1) (m).
The Department of Commerce does not discriminate on the basis of disability in the provision of services or in employment. If you
need this printed material interpreted or in a different form, or if you need assistance in using this service, please contact us. TDD
608-264-8777.
SBD-10503 (R2/04)
viii
1.
Describe the problem this proposed change would address. Include information to substantiate
that a problem exists.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
2.
What is the extent of the problem? How often does it occur? Who does it affect?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
3.
What will happen if this change is not made?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
4.
What costs, in terms of time and money, are associated with implementing this change?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
ix
Agency Rule-Making Flow Diagram
Division forwards copy of
fiscal estimate to Financial
Management
Division drafts rule(s) in form required by
227.024, Stats.; prepares notice of public
hearing(s), rule report, and fiscal estimate as
required by 227.019, Stats.; completes
transmittal letter to Legislative Council;
forwards original and 2 copies to Secretary’s
office
Secretary dates and signs transmittal letter to Legislative
Council and forwards it, together with rule(s), rule report
and fiscal estimate for review to Leg. Council and JCBAR
Secretary forwards Notice of Public Hearings and fiscal estimates to
Revisor of Statutes. Schedule hearings for minimum of 40 working
days after receipt of rules by Legislative Council
Secretary forwards signed copy of
fiscal estimate to DOA
Legislative Council returns Clearinghouse Report for agency
review
Secretary forwards Notice of
Public Hearing and rules to
members of Legislature
requesting notice per 227.021
(1) (b), Stats.
Agency conducts public hearing(s)
Agency modifies rule(s) based on public hearing comments
and/or Legislative Council recommendations
Prepare final report*, which
includes:
1. Rule Report
2. Hearing Attendance Record
Form(s)
3. Hearing Comment & Agency
Response(s)
4. Response to Legislative Council
Rules Clearinghouse Report
Prepare implementation report for
JCBAR
Agency prepares rule(s) in final draft form
Agency prepares and inserts in each jacket, the following
materials:
1. Transmittal letter to chief clerk
2. Transmittal letter to presiding officer
3. Waiver of authority letter
4. Final draft form of rules (3 copies)
5. Final report* (1 copy)
Forward Assembly & Senate jackets and 1 copy of material
to Secretary’s office
Prepare revised fiscal estimate,
if required, and forward copy
to Revisor of Statutes for
publication in Wisconsin
Administrative Register
Secretary signs, dates and forwards transmittal letters and
jacketed material to chief clerk of each house and forwards
1 copy to JCBAR with an implementation report
Chief clerks deliver material to presiding officers of both
houses
Within 7 days of receipt of material, presiding officers
forward material to appropriate standing committees
Standing committees waive
authority or time expires
Standing committee review period, 30 days min., 60 days
max., 10 days for modification review and approval
permitted
Division prepares order of
adoption and certification and
forwards original plus 3 copies to
Secretary. If division wants copies
of rules, complete printing
requisition form (AD-P 219) and
include with order of adoption and
certification
Standing committees object
Forwards to JCBAR for
30 days
JCBAR concurs
with agency
JCBAR objects
Bill introduced
Secretary adopts rules and
forwards rules, order of adoption
and certification to Revisor of
Statutes and Secretary of State
Bill fails
Rules published
x
Bill passed; rules
not promulgated
Uniform Dwelling Code Council
Decmber 2008
Dennis Bauer, McFarland, Remodeling Contractors
Jeffrey Bechard, Eau Claire, Labor
David Dolan-Wallace, Green Bay, Architect
Thomas Doleschy, Muskego, Chicago Regional Council of Carpenters
Dan Gorski, Madison, Contractor
Robert Jakel, Kaukauna, Public
Brian Juarez, Fort Atkinson, Inspector
Steve Levine, Madison, Public
Frank Opatik, Wausau, Housing Manufacturer
Tom Palecek, Marshfield, Housing Manufacturer
Robert Premo, Hartland, Inspector
Gary Ruhl, Oshkosh, Labor
Mary Schroeder, Brookfield, Contractor
Kathleen Stadtherr, Green Bay, Inspector
William Turner, Hayward, Supplier
John Vande Castle, Fond du Lac, Supplier
Mike Wallace, Hudson, Inspector
xi
Notice of Changes to the Uniform Dwelling Code
(May 20, 2009)
The following is a summary of changes in the revised Uniform Dwelling Code (UDC), Chs. Comm 2025, effective April 1, 2009. The UDC is generally applicable to one- and two-family dwellings originally
built after June 1, 1980, except for energy requirements that began December 1, 1978. (Municipalities
may adopt the UDC or some other code to apply to alterations and additions to older dwellings.) These
changes have been reviewed and approved by the Dwelling Code Council, a governor-appointed advisory
council composed of builders, designers, code officials, labor representatives, subcontractors and others.
Refer to the official code for details of the code.
These code changes are applicable to permits applied for on, or after, April 1, 2009. Previously permitted
ongoing projects and existing dwellings not undergoing changes are not subject to these code revisions.
To be a valid permit application, any prerequisite approvals such as zoning or sanitary must first be
obtained and proper building plans and specifications must be provided to the municipal building
inspector. For further information, contact your municipal or state-assigned building inspector (see our
website, www.commerce.wi.gov/SB/SB-UDCProgram.html , for contact information).
To purchase a new codebook for $21 plus tax handling, contact State Document Sales, POB 7840,
Madison, WI, 53707, Tel. (800)362-7253. To also receive any upkeep code change pages for the next 12
months, there is an additional charge equal to the codebook price. (Attendees at this winter's building
inspector association/Dept. of Commerce sponsored inspector training sessions will receive a copy of the
unofficial code.)
The revised UDC code is also available on the Internet at www.legis.state.wi.us/rsb/ at no charge for
viewing, copying or printing. Other information on the new code is available at the Division of Safety &
Buildings' website at www.commerce.wi.gov/SB/SB-DivCodesListing.html .
In April 2009, the UDC Program will be offering for sale a Commentary with explanatory and
illustrative material for users to better understand the code. Check our website
www.commerce.wi.gov/SB/SB-UDCProgram.html for ordering information.
Notice of New Credentialing Requirement – The Department of Commerce has adopted an
emergency rule with an effective date of July 1, 2009 that will require most construction contractors
and subcontractors to hold a registration issued by our agency, unless they already hold a business
credential issued by us, such as the Dwelling Contractor credential. For further information, go to
our website, www.commerce.wi.gov/SB/SB-BuildingContractorProgram.html
Please share this information with your customers, staff, suppliers and subcontractors. Major code
changes are bolded.
Chapter Comm 20 – Administration & Enforcement
1.
20.02(1)(h) – Clarifies that the UDC applies to adjacent, unattached structures that serve as
an exit from a UDC-covered dwelling. Note that this is not applicable past the point where
the occupant has a code-compliant egress path to exterior grade.
xii
2.
3.
4.
20.04(5)(a) – Clarifies that the applicability of the UDC to a new foundation provided to an
existing dwelling is dependent on the original date of construction of the dwelling being after
June 1, 1980.
20.04(5)(b) – Clarifies that the current UDC applies to an existing foundation upon which a new
dwelling is placed.
20.04(6) – Clarifies that in order for two dwellings to be considered separate buildings, they
may not share more than footings and each dwelling shall have facing walls with their own
code-compliant insulation, exterior finish and fire-rating.
Non-structural flashing permitted
Dwelling Separations
Independent Roof Systems
Separate exterior
wall fire rated per s.
Comm 21.08 (1) and
insulated per ch. 22.
Detail A
Dwelling 3
(Single)
Dwelling 2
(Duplex)
Separate exterior
wall fire rated per
s. Comm 21.08 (1)
Separate exterior covering
meeting Comm 21.24
Separate exterior covering
meeting Comm 21.24
Independent Floor System
Dwelling 1
(Duplex)
Dwelling 2
Dwelling 1
(Duplex)
(Duplex)
Separate Insulated
Foundation Wall
Separate Insulated
Foundation Wall
Shared Footing OK
Detail A
5.
6.
7.
8.
20.05(6) – Clarifies that only those farm buildings not used for habitation are exempt from the
UDC.
20.05(9) - Exempts from the UDC, those motor homes and recreational vehicles that are, or
have been, titled by the Wisconsin Department of Transportation (DOT). Note that in
order to be titled by DOT, recreational vehicles require a towbar (hitch), chassis, axles and
wheels for transportation. At the installation site, the chassis and axles shall remain on the
unit, with the towbar (hitch) and wheels left at the site. Otherwise the unit, including a socalled park model, is subject to the UDC. Additionally, any additions, with a roof, to a
motor home or recreational vehicle are considered dwellings that shall comply with the
UDC.
20.065 - Codifies the Department of Commerce's statutory authority to monitor general
municipal enforcement and to audit municipal erosion control enforcement. The
Department may review the municipal building inspection records required by Comm
20.10(6) and report on their findings to the municipality.
20.07(5m) – Defines "attached", as applied to two structures, when there is either a
continuous weatherproof roof, continuous structural floor system or continuous foundation
between them.
xiii
Solid Roof
Covering over
Walkway
Dwelling
Garage
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Garage and walkway
part of the dwelling
and within the scope
of UDC
20.07(18) – Defines "common use area" to be kitchens, hallways, basements, garages and all
habitable rooms (bedrooms, dining rooms and living rooms) . Common use areas are required by
s. Comm 21.03(8) to have at least a 30" net clear opening or a 32" door leaf leading to it.
20.07(53f) – Creates new definition of "modular home" to replace the previous "manufactured
dwelling" term. This applies to factory-built homes that comply with the UDC, rather than the
federal HUD standards that are applicable to “manufactured homes”.
20.09(5)(b) – Requires that a heating distribution layout be provided on the floor plans. This
includes the location of the supply and return ducts in each space provided.
20.09(5)(b) – Requires that the location and construction details of the braced wall lines be
shown on the floor plans.
20.10(b)3. – Clarifies that construction may proceed without inspection after two business
days after the day of inspection request. Note that as before, the work must be in a
completed, ready-for-inspection condition at the time of inspection request or at a stated
later time, in which case, the clock begins at that later time.
20.10(3)(c) – Requires an inspection after excavation and placement of any footing forms,
required footing reinforcement or required drain tile bleeders, but prior to placing of any
concrete.
20.10(3)(d) – Requires that any required foundation reinforcement shall be inspected prior
to being covered, including, window headers, reinforced masonry walls and foundation
stepdowns. This is not applicable to reinforcement that is non-required reinforcement, such
as for shrinkage crack control. Note that some short-span foundation stepdowns, where the
foundation is unsupported by the earth for only several feet may not require reinforcement
based on arching action.
20.10(3)(f)1.a. – Requires a basement floor inspection after installation of the vapor
retarder and any required drain tiles or granular materials, but prior to pouring. Any
underfloor plumbing, electrical or HVAC work or insulation would also need to be
inspected prior to pour as required for rough or other inspections of those elements.
20.10(3)(h)2. – Clarifies that occupancy may take place without a final UDC inspection after the
fifth business day following the day of inspection request. Note that this ability to occupy
without a UDC inspection does not waive any other pre-occupancy requirements imposed by
local zoning, municipal utilities or other similar regulations.
20.21(1)(intro) – Clarifies that appeals to the Department of Commerce of municipal
actions shall first have exhausted municipal appeal procedures in order for the Department
to order the reversal of such a local action.
20.24 – Updates a number of adopted national technical standards to current editions.
xiv
Chapter 21 – Construction Standards
20. 21.02 (3) (a) Clarifies that all aspects of construction, including design and analysis, shall follow
the applicable national standards.
21. 21.02 (3) (b) 3. Incorporates language from the UDC Commentary permitting the use of specified
default grades for ungraded lumber for certain types of lumber uses. For example, the code
default for studs is No. 3 and No. 3 is better than stud grade required by code. There fore, an
ungraded 2 X 6 may be used as a wall stud.
22. 21.02(3)(e). Replaces reference from Concrete Masonry Handbook for Architects, Engineers,
Builders to masonry standards ACI 530 and 530.1 as adopted in Table 20.24-1.
23. 21.02 (3) (g) Addresses log home construction with two adopted national standards. (The ICC
standard is generally applicable to log structures, while the ILBA standard applies only to
construction using handcrafted, interlocking, scribe fit construction.)
24. 21.03 (1) (b) Clarifies that at least one exit must discharge to grade and cannot pass through a
garage. (At least one additional exit is required, but it can be a balcony or go through a garage,
etc.)
25. 21.03 (3) (b) Allows a single exit and egress window exiting from a small third floor nonsleeping "lookout room".
26. 21.03 (3) (c) Adds the option of sprinkler protection in lieu of a second exit from a third floor.
27. 21.03 (6) (e) 5. Adds specifications for ladders in basement exit areaways (window wells).
28. 21.035 (1) (c) 1. Clarifies that minimum doorway width applies to access to all fixtures of at least
one full bathroom. This includes the door of the bedroom if the bathroom is located within the
bedroom.
29. 21.035 (1) (c) 2. Requires that if there is a full bathroom on the first floor, then it shall have the
minimum doorway widths per this section.
30. 21.035 (2) Clarifies that up to 84" above the floor you may infringe 4 ½ inches maximum on both
sides into the 36” minimum width of a hallway. Higher than that, infringements are unlimited.
31. 21.035 (3) Adds a requirement for 30 inches of clearance between major appliances and
islands, walls or built-in cabinets. This is measured to the face of the cabinets, not including
countertop nosing.
Unregulated
Built-in
Cabinet
30”
Major
Appliance
Island
32. 21.04 (2) (c) Clarifies that a winder tread cannot be inserted into a straight stairway unless there
is a change in direction.
33. 21.04 (2) (e) 1. Changes the stairway uniformity requirement so the largest tread and riser
measurements cannot vary from the smallest measurements by more than 3/8 inch within a
flight. (A flight is a series of steps with landings at both ends.)
34. 21.04 (2) (g) Requires the walking surface of stair treads and landings to be free of excessive lips
and protrusions.
35. 21.04 (3) (a) 2. Adds a note to clarify that on an open-sided stairway, a handrail at 30-38 inches
above the nosing meets the height requirements for a guardrail.
xv
36. 21.04 (3) (a) 3. c. Requires non-rigid (cable and rope) handrail and guardrail infill to be strung
with maximum openings of 3.5 inches to address the flexibility of the infill.
37. 21.04 (3) (c) 1. b. Clarifies that guardrails, including structural infill, are required where
insect screens are the only means of fall protection.
38. 21.04 (3) (c) 1. c. Clarifies that the 24 inch vertical drop-off measurement that triggers
guardrails is taken from the lowest point within 3 feet horizontally of the edge of the
landing, deck, porch, etc.
If “X” is < 36”, and
“Y” is > 24”, then,
a guardrail is required on the
left-hand side of the landing.
“X”
“Y”
39. 21.05 (3) (intro) Modifies this section to reference the latest standard for safety glazing –
CPSC 16 CFR, part 1201, which means that most wired glass will not meet safety glazing
standards.
40. 21.05 (3) (a) Modifies the safety glazing requirements so that it is required for a sidelight or
glazing that is within 2 feet horizontally of the door and is within 5 feet of the floor and is in
a plane within 30 degrees of the plane of the closed door.
NO Safety Glaze
NO
Safety
Glaze
Safety
Glaze
NO
Safety
Glaze
Safety
Glaze
>30 degrees
from door
plane – NO
Safety Glaze
Safety Glaze
Safety
Glaze
5'
Door
2'
2'
xvi
< 30
degrees of
door plane
– Safety
Glaze
Window if
< 5’ above
floor and
within 2’
of door
41. 21.05 (3) (b) Expands the safety glazing requirement beyond the "tub or shower enclosure" for
any glazing within 3 feet of the inner rim of the tub or shower and 5 feet vertically from the drain.
<5'
<3'
Drain or
Bottom of Tub
<3’
42. 21.08 (1) (intro. & Table) Changes fire separation requirements for zero-lot line dwellings
to only require one shared wall rated for the equivalent of one hour.
43. 21.08 (1) (a) 4. Repeals the statement that adjoining garage units are not required to be separated
from each other. (In most cases this will still be acceptable, except where the dwelling unit
separation in a duplex is placed between adjoining garage units.)
44. 21.08 (1) (c) Adds requirements for glazing to be fire-rating listed when installed in the wall
between an attached garage and a dwelling.
45. 21.08 (1) (d) 1. Allows attic access openings in garages to be protected with a material with a
finish rating of 20 minutes or more. As before, it shall have hinges and a latch but not necessarily
a self-closer.
46. 21.08 (2) (b) Clarifies different types of attic separation.
Dwelling Unit separation
from foundation to roof
deck
Attic draft
stopping wall in
line with dwelling
unit separation
wall
5/8" gypsum wallboard or
equivalent on each side of
the wall
Duplex
Side one
Duplex
Side one
Duplex
Side two
METHOD #1
Comm 21.08 (2) (b) 1.
5/8-inch Type
"X" gypsum
wallboard on
ceiling
Dwelling Unit separation
from foundation to
ceiling
- 5/8" gypsum wallboard
or equivalent on each
side of the wall
Duplex
Side two
METHOD #2
Comm 21.08 (2) (b) 2
47. 21.08 (2) (d) Strengthens the wall separation requirements between dwelling units to
typically 5/8” drywall on both sides of the wall.
48. 21.08(f) The list of acceptable attic draft stopping materials has been changed to include 3/8-inch
wood structural panels or 1/2-inch gypsum board. Fiberglass insulation is no longer listed as an
acceptable attic draft stopping material.
49. 21.09 (1) (b) Clarifies that hallway smoke detectors have to be within 21 feet of the centerlines of
the served bedroom doors and have to be in the exit path.
xvii
50. 21.09 (2) Allows non-interconnected, battery-powered smoke detectors for dwellings with no
electrical service.
51. 21.095 Requires automatic fire sprinklers, if installed, to meet the NFPA 13D standard and adds a
state amendment allowing partial coverage, unless NFPA 13R sprinklers are provided per s.
Comm 21.03(3)(c)1.
52. 21.10 (1) to (4) Adds and clarifies requirements for treated wood.
53. 21.10 (5) Adds requirements for corrosion resistance of fasteners used with treated wood.
54. 21.15 (2) (a) Expands the note in this section to clarify the properties of an unstable soil for
purposes of unformed footings.
Trench
Trench
Stable Soil
Un-Stable Soil
(Must be Formed)
55. 21.16. Adds an exception to allow the use of a frost protected shallow foundation that is installed
in accordance with ASCE -32 as adopted in table Comm. 20.24-5. The Department also accepts
designs in accordance with the U.S. HUD “Design Guide for Frost-Protected Shallow
Foundations” available for free download from
www.huduser.org/publications/destech/desguide.html .
56. 21.17 (1) (b) 2. Adds a requirement that if a partial drain tile system is provided, it must
have a means to discharge water from the tile or pipe to a sump pit, a crock or daylight.
57. 21.17(3)(d) 1. Adds an exception for not providing exterior drain tiles around foundations
serving walkout basements.
58. 21.18 (1) (d) 2.b. Includes floor joist bridging, along with solid blocking, as a bracing means for
foundation walls that are parallel with the floor joists.
Joists
Diagonal Bracing OR
Blocking @ max 32"
o.c. spacing
59. 21.18 (3) (a). Requires an additional coat of dampproofing material over portland cement
parging option or equivalent system for masonry foundation walls.
60. 21.18 (4). Modifies this section to require wood foundations be designed to the latest AF&PA
standard as adopted in Table 20.24-2.
61. 21.18 (4). Adds a note that permits the use of the Permanent Wood Foundations Design and
Construction Guide published by the Southern Forest Products Association. This may be
downloaded at no charge at www.southernpine.com
62. 21.22 (3) (d). Clarifies that lateral restraint with a saddle or rigid connection is required for
beams that pass over columns if the beam is > 11.25” deep or is not restrained from rotation
xviii
on both ends. Also see s. Comm 21.25 (6) (a) 4. for positive connection requirements
between all beams and columns. This requirement also applies to decks that serve the
dwelling.
63. 21.22 (8) (b). Removes Table 21.22-C relating to plywood underlayment.
64. 21.24 (2). Codifies the requirement that doors and windows be in place prior to installation
of insulation during construction and adds that at least roof underlayment must also be in
place.
65. 21.24 (3) (c). Adds minimum lap of 6” for vertical and 2” for horizontal flashing and minimum
specifications for the sealant on the lap.
66. 21.24 (4). Adds minimum uniform requirements for a water resistive barrier on the
exterior walls of wood or metal frame construction from the highest point to the bottom of
the exterior weather-resistant covering, including gable ends. Manufacturers of exterior
coverings may have additional requirements.
67. 21.25 (6) (a) 4. Adds a new section requiring a positive connection between columns and
beams by means of clips, straps or saddles. If a rigid connection is not required by s. Comm
21.22 (3) (d), then clips, straps, screws or nails may be used to meet the positive connection
requirement of this section.
68. 21.25 (7). Adds a new section for the sizing and bracing of foundation cripple walls.
69. 21.25 (8) & (9). Expands bracing requirement for dwellings. In addition to requiring
bracing at the corners, bracing will be required at no more than 25 foot intervals in the
braced wall line and braced wall lines will need to be provided and spaced no more than 35
feet o.c. An exception is provided to permit the walls to be spaced up to 50 feet o.c. This
section also includes a note permitting the alternative use of wall bracing provisions, s.
R602.10, of the 2009 International Residential Code (IRC).
70. 21.26 (1). Specifies that cold weather work on masonry walls must conform to adopted standard
ACI 530.1.
xix
71. 21.26 (3) (a) and Tables 21.26-B1 & B. Adopts the requirements of ASTM C-270 for mortar
properties.
72. 21.26 (5) (a). Repeals and recreates this section to require corbels to be constructed in
accordance with ACI 530.
73. 21.26 (7) (a) 2. Adds a requirement that a minimum one-inch air space be provided
between masonry veneer and the sheathing unless a manufactured offset material is used.
74. 21.26 (7) (a) 5. Adds a requirement that ventilation openings be provided at the top of
masonry veneer walls.
75. 21.26 (7) (a) 6. Adds a requirement that studs and sheathing behind masonry veneer shall
be covered with a water-resistive barrier meeting s. Comm 21.24 (4).
76. 21.26 (7) (a) 7. Adds a requirement that masonry or brick veneer be placed above grade
unless other provisions specified in this section are met.
77. 21.26 (7) (c). Adds a requirement that masonry veneers be anchored in accordance with ACI 530
and ACI 30.1.
78. 21.26 (8). Adds new flashing and weep hole requirements including: Open joint or weep
hole spacing reduced from 3 feet to 2 feet. More clearly specifies the required location and
type of flashing. Requires that rope or similar material used to form the weep hole be
removed as soon as the mortar sets.
79. 21.26 (12). Modifies this section requiring joints in masonry construction to be constructed in
accordance with ACI 530.1.
80. 21.27. Adds a requirement, s. 21.27 (1) (b), that joist and rafter tables in the appendix are valid
for roof with a minimum slope of 3 in 12. Lesser slopes require engineering analysis or shall be
provided with a ridge beam. Anchorage requirements of old 21.02 (1) (c) 2. & 3 relocated to s.
21.27 (3) (b).
81. 21.28 (6). After reroofing, codifies a maximum of 2 layers of roofing.
82. 21.28 (7) (d) 3. Increases the flashing height requirements at the intersection of crickets and
chimneys from 4 inches to 6 inches.
83. 21.40 (2). Adds a minimum thickness of 4 inches for solid concrete cap blocks for manufactured
home piers.
Chapter Comm 22 – Energy Conservation
84. 22.01 – Clarifies that UDC energy provisions apply to equipment efficiency in all UDC
dwellings, even those with renewable energy and that vapor retarder & moisture control apply
when any insulation is present.
85. 22.20(6) – Requires that a permanent certificate of insulation R-values and fenestration Ufactors be provided on or next to the electrical distribution panel. This should be in place at
the time of the insulation inspection.
86. 22.21(2) – Adds cold-in-winter side windwash protection of air-permeable wall insulation where
exterior sheathing is not present, thus keeping insulation in place & maintaining insulation Rvalue.
87. 22.30 – Requires that a garage be insulated if heated, unless limited to 50o maximum temperature.
88. 22.31(1) & (3) – Adds new Tables 22.31-1 & 22.31-4 with revised R-values and U-factors.
Use Table 22.31-1 if higher efficiency HVAC equipment is used and Table 22.31-4, with
higher insulation levels, if normal efficiency HVAC equipment is used. Insulation is now
required under the entire slab where the slab is heated.
89. 22.31(2)(b) – Specifies edition of the REScheck software program to be version 4.1.0 or
newer, as earlier versions were based on less insulation and lower energy compliance
standards than the current code.
90. 22.35 – Reduces envelope insulation requirements for thermally isolated sunrooms.
xx
91. 22.36 – Exempts small amounts of fenestrations from minimum insulation requirements.
92. 22.37(4) – Adds maximum air leakage rates for recessed lighting.
93. 22.38 – Prohibits interior vapor retarders of 0.1 perm or less on concrete or masonry basement
walls.
94. 22.39 – Vented attics and condition attics are clarified. Dampers that close are needed on outdoor
intakes & exhausts for when the ventilation system is not operating. Clothes dryers shall be
vented outside the structure.
95. 22.42 – Requires duct system insulation of R-8 for areas outside of envelope.
96. 22.45 – Adds air conditioners and heat pumps minimum efficiencies.
97. 22.52 – Adds new documentation provisions, including the inspection checklist of the
components of that system, for simulated performance software programs.
Chapter Comm 23 – HVAC Standards
98. 23.02(3)(a)2. – Adds requirement for back-draft dampers on exterior intakes & exhausts.
99. 23.04(5) – Adds section regarding water heaters used for space heating purposes.
100. 23.08 – Table 23.08-B clarifies support of rigid ducts, including hanger options.
101. 23.09(1)(b) – Requires permanent access to the volume duct dampers for adjustment at a later
time.
Chapter Comm 24 – Electrical Standards
102. 2008 NEC will become effective in Wisconsin March 1, 2009. The requirements for the arc-fault
circuit-interupter protection and tamper-resistant recepticles in dwelling units have a delayed
effective date of January 1, 2010.
103. If footing or foundation rebar is provided, it must be used as a grounding means for the
electrical service. Foundation installers should provide grounding means such as an
exposed rebar stub.
Chapter Comm 25 – Plumbing Standards
104. New Plumbing code effective March 1, 2009
xxi
Chapter Comm 20
ADMINISTRATION AND ENFORCEMENT
Subchapter I  Purpose and Scope
20.01 Purpose
It should be kept in mind that statewide uniformity is a primary objective in the administration
and enforcement of the code. To accomplish this objective, it is important that any variations
in the regulations be kept at an absolute minimum and that persons given the responsibility to
interpret and enforce these regulations perform their duties the same as their fellow workers.
Therefore, the UDC is a maximum and minimum code and all inspectors enforcing it must be
state-certified. The UDC Program staff at Safety and Buildings Division act as consultants to
inspectors and other users of the code to help maintain this uniformity.
Question:
Answer:
What are the Wisconsin Uniform Building Code and International Residential
Code?
The Wisconsin Uniform Building Code (WUBC) was prepared by the Building
Inspectors Association of Southeastern Wisconsin. It was quite popular before
the state code, Comm 20-25 (UDC), was enacted in June 1980. Some
municipalities still use the WUBC code for outbuildings and pre-1980 dwelling
alterations and additions since such construction is not covered by the state UDC.
It also covers local administrative procedures and levying of fines which are not
covered by the UDC. The WUBC has a chapter numbering system starting with
30 which helps distinguish it from the UDC, chs. 20-25.
There is also a national model building code called the IRC (International
Residential Building Code) that is prevalent in some neighboring states including
Minnesota but is not enforced in Wisconsin.
20.02 Scope
The emphasis we should make in this paragraph is on the word "new." It is the intent of the code
that these regulations not apply, as far as the state is concerned, to any house constructed prior to
the effective date of the regulations. Chapter Comm 22 became effective December 1, 1978 and
Chapters Comm 20, 21, 23, 24 and 25 became effective June 1, 1980. Homes built prior to these
dates are not subject in any way to the Uniform Dwelling Code as far as the state is concerned.
Local regulations may be stricter and retroactively apply the UDC to such homes. The separate
state electrical and plumbing codes also applied before 1980. A separate state smoke detection
code, Comm 28, does apply to houses built before 1980.
The Department of Agriculture, Trade and Consumer Protection administers Chapter Ag 110,
Wisconsin Administrative Code, which regulates home improvement trade practices (but does
not cover construction of new residences). This code includes language regarding prohibited
trade practice, building permits, guarantees or warranties, home improvement contract
2009-20-1
20.02(1)
requirements and preservation of buyer's claims and defenses, but not bonding. Foundation
waterproofing contractors need to comply with ATCP 111.
For complaints about home improvement trade practices (not new home construction) or
landlord/tenant relations, you may contact:
Wisconsin Dept. Of Agriculture Trade & Consumer Protection
Trade And Consumer Protection Division
801 West Badger Road
P O Box 8911
Madison WI 53708
1 (800) 422-7128
20.02(1) Pre-UDC Dwellings
In the case of a burned or collapsed pre-UDC dwelling, a substantial portion of the dwelling that
encloses space, such as a basement with a floor deck above, must remain in order for a
reconstructed dwelling to be exempted from the UDC. Local regulations may be stricter by the
use of the raze and remove procedures of state statute s. 66.0413.
It needs to be emphasized that only pre-existing dwellings and dwelling units are exempted.
Buildings previously used for other purposes and converted to a dwelling are subject to the UDC
upon conversion to residential use.
Also, the use of used lumber and other materials from an old dwelling in a new dwelling does not
exempt it from the UDC.
20.02(1)(b)&(c) CBRF's or AFH's
Question: What constitutes a community-based residential facility (CBRF) or an Adult Family
Home (AFH) versus a rooming house?
Answer:
The key is that a CBRF or AFH must have a license issued by the state Department
of Health and Family Services (Tel 608-261-5993). The UDC covers those
facilities constructed since 1980 serving 3 to 8 clients. Staff people are not counted.
20.02(1)(h) Unattached, Adjacent Structures
This section applies the UDC to adjacent structures that are unattached to a dwelling but serve as
an exit to the dwelling. This application extends no further than to the point at which a person
arrives at grade and has free movement.
20.02(2) Municipal Ordinances
This requirement restricts the adoption of local ordinances which would be considered more or
less restrictive than the Uniform Dwelling Code. Also refer to subsection Comm 20.06(1).
Note that this section does allow municipalities to enforce occupancy requirements on a UDC
dwelling after the first occupancy. This would allow for housing ordinances that require basic
maintenance of the structure after the original construction.
-2004-20-2-
20.02(3)
20.02(2)(b) Allowable Municipal Ordinances
"Land use" would include regulating such things as locating a house in a farming or business
district.
"Zoning" ordinances are considered to be those which do not affect the design or assembly of a
house or its appurtenances. Allowable zoning issues can include minimum dwelling size,
exterior finish material, maximum dwelling height, minimum finished grade height and other
items relating to the exterior appearance of the dwelling or to community property values.
"Setback" - In addition to requiring minimum distances to lot lines, streets, other buildings, etc.
there could be a limitation on not permitting a building wall to have an opening if the wall is
within a prescribed distance from the property line. Also there may be requirements for requiring
a minimum fire-resistive rating for such a wall. This would be for the purpose of fire protection
of adjacent property. An example would be a local requirement for a firewall at the property line
of a "zero lot line" duplex.
"Hazards at the job site" means during the period a house is being constructed.
20.02(2)(c) Items Not Within the Scope of the Code
Municipalities may adopt local ordinances covering the following:
"Construction" - Detached buildings such as garages, storage, agricultural buildings, fences,
driveways, etc.
"Additions, alterations or repairs" - Additions, alterations and repairs to houses constructed
before June 1, 1980. However, additions, alterations or repairs to houses built between
December 1, 1978 and June 1, 1980, must comply with ch. Comm 22, Energy Conservation
requirements.
20.02(2)(c) Pre-1980 Dwellings
Municipalities may adopt any code, including the UDC, to apply to homes built before June 1,
1980. In fact, they are encouraged to adopt the UDC for these older homes, especially alterations
and additions, so as to simplify enforcement procedures and code understanding by builders and
owners. However, any petitions for variances on pre-1980 dwellings would be handled by the
local municipality only. Also, state inspector certification would not be necessary to enforce the
UDC on older homes.
However, the Wisconsin Uniform Plumbing and Electrical Codes generally do apply to all
buildings in the state, regardless of the age. Also, the Smoke Detectors Code, ch. Comm 28, will
require older dwellings to have smoke detectors, and the Rental Unit Energy Efficiency
Standards Code requires rental residential property to meet energy conservation standards at the
time of sale.
20.02(3) Legal Responsibility
-2004-20-3-
20.02(4)
The compliance and penalty sections of the statutes and code first require the owner, designer
and builder to conform to the law and the code even if there are no inspections performed. When
inspections are performed, the inspector is required by the same statute section to be certified. It
is the responsibility of everyone involved to carry his or her respective share of the liability of
complying with the laws and regulations. Governing bodies which perform inspections are
considered to be in a position of "conflict of interest" if they also perform acts of actual design
and physical construction of the inspected work. It is the duty of the governing bodies and
inspectors to advise, inspect and cause compliance. It is not their duty to perform design and
construction type activities. This is not to say that inspectors and their employing municipalities
are exempt from liability in their actions.
20.02(4) Retroactivity
The general rule is that for a regulation to be retroactive, it must be written with a statement that
existing conditions must be brought into conformance. As the UDC is revised and updated,
existing homes are not required to be brought up to the new standards. Because of this, it is
important that inspectors keep their old code books for use in inspecting existing dwellings.
A dwelling may continue to be built per the code at the time of permit application, despite any
code changes that may take place during the period of construction, until the permit expires if the
dwelling exterior is not completed within two years of permit issuance. The permit applicant
may submit a revision to the previously approved plans, if he or she desires to be covered by a
new code provision.
Repair work, as defined in s. Comm 20.07(61), also does not need to be done according to the
new code but rather may be done per the code at the time of original construction. Alterations
and additions per ss. Comm 20.07(2) and (4), to homes within the scope of the UDC, must be per
the current code. See s. Comm 20.07(61) of the code and this commentary for a discussion on
repairs and alterations to UDC homes.
20.02(5) Innovative Dwellings
The intent of this paragraph is to permit flexibility in the design and construction of houses. It is
not the intent of the code to permit unsafe construction or hazardous conditions to occur.
Therefore, when a house is designed outside the prescriptive or cookbook methods of this code,
the designer must demonstrate to the enforcing authority that the house will perform as required
by the code. Engineering performance standards are listed in ss. Comm 20.24, 21.02 and
elsewhere.
20.02(6) Landscaping
There will be very few conditions or circumstances under which the landscaping would impact
on the dwelling structure. One example would be in determining final grade where it may affect
the need for treated sills or rim joist per Comm 21.10. Another example might be a sidewalk,
landing, porch, or driveway not properly installed such that it is lifted through frost action to such
an extent that a door required as an exit cannot be opened. Further examples would include
window wells, used for emergency exits or light wells, also guardrails when there is elevation
changes of more than 24” and decks or landings and stairs of more than 24” elevation changes.
-2004-20-4-
20.04(3)
Also s. Comm 21.12 requires that the grade slope away from the dwelling to provide good
drainage. Landscaping may be part of an erosion control plan under Comm 21.125.
20.03 Effective Date
The effective date of chs. Comm 20, 21, 23, 24 and 25 was June 1, 1980. The effective date of
ch. Comm 22 was December 1, 1978. Additionally, there have been various revisions to all
chapters of the code since the original effective dates. Check the "History Notes" at the end of
each code section for effective dates of revisions. (See the Introduction page of the UDC for an
explanation of these history notes.) For purposes of determining what date a dwelling has begun
"construction," use the date of permit application. In the case of a manufactured dwelling, the
date that its construction started determines the applicable code edition.
20.04 Applications
Note that additions and alterations, as defined in ss. Comm 20.07(2) and (4), to dwellings that
were originally covered by the UDC are subject to the edition of the code at the time the permit
for the new work is applied for. Additions and alterations also require permit application as
required by local ordinance, but not new permit seals.
20.04(3) Bed and Breakfast Establishments
Section 254.61, Stats., defines a bed and breakfast such that it:
"(a) Provides 8 or fewer rooms for rent to no more than a total of 20 tourists or transients;
(b) Provides no meals other than breakfast and provides the breakfast only to renters of the
place;
(c) Is the owner's personal residence;
(d) Is occupied by the owner at the time of rental;
(e) Was originally built and occupied as a single-family residence, or, prior to use as a place of
lodging, was converted to use and occupied as a single-family residence; and
(f) Has had completed, before May 11, 1990, any structural additions to the dimensions of the
original structure, including by renovation, except that this limit does not apply to any of the
following:
1. A structural addition, including a renovation, made to a structure after May 11, 1990, within
the dimensions of the original structure.
2. A structural addition, made to a structure that was originally constructed at least 50 years
before an initial or renewal application for a permit under s. 254.64 (1) (b) is made and for which
no use other than as a bed and breakfast establishment is proposed. The structural addition under
this subdivision shall comply with the rules under s. 101.63 (1) and (1m)."
This section applies to both pre- and post-1980 built dwellings. However, it should be noted that
this same statutory section only allows structures completed prior to May 11, 1990, to be licensed
as a bed and breakfast establishment. It also states other eligibility standards. In any case, such
an establishment must be licensed by the State Division of Health and Family Services.(Tel. 608266-1120)
Bed and Breakfast esabilshments must comply with all of the provisions listed above - (a)
through (f). Those establishments that do not meet all of those provisions would need to comply
-2004-20-5-
20.04(6)
with the Commercial Building Code. Examples of non-conformance with the bed and breakfast
establishment provisions which would put the building into the category of Commercial Building
would be; a home built after May 11, 1990, serving more than just breakfast, serving breakfast to
other than the tenants or the owner does not occupy the residence at time of rental. As with the
bed and breakfast establishment, this Commercial establishment that rents out rooms to tourists
or transients and serves food would need to be licensed by the State Division of Health. Types of
licensing assigned to this Commercial building by the Division of Health might be bed and
breakfast establishment, tourist rooming house, hotel/motel or restaurant.
20.04(6) Multi-Family Dwellings and Commercial Occupancies
The Wisconsin Commercial Building Code, chs. Comm 60 through 66, are the rules that apply
to three- or more unit residential buildings as well as to commerical buildings that are places of
employment and publicly-accessed buildings built after October 9, 1914. (There is an
exemption for farming operations.) It also applies to dwelling or sleeping units that are in a
building with commercial use in which the total combined number of commercial and
residential tenant spaces is three or more. (The Buildings Constructed Prior to 1914 Code , chs.
Comm 75-79. applies to commercial buildings built prior to this date.)
The Commercial Building Code also applies to a situation in which three or more rowhouses are
connected together with construction, whether or not there is a property line, fire wall or both
separating the units. (See drawings in UDC Codebook Appendix for what are considered
separate dwellings.)
The following residential units are subject to the Commercial Building Code:
• Two or more apartments or rooming occupancy bedrooms in a building also used for
commercial purposes
• 1 or more apartments in a building also used by two or more commercial tenants
• 3 or more apartments or rooming occupancy bedrooms in a building
(A rooming occupancy is one in which bathing and cooking facilities may or may not be shared
but sleeping rooms are separately leased and secured from each other.)
The Uniform Dwelling Code does apply to a single dwelling unit or sleeping room constructed
after June 1, 1980, in combination with a single business tenant, while the applicable parts of
chs. Comm 60-66 apply to the business portion of the building. (In general, the UDC applies to
both non-transient and transient residential usages.) The residential portion would need to be
considered in the overall building area for Commercial Building Code compliance, unless it was
separated by a firewall.
Home-based businesses such as professional offices, beauty shops, car repair, etc., are generally
within the scope of the Commercial Building Code even if the business is located within the
dwelling proper. However, there are several exceptions:
• If there are no employes and the public does not enter for business purposes, OR
• If the activity meets the definition of home occupation of s. Comm 61.02(3)(h) & (4):
- maximum of 1 nonfamily employe,
-2004-20-6-
20.05(5)
- maximum 25 percent of the habitable floor area used,
- no explosives, fireworks or motor vehicle repair.
Note that per state statute s. 101.12(3)(h), municipalities are prohibited from issuing local
permits or licenses for construction or use of public buildings or places of employment until the
Department of Commerce has approved plans for such buildings, unless otherwise exempted
from plan review. For a summary of plan submittal requirements, request a copy of our
Commercial Plan Review brochure with the publications order form at the front of this
commentary.
20.05(3) Repairs
The intent of this section is to exempt repairs from plan submittal, permit application and
inspection requirements only. It does not exempt repairs from having to be preformed according
to the code that was in effect at the time of original construction. See s. Comm 20.07(61) of the
code and this commentary for a discussion of what constitutes a repair versus an alteration, the
latter would require permit application. Note that s. 20.02(1)(c) allows municipalities to have
more restrictive permitting requierments.
In order for a repair to occur, there needs to remain a dwelling, which means enclosed space
needs to remain. A complete collapse or totally burned out dwelling cannot be repaired.
Question:
Answer:
A home that was built in 1939 is relocated to a new lot and installed on a new
poured-in-place concrete foundation and basement. The home has interior doors
that are 2’-6” wide and the stairway to the basement is 2’-8”. Will the owner or
contractor have to correct both of these Code violations before occupancy of the
home can take place?
Unless the municipality has either an ordinance or a building code that was in effect
prior to 1980 and these items were violations of that code, at the time of
construction, the fact that the home is relocated and now placed on a new
foundation, the UDC still does not apply.
20.05(5) Accessory Buildings
An open breezeway with a roof attachment between a house and a garage would create one
building and cause the garage to be within the scope of the code even if it is located more than
10’-0” away from the dwelling and has open side-wall construction.
An outdoor pool is not subject to the UDC except for any electrical equipment located in the
dwelling. Also, the electrical code independently governs any outside wiring. The Plumbing
Code would also apply if there were any water or waste piping connecting the pool to the house.
20.05(5) Accessory Buildings - Decks
Question: Are decks considered accessory buildings?
Answer:
If the deck is not attached to the dwelling and not serving as an exit path from the
dwelling, then it shall be treated as an accessory structure, not covered by the UDC.
-2004-20-7-
20.05(7)
20.05(7) Farm Buildings
This code does not exclude a house located on a farm or a dwelling unit attached to an
agricultural building.
20.09(9) Motor Homes & Recreational Vehicles
This section exempts these types of vehicles from the UDC if they have been titled by the WI
Department of Transportation. In order for a recreational vehicle to be licensed it will need a
towbar or hitch, chassis, axles and wheels for transportation. At the parking site, the chassis and
axles shall remain on the unit, with towbar or hitch and wheels left at the site. Otherwise, the
unit, even if called a "park model" shall comply with the UDC as a dwelling. Regardless, any
on-site additions with a roof, to a motorhome or recreational vehicle are considered dwellings
that shall comply with the UDC.
Subchapter II  Jurisdiction
20.06 Procedure for Municipalities Exercising Jurisdiction
Subchapter II of ch. 20 sets out the procedure by which governmental jurisdiction is
accomplished. It is intended in both the law and code that state government has a minimum of
involvement when local governing bodies take on the Uniform Dwelling Code as a set of local
regulations. That is why local government is provided the authority to set fees, remedies, and
penalties and to carry out joint enforcement efforts with other municipalities.
The prime intent of state government involvement under these circumstances is to maintain
"uniformity" in the writing, adopting, interpreting, application and enforcement of the rules.
In the interest of uniformity on a statewide basis, the adoption of additional regulations relating
to a subject within the scope of the Uniform Dwelling Code is not permitted at the local
government level except through petitioning for a variance from the department.
20.06(1)(b) Enforcement Method
The fifth option for method of enforcement, contract with the Department, is generally not
available because of limited state staff. Only in situations where a municipality has failed to
provide for enforcement, will the state take over enforcement. Even in that situation, the state
will contract out the work to an inspection agency or certified inspector.
Municipalities still have a number of options to take to retain a certified inspector. These options
are available for both routine and nonroutine situations. This means that if the regular inspector
would have a conflict of interest or will be unavailable for a period of time in eccess of 48 hours
(two business days), then the municipality should arrange for another inspector, perhaps from an
adjoining municipality, to fill in while he is away.
Per this section, a municipality has broad discretion in the means of enforcing the UDC. Under
the joint enforcement option, a municipality may delegate enforcement of the UDC erosion
control requirements, including legal prosecutorial follow-up, to a county that has adopted the
-2004-20-8-
20.06(4)
UDC by ordinance. Alternatively, the municipality may contract with the county to provide plan
review and inspection services but retain legal prosecutorial follow-up.
20.06(1)(c) Submission of Ordinances
A local ordinance adopting the UDC for enforcement should include the following elements:
1.
The ordinance which names the Uniform Dwelling Code as the construction regulation for
the municipality;
2.
The ordinance which establishes the office of building inspection or which sets forth the
authority and duties for inspections to be made;
3.
The ordinance granting authority to establish fees, with or without the actual fee values;
and
4.
The ordinance which spells out what steps must be followed to accomplish compliance
and what fines or forfeitures will be assessed for failure of compliance.
Sample model ordinances are available from the state UDC Program in the Safety and Buildings
Division. (A copy is included in the appendix of the UDC Codebook.)
20.06(1)(c) Passage of Ordinances
Question: Once a municipality has adopted the code and have begun inspections, does it have
the option of stopping it any time?
Answer:
A municipality may withdraw from local enforcement of the code. Subsection
Comm 20.06(1)(a) requires that prior to local adoption and enforcement of the UDC
in a municipality, the department must be notified at least 30 days prior to the date
of which the municipality intends to exercise jurisdiction. Repeal of a municipal
ordinance for the purpose of withdrawing from participation in the program, should
be accompanied by notification to the department that such a withdrawal will take
place and what other methods of enforcement will be used in that community. If the
ordinance is not repealed and not enforced, the town may be exposing itself to some
liability.
20.06(3) County Jurisdiction
This option offers potential advantages of a centralized building, zoning and sanitary permit
issuing office. It was also expected to be a more uniform and efficient enforcement method than
each individual town, village or city hiring its own inspector. Counties have the option of
enforcing the UDC wherever a municipality of over 2500 population does not have a UDC
enforcement program. In addition, the Department of Commerce will typically delegate UDC
enforcement in non-enforcing municipalities of 2500 or less population to a county that has a
UDC program.
20.06(4) Departmental Jurisdiction
-2004-20-9-
20.065(1)
The department currently only seeks contracts with independent inspection agencies for UDC
enforcement in those municipalities which fail to adopt an ordinance, unless the municipality is
covered by an enforcing county.
20.065(1) State Jurisdiction
Per this the state statute referenced in this section, the Department may monitor municipalities
for compliance with the UDC provisions and for general performance.
Subchapter III  Definitions
20.07(5m) Attached Structures
Two structures are attached if they share a roof, floor or foundation. However, it was not the
intent of this section to consider a slab-on-grade or deck-on-sleepers as being either a shared
floor or foundation between two structures.
Solid Roof
Covering over
Walkway
Dwelling
Garage
Garage and walkway
part of the dwelling
and within the scope
of UDC
20.07(27) Dwelling Unit
Question: What constitutes separate dwelling units within the same dwelling?
Answer:
The key phrase in the definition is “. . . common household, to the exclusion of all
others." So if two living areas have separate exiting and no common use areas, then
they are separate dwelling units.
-2004-20-10-
20.07(27)
FIRST
FIRST
BASEMENT
GROUND
FLOOR
GRADE
FIRST
GRADE
SECOND
FIRST
BASEMENT
SECOND
FIRST
**
FIRST*
GROUND
FLOOR
BASEMENT
FIRST
FIRST
BASEMENT
FIRST*
BASEMENT
FIRST
FIRST
**
**
FIRST
GROUND FLOOR
GROUND
FLOOR
BASEMENT
*There is always a first floor in a dwelling
**See s. Comm 21.03(11)
s. Comm 20.07 (8), (34k), 36m)
BASEMENT, FIRST FLOOR AND GROUND FLOOR DEFINITIONS
-2004-20-11-
**
20.07(37)
20.07(37) Unfinished Habitable Rooms
Question: What constitutes a habitable room in terms of completion? Oftentimes a plan
shows a "future" room, but at the time of final inspection, such a room appears to be
used as a recreation room without being completed. When should all habitable
room features, such as ceiling height, natural light, ventilation, electrical outlets,
wall and ceiling finishes, be required?
Answer:
If a room is intended to be habitable at the time of occupancy, then the required
"habitable room features" must be present. However, inspectors usually finish
inspecting prior to occupancy, and give conditional occupancy. These unfinished
rooms may be allowed as long as they are not inhabited when the owner wishes to
occupy the rest of the dwelling. The owner shall call for a follow-up inspection to
release any occupancy conditions. However, in no case should partially completed
rooms pose an increased health or safety hazard such as in the case of exposed
wiring. See the discussion regarding final inspections under s. 20.10(1)(b)3. of this
commentary.
20.07(50) Loft
It is important that a loft be open to the floor below so that there is good sound
communication, clear sight lines and adequate air (and odor) movement between levels as
well as the possibility of jumping down between levels. These factors are important so
that occupants are quickly alerted to any problems elsewhere in the dwelling. This early
alert offsets the relaxed exiting requirement in s. Comm 21.03(4). This section requires
only one stairway or ladder and no egress windows, no matter what level above grade that
the loft is. Note that the definition requires all habitable rooms to be open to the floor
below. See diagrams.
20.07(53f) Modular Home
This is the new term for what was previously referred to as a manufactured dwelling in the UDC
and are produced in factories to the requirements of the UDC. They are different than
manufactured homes that are produced in factories to the federal HUD standards.
-2004-20-12-
20.07(53f)
DESIGNS
“A”
“C”
“B”
SECTION
Bath
Bedroom
PLAN
OK
Area of opening is at least 50% of
common wall. (Open guardrail
OK.) Bath is not habitable room so
can be closed off.
NO
Common wall is not at least 50%
open.
LOFT AREA
NO
Rear bedroom (habitable room) is
not open to floor below.
CONTINUOUS PARTITION
s. Comm 20.07(50) LOFT - ACCEPTABLE DESIGNS PER DEFINITION
-2004-20-13-
20.07(61)
20.07(61) Repairs
The determination of what constitutes a repair is often best made by the local building inspector.
Many municipalities have guidelines to distinguish between repair and alteration. Some consider
square footage, cost of construction, or whether it affects exiting or structural features. The
following discussion should be considered supplemental to local guidelines.
A repair normally involves work to maintain an existing system or feature of the building
without changing it from its original condition at the time of original construction. In order for a
repair to occur, there needs to remain a dwelling, which means enclosed space needs to remain.
A complete collapse or totally burned out dwelling cannot be repaired. An alteration normally
involves a change or modification of an existing system or feature to the extent that is now
subject to different code regulations.
Examples:
1.
The rebuilding of a rotted out sliding patio door to a swinging type door when that
opening is required as an exit will be an alteration and not repair or maintenance. The
door width, exit operation (swing) and header size may be altered and deserves code
review under the current code.
2.
The replacement of a toggle type light switch to a dimmer type light switch would be
considered repair or maintenance. No change in function.
3.
Replacement of siding could be considered an alteration if its intent was to affect
compliance with the energy conservation rules. However, new siding placed over the
top of old siding would be considered maintenance or repair not coming within the
scope of the code.
Subchapter IV  Approval and Inspection of One- and 2-Family Dwellings
20.08 Overview
An overview of the approval and enforcement process:
1. Owner or agent submits a Uniform Building Permit Application and complete building plans
to the municipality or third party agency administering and enforcing the code.
2. The certified inspector approves or disapproves the plans based upon a review of the
submittal documents, prior to permit issuance.
3. If the plans are approved then the applicant is issued a Uniform Building Permit. If this is the
original construction of the dwelling, the building permit shall have a Building Permit Seal
attached or number entered.
-2004-20-14-
20.09(1)
4. The Wisconsin Uniform Building Permit shall be posted at the construction site. Inspections
shall be recorded by the inspector when they are performed.
5. The administering and enforcing agency shall inspect the building in various required stages
of completion. A record of these inspections shall be kept by the enforcing agency.
6. When the final inspection report is issued without any health or safety violations, the home
may be occupied.
Forms and seals needed for administering and enforcing the code can be obtained by
municipalities from the state Document Sales office, using the order form at the front of this
commentary.
Records generated by the plan review and inspection functions are subject to the open-records
law. It is also advisable that inspectors maintain logs of permits issued and inspections made.
20.09(1) Wisconsin Uniform Building Permit (See UDC Codebook Appendix for sample forms.)
A Wisconsin Uniform Building Permit card (Form SBD-5824) must be issued prior to any
construction of, including excavation, one- and two-family dwellings that are not exempted by s.
Comm 20.05. Note that repairs as defined in s. Comm 20.07(61), do not require a permit,
although continued compliance with the Code at time of original construction is required. Per s.
Comm 20.04(1), additions and alterations may require a permit per local ordinance and are
subject to current code. See s. Comm 20.07(61) of the code and this commentary for the
definition and discussion of "repairs."
Failure to obtain a permit prior to construction may result in fines and increased permit fees as
required by local ordinance. Also, any concealed work may need to be uncovered to allow
inspection.
Municipalities may issue one building permit to cover all categories of construction or the
municipalities have the option of issuing building permits to individually cover each category of
construction (construction, heating/ventilating/air conditioning, electrical and plumbing). A
separate building permit should not be issued for energy since the energy conservation measures
are integral with the four major construction categories. Builders also have the option of
applying for separate permits.
Regardless whether separate heating, plumbing or electrical permits are used, only one permit
seal per dwelling should ever be issued and it should accompany the initial "construction"
building permit.
The Wisconsin Uniform Building Permit Application may be used locally for all project types.
However, UDC seals would only be issued on new one- and two-family projects. Also, a
municipality may request additional information on their form.
-2004-20-15-
20.09(2)
20.09(2) Filing of the Wisconsin Uniform Building Permit Application
Where a municipality or county does not enforce the code, an applicant must file the application
with the inspection agency contracted by Department of Commerce for enforcement services.
On a montly basis, municipalities and inspection agencies shall submit a copy of the Uniform
Building Permit Applications issued for new homes where a seal is required (see below) to the
department. Data from these permit applications is tabulated by the department and published on
our website.
The department strongly encourages municipalities to adopt a one-stop permit program for UDC
requirements, as well as non-UDC requirements, so as to minimize the regulatory burden on
permit applicants.
20.09(3) Fees
Municipalities administering and enforcing the code may establish fees to cover expenses. State
statute 66.0628 limits municipal fees to the cost of the services provided. The fees charged
should allow for administration cost, plan review, inspections and Building Permit Seal. There is
additional information on our website regarding the establishment of fee schedules.
A Department of Commerce Building Permit Seal must be assigned to each new dwelling by the
municipality or state-contracted inspection agency. They shall be purchased by the municipality
or inspection agency from State Document Sales (see order form at the front of this
commentary).. A Building Permit Seal is only required with the initial construction permit
(either full permit or footing & foundation approval) for a dwelling. Seals must be issued for
both site-built and factory-built homes, including manufactured homes manufactured after April
1, 2007 and modular homes. Subsequent permits for additions and alterations do not require a
seal. Seals are assigned to a single living unit contained in a commercial building or to the
conversion of a nonresidential building to a new dwelling.
Following is an example seal. (Seal Color is Orange)
20.09(5) Required Building Plans
The agency approving the plans has the right to request additional information to clarify
drawings and data necessary to ensure that the building shall comply with the Uniform Dwelling
Code when built. It should be remembered that it is much easier to correct a design on paper
than when it is built.
-2004-20-16-
20.09(5)
Although modular and manufactured homes will have their plans approved by other agencies, the
plans for any on-site construction are submitted to the enforcing municipality along with the
Building Permit Application. A UDC Seal is assigned to the on-site work just as for any new
dwelling.
Following is a checklist for plan submittals. Also following is a cross-sectional drawing showing
major code items.
The use of each room shall be shown to allow proper review for light, ventilation, exiting and
other requirements.
20.09(5)(c) Architect- or Engineer-Stamped Plans
This section details the procedures for obtaining a Uniform Building Permit, including plan
submission requirements. This section allows municipalities to require engineered plans and
calculations but prohibits a municipality or the department to require such plans or calculations
to be prepared or stamped by a registered architect, engineer or designer. However, the
inspector should require that the plans or calculations clearly indicate they were prepared for the
dwelling in question. The inspector should also require that preparers identify themselves and
date the plans and/or calculations. An exception to this prohibition is s. Comm 21.33 and 21.34
regarding construction in floodplains.
If the inspector does not feel qualified to review innovative or structurally complex designs, the
inspector can forward the plans and calculations to the Department of Commerce for review and
approval. The inspector should specify what issues that they are requesting state review. The
department will charge a fee for such a review per s. Comm 2. Since the Department of
Commerce would perform this service for the municipality, the municipality would be billed for
the review. The balance of the review, permit issuance and all inspections would remain the
responsibility of the municipality.
20.09(5) Building Permit Checklist
This is a checklist for submitting drawings and information when making application for a
Wisconsin Uniform Building Permit. Apply those portions where the dwelling has on-site
construction. Do not apply to the factory-built portion that has been approved by another agency.
Drawings must be legible and drawn to scale or dimensioned and include:
1. A plot plan showing the location of the dwelling and any other buildings, erosion
control and stormwater measures, wells and disposal systems on the property and
property lines. For rural areas, include directions for locating dwelling. See UDC
Appendix……
2. Floor plan which shows:
The size and locations of:
1)
Rooms
2)
Doors
3)
Windows
4)
Room use
-2004-20-17-
20.09(5)
5)
3.
4.
5.
6.
Structural features - size, species and grade of lumber or other
structural material for braced wall lines, joists, beams, rafters, trusses,
headers, studs, and columns; strength, thickness, and reinforcement (if
any) of concrete for footings, foundations, floors and any other
concrete work; height and thickness of concrete and/or masonry
construction
6)
Exit passageways (hallways) and stairs (including all stair dimensions riser height, tread width, stair width, headroom and handrail heights)
7)
Plumbing fixtures (bathroom, kitchen, etc.) - lavatory, water closet,
water heater, softener, etc.
8)
Chimney(s) - include also the type of construction (masonry or factory
built) and rating, if metal
9)
Heating equipment and the location of supply and return registers
10)
Cooling equipment (central air conditioning, if provided)
11)
Attic and crawl space access
12)
Fire separation between dwelling and garage
13)
Lateral bracing
Elevation drawings which show:
A.
Information on exterior appearance
B.
Indicate the location, size and configuration of doors, windows, roof,
chimneys and exterior grade level
Cross-sectional drawing which shows (see following generic drawing):
A.
Exterior grade level
B.
Footing and foundation wall sizes, drain tile system and types of materials
C.
Exterior wall construction identifying materials used (including insulation
and vapor barrier)
D.
Roof construction identifying materials used and spans (including insulation
and vapor barrier)
E.
Floor construction identifying materials used and spans (including insulation,
if used)
Any additional information to help determine compliance with the code, such as:
(Optional at inspector's request.)
A.
Location of electrical outlets, lights, switches, main distribution panel and
smoke detectors
B.
Manufacturer's name, model number, and input/output rating of heating
appliance(s). Also include cooling appliance if central air is installed
C.
Size and location of ventilation openings for attics and crawlspaces (can be
shown on floor plans or elevation plans)
D.
Location of any exhaust fans to be installed
E.
Plumbing isometric plan
Either a completed RESCheck or RemRate energy report or a photocopy of of Table
22.31-1 or 22.31-4 with the proposed R-values circled. If the latter option is chosen,
then a separate heat loss calculation for heating plant sizing is required.
-2004-20-18-
20.09(5)
NOTE:
OWNER: ___________________
PROJ. LOC: _________________
DATE: _____________________
DESIGNER: _________________
With proper detailing of building dimensions, material types, spans, sizes, spacing,
Fh, properties, etc., and strikeouts of non-applicable details, this cross section
would provide an acceptable plan drawing. With the local inspection authority’s
permission, this drawing may be detailed by a designer and submitted as part of a plan
package for plan review. (Fb - Fiber bending stress of selected lumber.
Alternatively, grade and species information may be noted.)
- RIDGE BOARD
VENTING:
ROOF SLOPE:
ROOFING:
UNDERLAYMENT:
DECKING:
RAFTERS/TRUSSES:
AIR CHUTES:
ROOF ANCHORAGE:
EAVE PROT.__________________
-COLLAR TIES
-INSULATION
-JOISTS
-VAPOR BARRIER CEILING FINISH
-
VENTING:
EXT. COVERING:
EXT. SHEATHING:
WATER-RESIS.BARRIER _____________
MAS. VENEER:
AIR SPACE:
BRICK ANCHORAGE:
FELT/FLASHING:
FOUNDATION ANCH.
SILL PLATE:
TOP COURSE:
WEEPHOLES _____________________
GRADE:
FDTN. INSUL:
INSUL. PROT:
FDTN. TYPE:
FDTN. THICKNESS :
REINFORCEMENT:
DAMPPROOFING:
BACKFILL:
- WALL FRAMING
- INSULATION
- VAPOR BARRIER
- INT. WALL FINISH
CEILING HT:
- FINISH FLOOR
- FLOOR DECK
- JOISTS
- BEAM
FDTN. HT:
-COLUMN
- FLOOR
- VAPOR RETARDER
- BASE COURSE
- FOOTING
TILES & BLEEDERS:
FOOTING:
-2004-20-19-
20.09(6)
20.09(6) Approval of Plans and Issuance of Permits
UDC building plans must be reviewed and approved by a Department of Commercecertified inspector.
"Substantial conformance" of the plans to the code is a determination to be made by the
plan examiner. If the noncode-complying items found can be corrected without major
structural or design revision, the plans may be stamped "Conditionally Approved." Any
noted conditions that must be met in order for the building to comply must be indicated in
writing on either the Permit Application or by letter to the permit applicant.
Should the plan examiner (or inspector) should miss any items that do not comply with
the code at the time of permit issuance, the owner must still correct the omitted item if the
noncompliance is discovered at a later date.
The Wisconsin Uniform Building Permit card is issued only after the plans have been
approved. The information contained on the building permit card is obtained from the
application. The Wisconsin Building Permit Seal is affixed or its number recorded on the
permit card at this time. The number is also recorded or affixed on the application form.
Only one permit seal is ever assigned for a dwelling despite any subsequent additions or
alterations. A permit seal is issued regardless if it is a site-built or premanufactured
dwelling.
20.09(9)(a) Summary of State Contractor Credentialing
The following types of activities require credentialing by the State Division of Safety and
Buildings:
• Contractors taking out construction or energy conservation permits for one and
two family dwellings, regardless of its age, shall possess the Dwelling Contractor
certification and have on staff an individual with the Dwelling Contractor
Qualifier certification.
• Plumbers
• Automatic fire sprinkler fitters and contractors
• Certified soil testers for private sewage systems
• Structural welders for commercial buildings
• Refrigeration and air conditioning technicians
• Installers and removers of underground and flammable liquid storage tanks.
• HVAC & refrigerant contractors.
• Elevator contractors and installers
• Starting July 1, 2009, building contractors that do not otherwise have a business
credential issued by the Department of Commerce, will need to obtain a Building
Contractor Registration if they perform code-related work on dwellings or
commercial buildings.
In addition, the Division offers voluntary master and journeyman electrician
certifications, in lieu of any municipally-required examination, and a voluntary electrical
-2004-20-20-
20.09(9)(a)5.
contractor certification. This is scheduled to be mandatory in 2013. For either the master
or contractor certification, municipal license fees may still be charged. Contact us at
(608)261-8500 for further information on any of these programs.
Other state agencies also have licensing programs for trades allied with construction.
• The state Division of Health (608-266-9382) certifies roofing and siding
contractors working with asbestos containing materials, as well as for other
asbestos related activities. They also certify contractors dealing with lead-based
paint removal.
• The Department of Natural Resources (608-266-0162) licenses well drillers and
pump installers.
• The Department of Regulation and Licensing (608-266-1397) licenses architects
and engineers, which are required to design foundations in floodplains per s.
Comm 21.33 and 21.34.
• The Department of Regulation and Licensing (608-266-5511) licenses “Home
Inspectors" involved in the sales of existing homes (secondary market homes)
which may or maynot have been built to the UDC requirements call for further
information.
All businesses are obligated to comply with any applicable Worker Compensation
requirements (608-266-1340), Unemployment Compensation requirements (608-2663114), sales, use or withholding taxes (608-266-2776) and corporate registration
requirements (608-266-9869).
Question:
Answer:
Does a municipality have the authority to license trades other than plumbers
and HVAC contractors working on a home under the UDC?
Wisconsin statute s. 101.63(2) generally allows municipalities to require
licensing of the trades, including an owner-occupant.
20.09(c) Sanitary Permits
A concern here is the determination of whether an existing septic system "satisfies all
applicable requirements" of the codes. Typically, the county sanitary inspector would be
the person to contact for such a determination. The system's capacity, operating condition
and the maintenance of the required setbacks are considered by the county inspector.
Related to this question is the need to get proper zoning or floodplain authorization for a
dwelling. This would typically come from the local municipality and sometimes the
county, especially in smaller municipalities. Also, some counties require well permits to
be obtained prior to drilling. See the UDC Codebook Appendix for additional
information.
20.09(9)(a)5. Expiration of Permit
Question: The code requires that a permit shall expire 24 months after issuance if the
exterior is not completed. What happens in the case where the dwelling
-2004-20-21-
20.09(9)(b)
Answer:
exterior has been completed within 24 months but construction may
continue for several years or more before the building interior is completed?
The 24-month period before the permit expires was set up so that there was
a time limit on how long a permit was valid for building a dwelling's shell.
Otherwise, s. Comm 20.04 merely requires that a completed or uncompleted
dwelling conform to the code in effect at the time the permit is issued. In
the case of an uncompleted dwelling with a completed shell, the interior may
continue to be completed under the code in effect at permit date. If
alterations to the original plan approval occur, revised plans shall be
submitted and reviewed under the current code. Occupancy may not be
allowed if health or safety violations exist per s. Comm 20.10(1)(b)4a. & b..
Inspectors or other local officials may be able to invoke the raze and remove
orders of s. 66.0413, Wis. Stats., in cases where a dwelling is a public
hazard because construction has started and then ceased for more than two
years.
Also, municipalities may require additional fees to extend the original time
period of a permit.
20.09(9)(b) Permit to Start Construction of Footings and Foundation
If an application wishes to start construction of only the footings and foundations of a
dwelling before the plans have been reviewed and approved, a Permit to Start
Construction (Form SBDB-6072) may be issued. This permit allows construction to
begin on the footing and foundation and erosion controls only. The applicant agrees to
make any changes that may be required as a condition of plan approval while maintaining
erosion control measures.
Subsequent non-foundation work may not proceed until the building permit is issued.
20.09(10) Action to Approve or Deny
The plan examiner must notify the applicant in writing within ten business days that the
plans have been:
1.
Conditionally approved
2.
Approval withheld pending receipt of additional information. In this case,
the code required time period to take action to approve or deny begins anew.
3.
Not approved.
4.
Sent to Department of Commerce for review.
If plan approval is being withheld pending additional information, the applicant must be
informed in writing what the additional information is required.
20.10 Inspections – Inspector Certification
State statute 101.66 and the Uniform Dwelling Code s. Comm 20.10, require that any
inspections made for the purpose of administering and enforcing the Uniform Dwelling
-2004-20-22-
20.10
Code shall be performed by persons certified by the Department of Commerce. If a
builder or designer suspects that an inspector(s) is not properly certified in one or more
UDC categories of construction, HVAC, electrical or plumbing, you may request to see
their certification card. The State UDC Program will also investigate such cases upon
written complaint.
It should be remembered that municipalities can jointly exercise jurisdiction through the
use of an independent inspection agency or by coordinating their inspectors. For
example, Municipality "A" may contract with Municipality "B" for electrical inspections;
and Municipality "B" may contract with Municipality "A" for heating inspections.
Municipality "A" and "B" may also have arrangements for inspectors to cover for each
other when on leave. This flexibility also makes it easier for municipalities to administer
and enforce the code by allowing them to utilize many inspectors rather than only one
inspector certified in every category.
By state Attorney General's opinion, the Department of Commerce is not liable for
actions by inspectors it certifies.
Question:
Does a local building inspector have the authority to enter a house, without
permission, where there is no building permit issued?
Answer:
This might be better addressed by a municipality's legal staff. However the
Wisconsin Statutes in ss. 66.122 and 66.123 describe a building inspector as
a "peace officer" and explains the purpose for which he or she may make
inspections and the procedure to be used if refused entry. When a state
inspector is denied entry to a building to perform his or her duties, we
request the local circuit court to issue an inspection warrant for us to
continue with our duties.
20.10 On-Site Inspections of Modular and Manufactured Homes
The inspections shall follow the same procedure as the stick-built home. There shall be
an inspection of the excavation, footing, foundation, below and above grade foundation
insulation, and a final inspection. All of the rough inspections on the home itself will be
made by certified inspectors in the plant. The municipality or agency performing on-site
inspections will be responsible for inspecting the electrical, plumbing, structural and
insulation systems installed at the site.
Although in-plant work may be done by nonlicensed workers, any on-site work must be
done by properly licensed workers and contractors.
20.10 Inspections - General
Iinspections are to ascertain whether the structure conforms to each of the following:
1.
The approved plans;
2.
The conditions of approval of the Uniform Building Permit; and
3.
The provisions of the code.
-2004-20-23-
20.10(2)(b)3.
Note that the inspector may inspect for compliance with the approved plans that showed
items that were above and beyond the minimum code requirements. If it is no longer
desired to build the dwelling as originally designed and approved, the applicant may need
to submit revised plans to the inspector for review and approval.
Occasionally, an inspector will discover a noncompliance that was missed on a prior
inspection or plan review. The inspector clearly has authority to order correction. The
use of checklists will help to minimize this.
In order to start the formal enforcement process, corrections must be ordered in writing
with copies to the owner and permit applicant. The municipality may use its own
inspection forms or Department of Commerce Inspection Report and Notice of
Noncompliance Form, (SBD-6025).
20.10(2)(b)3. Inspection Notice
Several clarifications on this issue:
• This provision requires that the contractor wait at least two full business days after
the day of inspection request before covering up the work if an inspection has not
been performed.
• The work shall be ready for inspection when the request for inspection is made, or
the request should indicate when the work will be ready and then the two-day
period would begin then.
• The two business days notice of the UDC supercedes the 24-hour notice
requirement of the Plumbing Code in s. Comm 82.21.
Question:
Answer:
Are there guidelines for inspectors that require them to be available during
normal working hours?
There are no specific guidelines regarding such availability.
Section Comm 20.10 details the type of inspections required and notification
of inspection responsibilities. It also requires the inspections to be
conducted within two normal business days of notification. Nothing would
require the inspector to be available at certain times of the day. From a
practical standpoint, a municipality should develop a procedure to clarify
how the builder may contact the inspector. It may also be a good idea for
the inspector to formalize his or her hours of availability. There are some
valid concerns about non-business hour inspections including adequate
daylight conditions, inspector access to the site, and contractor availability if
question should arise. Such concerns may be best addressed to the inspector
or to his or her superior.
20.10(3) Inspection Types
Depending on the number of inspectors involved, coordination of the trades and the type
of construction, the number of separate inspections could vary from four to eleven. There
may be additional inspections necessary due to callbacks regarding incomplete work or
-2004-20-24-
20.10(3)(f)
noncomplying conditions.
Prior to performing any inspections, it would be a good policy for the inspector to review
the approved plans. Particular notice should be given to any deviations or unusual
conditions that may exist.
20.10(3)(c)&(d) Footing and Foundation Inspections
Some points regarding footing and foundation inspections:
• If there are no required drain tiles, no required reinforcement or no forms, i.e.
"dug footings", then an inspection can be made of the dwelling excavation in
advance of the footing work to check for proper soil conditions. The next
inspection can be made after the placement of footing and foundation
materials and prior to backfill to verify footing dimensions.
• If there are required drain tiles, the code requires that the bleeders be inspected
prior to pouring the footing.
• Reinforcement for basement window headers, reinforced masonry walls and
foundation stepdowns do require inspection prior to pouring of concrete or
laying of subsequent masonry courses. Note that some short-span foundation
step-downs, where the foundation is unsupported by the earth for only several
feet may not require reinforcement based on arching action.
• Reinforcement for masonry walls does need verification prior to grouting of
the cores.
• Wood Foundations - Inspected after framing and exterior sheathing and prior
to the placement of gravel.
Depending on construction, it is possible that the footings and foundation could be
inspected along with the rough inspections discussed below.
20.10(3)(f) Rough Inspections
The important principle to remember is that all work must be inspected prior to
concealment. It is possible that all of the construction trades are coordinated enough so
that all the rough-in inspections can be accomplished during one inspection. However, it
is unlikely that the insulation inspection can be done at the same time because the
insulation normally conceals the other work. Also, the rough framing inspection is best
done after the electrical and heating work is done so that notching and boring can be
checked.
Occasionally, a contractor will not properly call for an inspection so that the inspector
does not have the opportunity to verify compliance prior to concealment of some work.
Possible options that the municipality may consider are:
•
•
•
•
removal of all covering work so a full inspection can be made,
removal of representative section(s) of covering work as chosen by the
inspector,
alternative testing of materials,
affidavits by witnesses verifying the original work, or
-2004-20-25-
20.10(3)(f)1.c.
•
noting on the permanent file, and possibly on the property deed, that
compliance of certain items was not verified.
Selection of the option(s) is at the discretion of the municipality and should be done in
consultation with the municipal legal counsel.
20.10(3)(f)1.c. Rough Electrical
Section 101.865 of the Wisconsin Statutes requires that the utility furnishing the electrical
current obtain proof that the wiring complies with these standards before furnishing the
current. Proof must be a certificate furnished by the inspection department which may be
the certified independent inspection agency or the municipality administering and
enforcing this code. The electrical utilities will require a certificate of inspection prior to
energizing the electrical services, be they temporary or permanent installations. If there is
no certified agency or municipality, proof consists of an affidavit furnished by the
contractor or other person doing the wiring.
20.10(3)(f)1.d. Rough Plumbing Inspections
There may be separate required inspections for the sewer and water laterals, underslab
plumbing and the rest of the rough plumbing.
20.10(3)(g) Insulation
Generally, the insulation and vapor barrier are installed after all other rough inspections
have been made so as to avoid displacement of the insulation by the heating, electrical or
plumbing systems. Note that s. Comm 21.25(2) requires that the wall's water-resistive
barrier and roof's underlayment be installed prior to insulation of the exterior walls.
20.10(3)(h) Final Inspection-Inspector Certification
A final inspection prior to occupancy requires inspections of the construction, HVAC,
electrical and plumbing systems by an inspector or inspectors certified in all of those
categories.
20.10(3)(h) Final Inspection - Health and Safety Items
Special attention should be given the words "health and safety" in this section. It is
clearly not the intent of the Uniform Dwelling Code to prevent persons from moving into
their homes where certain cosmetic items have not been completed. For example,
unpainted rooms, uncompleted trim work, lack of carpeting, etc., would not prevent
occupancy.
On the other hand, incomplete exiting arrangements, open electrical boxes, missing
handrails and guardrails, open plumbing drains, etc., could constitute items affecting
health and safety and would prevent occupancy.
Generally, we would discourage occupancy prior to installation of wall or ceiling board,
i.e., drywall, rocklath, paneling, or other materials, that would protect the electrical
wiring, plumbing and insulation systems. No wires or equipment shall be exposed so as
-2004-20-26-
20.10(3)(h)
to create a hazard to the safety of the occupant. All electrical receptacle outlets and
lighting outlets shall have the receptacles with faceplates and fixtures installed. In the
case of NM electrical cable, it must be covered or closely follow the surface of building
finish.
Basic plumbing requirements for personal hygiene and culinary purposes that must be
installed in the dwelling are a stool, wash basin, tub or shower, kitchen sink and hot
water. All must be fastened in place and must be functional. This means water service
and drain, waste and vent piping must be provided and operational. The wash basin,
kitchen sink, tub or shower must have hot water connections and all unused sewer
connections must be sealed.
Occupancy may take place after the fifth full business day after the day of request for a
final inspection is made and no inspection is made, assuming that the dwelling is ready
for inspection at that time. Otherwise the clock starts at the time when the dwelling is
ready.
Note that this ability to occupy does not address the need to satisfy any additional zoning
or utility requirements prior to legal occupancy.
20.10(3)(h) Basement, Underground and Earth-Sheltered Dwellings
This section allows occupancy of a basement prior to the completion of the full dwelling
if it would otherwise comply with the code. It also refers to any provisions dealing with
underground dwellings. However, the code is silent regarding special provisions for
underground dwellings other than the need to design for soil loads. Therefore, the
following relevant general code provisions apply to basements as underground or earthsheltered dwellings:
•
s. 20.07(34K) Definition of first floor requires that there always be a first
floor. Therefore, unless there is a substantially complete upstairs, the
basement must be treated as the first floor.
•
s. 21.03(1) Requires two exits from the first floor. Bedroom egress windows
may qualify in a small dwelling.
•
s. 21.05(1) Requires natural light to all habitable rooms. The exception in s.
21.05(1)(a) for habitable rooms, other than bedrooms, in basements and
groundfloors does not apply here since this is now considered the first floor.
Skylights may be used to meet this requirement as may the exception in s.
21.05(1)(b) that allows borrowing of light between rooms.
•
s. 21.05(2) Requires natural or mechanical ventilation for most rooms. Again
openable skylights would be acceptable.
-2004-20-27-
20.10(3)(h)
•
s. 22.06/22.12 Requires compliance with envelope insulation requirements.
The ceiling must be insulated per these sections and protected with a vapor
barrier.
This is not a complete listing of applicable code requirements - just those in the UDC
needing highlighting. The Electrical and Plumbing Codes must be complied with,
including proper outlet placement and fixture venting. Also, the final inspection, per s.
20.10(1)(b)3., requires all health and safety items to be completed.
The intent of this code application to basement dwellings is to ensure that the basement
will safely perform as a dwelling until, and if, the rest of the dwelling is completed.
20.10(3)(h) Occupancy Permit
Question:
Under the UDC is an "occupancy permit" required?
Answer:
The UDC does not describe or require an "occupancy permit" procedure.
The "occupancy permit" is a procedure used by municipalities. Wisconsin
Statutes recognizes this in s. 62.23(9) and such a procedure would be in the
local Building Inspection Department's ordinances.
20.10(4) Notice of Compliance or Noncompliance
It is important to note that the enforcing authority must notify the applicant and owner
in writing of any noncompliances in order to begin a legal enforcement action or to
prevent occupancy. Oral orders or notes posted at the jobsite would have limited, if any,
legal significance. The municipality enforcing this code may in fact wish to notify the
applicant or owner by Registered Mail of violations.
Thirty days after notice without correction, the inspector should write a citation if they
have that authority or refer uncorrected orders to the municipal legal counsel, who may
initiate legal action as in s. Comm 20.22, Penalties & Violations, if corrections have not
been made. Each day after the 30 days shall constitute a separate violation per s. 101.66
of the Wisconsin Statutes.
Form SBD-6025 "Inspection Report and Notice of Noncompliance" should be used to
issue written notice unless the municipality has developed an alternate form. (See UDC
Codebook Appendix.) Note that a specific code section shall always be cited.
Municipalities may charge additional inspection fees as necessary to determine if
noncompliances have been corrected.
This section also requires notice that no noncompliances were found so that contractors
will clearly know that they can proceed. This may be written on the permit card or other
visible location at the jobsite.
Municipal legal counsels have broad latitude in judging whether to pursue legal action
-2004-20-28-
20.11
against a noncomplying builder or owner. But this is the counsel's decision, not the
inspector's, to make. The inspector should write the orders as he or she sees them.
20.10(5) Voluntary Inspection
Because the state inspection staff has limited available time, the Department of
Commerce normally refers homeowners and builders to independent inspectors when
they are seeking a voluntary inspection of their house They may be seeking inspection
services because of lender requirements or to satisfy their own quality assurance
concerns.
An inspector in this situation does not have municipal or state enforcement authority.
Rather, he or she is providing a report which the owner or lender can use to pursue
compliance and/or private litigation if necessary. Also, per state statute 101.02(11), an
owner may withhold payment to a contractor that fails to comply with the UDC.
20.11 Suspension or Revocation of Wisconsin Uniform Building Permit
Question:
Can a local building inspector issue a "stop work" order under the UDC?
Answer:
The UDC does describe a "stop work" order in Comm 20.10(1)(c). The
enactment of 1991 Wisconsin Act 309 now gives stop work authority to the
department, city, village, town or county for violations of erosion control
requirements. This authority (State Statutes ss. 101.653 (7)(b)) is only for
erosion and not extended to other UDC requirements.
When the UDC is adopted by a municipality, it may use its ordinances for
administrative procedures. Under state statute ss. 62.11(5) and 62.17,
municipalities have broad powers to enforce ordinances. We are aware of
many municipalities using "stop work" orders, also known as "red tagging"
procedures.
Subchapter V  Approval and Inspection of Modular Homes and Their Components
Overview
Most of this subchapter sets the procedures for manufacturers of modular homes to get
their product approved by the state. These dwellings are typically of closed-panel
construction that would be difficult to inspect at the installation site without removing
finish materials. They may be of panelized or modular type construction. They are
inspected in the plant by the Department of Commerce or a certified inspection agency.
Strict compliance assurance procedures must be followed by the manufacturer and
inspection agency.
This should not be confused with manufactured homes (formerly called mobile homes)
which are regulated by Federal Housing and Urban Development (HUD) rules. The state
-2004-20-29-
20.13(1)
mobile home program, also in the Division of Safety and Buildings, is under contract
with HUD to enforce the rules in Wisconsin.
For readers other than manufacturers, your attention is directed to ss. 20.13 and 20.15
which relate to on-site installation.
20.13(1) Manufacture and Sale
An approved Wisconsin modular home must display a Wisconsin Insignia to indicate that
the manufactured portion of the unit has been constructed and inspected in compliance
with the Uniform Dwelling Code.
Typical locations are on the electrical service box, under the kitchen sink, in the bathroom
vanity or in a closet. Following is a sample of an insignia.
Each unit is also required to bear a manufacturer’s data plate (see s. 20.14(6)(e)). The
data plate indicates the equipment furnished with the unit design loads and testing. This
information should be reviewed and compared with site requirements. If required testing
has not been performed in the plant, the system should be tested on site. The data plate
also indicates the unit serial number. This number and the Wisconsin insignia number
are necessary to track production records if a problem or question should arise.
Insignia Color is Red
In addition, the Department of Commerce is allowed to enter into reciprocity
arrangements with other states (see s. 20.14(7)) regarding modular homes.
20.13(2) Installation
On-site work for modular homes such as foundations, basements, heating systems,
electrical systems, plumbing systems, and additions are subject to the same plan submittal
and inspection requirements as site-built dwellings. This includes permit procedures and
-2004-20-30-
20.13(2)
permit seal issuance. See s. 20.09 (4) (a) of this commentary for a plan submittal
checklist for on-site work for manufactured dwellings.
Installation and connection details should be checked for conformance to the
manufacturer’s instructions. The installer is required to furnish the inspector with
installation instructions upon request.
Any damage to the manufactured portion of the dwelling as a result of transporting or onsite handling should also be investigated by the inspector. Any questions regarding the
repair should be directed to the manufacturer and the inspection agency. Major repairs or
modifications may require on-site inspection by the manufacturer’s inspection agency to
ensure compliance with the approved building system.
-2004-20-31-
20.13(2)
Modular Home Manufacturers Approved in Accordance with UDC Comm 20.14
December 2008
Name & Address
1.
All American Homes
551 15th Ave. S.E.
P.O. Box 219
Dyersville IA 520400219
Insp.
Agency
PFS
2.
Bonnavilla Homes
111 Grant St.
P.O. Box 127
Aurora NE 68818-0127
NTA
3.
Commodore Homes
1423 Lincolnway East
P.O. Box 729
Goshen IN 46528
Crest Homes
P.O. Box 1218
Middlebury IN 46540
PFS
5.
CSI Homes
P.O. Box 138
Cambridge IL 61238
PFS
6.
Design Homes
600 N. Marquette Rd.
P.O. Box 239
Prairie Du Chein WI
53821
PFS
7.
Dickinson Homes
1500 W. Breitung Ave.
P.O. Box 2245
Kingsford MI 498022245
PFS
8.
Dutch Housing
1500 N. Detroit St.
La Grange IN 46761
NTA
9.
Fairmont Homes
502 South Oakland Ave
Nappanee IN 46550
PFS
4.
10. Felsar Forest Products
Box 23
Winter WI 54704
PFS
11. Fleetwood Homes
1119 Fuller Dr.
Garret IN 46738
PFS
12. Fuqua Homes, Inc
2405 Industrial Dr.
Boonville MO 65233
PFS
13. Hart Housing Group
aka Forest River
Housing
P.O Box 406
Wakarusa IN 46573
NTA
14. Hi-Tech Housing Inc.
19319 C.R. #8
Bristol IN 46507
15. Homeway Homes
100 Homeway Court
Deer Creek IL 61733
TRA
16. Indiana Building
Systems
51700 Lovejoy drive
Middlebury IN 46540
TRA
TRA
PFS
17. Liberty Homes
NTA/P
dba Dorchester Homes FS
& Badger Built Homes
1 Factory St.
P.O. Box 228
Dorchester WI 54425
18. Manufactured Housing
Enterprises
09302 State Road 6
Bryan OH 43506
-2004-20-32-
PFS
20.13(2)
19. Madison Area Technical
College
3550 Anderson St
Madison WI 53704
Attn: John Stephany
20. New Era Building
Systems
451 Southern Ave
Strattanville, PA 16258
21. North American Homes
600 Marquette Rd.
P.O. Box 239
Prairie Du Chein WI
53821
Per
Unit
29. Stratford Homes
P.O. Box 37
Stratford WI 54484
PFS
30. Superior Homes
st
715 21 St SW
Watertown SD 57201
NTA
PFS
31. Terrace Homes
1553 11th Dr.
Friendship WI 53934
PFS
PFS
PFS
22. Patriot Homes-Crystal
Valley 10440 C.R. 2
Middlebury IN 465409630
NTA
32. Universal Housing
Systems
th
4265 N. 30 St
Milwaukee WI 53216
33. Vertical Works, Inc
3834 East Puetz Rd.
Oak Creek WI 53154
23. Pittsville Homes
Box C, Highway 80
South
Pitttsville WI 54446
PFS
34. Wausau Homes
P.O. Box 8005
Wausau WI 544018005
PFS
24. Redman Homes
308 Sheridan Dr.
Topeka IN 46571
NTA
PFS
25. Ritz-Craft Corporation
of MI
118 Deal Parkway, P.O.
Box 5
Jonesville, MI 49250
NTA
35. Wick Building SystemsMarshfield
230 E. Fourth St.
P.O. Box 530
Marshfield WI 54449
36. Wisconsin Homes
425 W. McMillan St.
Marshfield WI 54449
PFS
26. Shamrock Homes
1201 W. Markley Rd
Plymouth IN 46563
NTA
27. Skyline Homes
Hwy 61 N.E.
P.O. Box 590
Lancaster WI 538130590
PFS
28. Sterling Homes
P.O. Box 406
Wakarusa IN 46573
-2004-20-33-
PFS
20.14
Inspection Agencies
PFS Corporation
2402 Daniels St.
Madison WI 53704
608 221-3361
NTA, Inc
P.O. Box 490
Nappanee IN 46550-0490
219 773-7975
Radco
P.O. Box 812
Goshen IN 46527-0812
(574) 534-0244
T.R. Arnold & Associates
700 E. Beardsley Ave.
Elkhart IN 46515
574 264-0745
574 264-0740 fax
This list subject to change as approved manufacturers are added or deleted.
20.14 Approval Procedures
The Department of Commerce's UDC Program has an informational and submittal packet
available for dwelling manufacturers interested in our manufactured dwelling program. l
20.14(7) Reciprocity
Other states may have manufactured dwelling approval and inspection programs equivalent to
Wisconsin's. If a reciprocity agreement is in effect the states will accept dwellings approved,
inspected and provided with an insignia of the state of manufacture. The dwelling must be
inspected to conform to the code of the state where it will be located. Wisconsin currently has a
reciprocity agreement with Minnesota and thus recognizes dwellings bearing the “IBC” or
‘Industrialized Building Commission’ labels.
20.15 Effect of Insignia
A dwelling bearing a Wisconsin Insignia is presumed to be code complying. A local building
inspector may not require the opening up of closed walls or other components coming from the
plant. However, if noncompliances are otherwise noted, they should be cited by the inspector.
The Department of Commerce should be notified for further investigation at the manufacturing
plant.
20.15(3) Right to Install
A dwelling bearing a Wisconsin Insignia must be accepted by a municipality as would a site-built
home. It would be subject to any zoning requirements.
-2004-20-34-
20.18
Overview of Subchapters VI, VII & IX
These subchapters describe some of the special UDC administrative procedures. It is
worthwhile to briefly highlight the differences in the purposes of these administrative
procedures as well as other associated UDC procedures:
•
•
•
•
•
Engineered Design/Structural Analysis - This is a design that falls outside of the
prescriptive or cookbook design tables and specifications of the UDC. A local
inspector can accept them as long as the basic code requirements, such as design load
requirements, are met. Typical acceptable engineering standards are listed in ss.
20.24 and 21.02. Local inspectors may request state review as in s. 20.09(5)(a) of
this commentary.
Material Approval - Manufacturers and distributors of alternative materials or
methods often use this procedure. It can save time for all parties by substituting for
the Engineered Design/Structural Design procedure where the material or design will
be used repetitively in a number of dwellings.
Individual Variance - If an applicant cannot conform to a specific code section and
desires to provide equivalence to the code by other means, then a petition for
variance must be submitted to the state.
Municipal Variance - A municipality may submit a variance request to the
Department of Commerce when it believes that its climatic or soil conditions require
a different application of the UDC for homes in its jurisdiction. Such a variance
would apply to all homes in that municipality. There are currently none of these in
effect.
Appeals
• To Local Authorities - An appeal at the local level can only be on the basis of
improper enforcement of the code as written. It cannot be to request a variance
to a code requirement.
• To State Authorities - An appeal to the state can be for one of the following
reasons:
• An appeal of local enforcement after local appeal procedures have been
exhausted;
• An appeal of the state's determination on an individual variance;
• An appeal of the state's determination on a municipal variance.
Subchapter VI  Approval of Materials
20.18 Materials
Basic material performance standards are set forth in the various chapters of the code. All
alternate or new materials and new construction methods not covered by these standards may be
submitted and reviewed by the Department of Commerce for use in one- and two-family
dwellings. This may speed along the approval process for individual homes so that local
inspectors do not individually need to deeply review the acceptability of these alternate
materials and methods. Local inspectors may also review alternate materials, for specific
-2004-20-35-
20.19
projects, to determine if they meet the adopted engineering standards of the UDC.
Manufacturers or distributors request ‘Building Products Evaluations’ from the department. A
fee has been established by the department, and shall accompany the application. The
department will review all data, tests and claims of equivalent performance of the alternate
material or method with respect to the health, welfare and safety performance standards of the
code. Manufacturers or distributors may request a submittal information packet from our
division.
Manufacturers or distributors of reviewed materials should provide Department of Commerce
material evaluation numbers when requested. Copies of our material approvals are available on
our website. If there are any questions as to the acceptability of a material for use in one- and
two-family dwellings by a building inspector or manufacturer, please call the Department of
Commerce. You may view current material approvals on our website: www.commerce.wi.gov
under the one and two family program.
Subchapter VII  Variances, Appeals, Violations and Penalties
20.19 Individual Variance From a Specific Rule
It should be noted that only administrative code items may be petitioned for a variance. This
means that if an item is required by the state statutes (which may be repeated in the
administrative code), it may not be granted a variance. An example of this are minimum smoke
detector requirements.
An approvable variance application must demonstrate that the proposed design provides
alternative measures that provide an equivalent degree of health, safety or welfare. Economic
hardship, "it's not my fault," or "due to an error in construction" arguments themselves do not
justify a variance.
Variances are processed by the state only for dwellings originally built since June 1, 1980.
Variances for older dwellings, even though possibly subject to the UDC by local ordinances, are
processed by the municipality.
Question:
Answer:
How does one go about applying for a variance to the Uniform Dwelling Code?
All variance requests shall be submitted to the Department of Commerce via the
enforcing municipality, if applicable. A complete submittal includes an Application
Form (SBD-9890 (R. 11/2003)), including the Municipal Recommendation and the
required fees per Comm 2.52(2) (currently $125.00). A copy of relevant building
plans, sketches, photographs, or other documents clarifying the statements on the
application forms will be necessary in almost all cases. The municipality may also
charge a variance processing fee.
20.21 Appeals of Orders and Determinations
Individuals (owners and/or builders) have the right to appeal any municipal or Department of
Commerce order or determination. The procedures in appealing such orders or determinations
-2004-20-36-
20.24
are set forth in s. Comm 20.21. Note that an individual may not formally appeal a municipal
decision to Commerce until they have exhausted the municipal appeal process. Also note that
the administrative appeals process may not be used once an order has been referred to the
responsible legal authorities (city attorney, district attorney, Attorney General).
Occasionally, a building inspector's cited violations will be appealed to the local municipality
following these procedures. Appeals of whether a particular code section applies to a particular
situation may be decided locally.
The Department of Commerce welcomes enforcing municipalities to contact us to clarify code
requirements at this point or even before writing orders. Generally it is not desirable to refer
builders or designers to us directly regarding a specific project until the inspector first discusses
it with department staff.
However, appeals that require granting of a variance to a specific UDC requirement cannot be
approved by any municipality. All requests for a variance from the code must ultimately be
submitted to the Department of Commerce for approval, conditional approval or denial
(Comm 20.19). The Uniform Dwelling Code, in order to maintain statewide uniformity, did not
extend to the building inspectors and/or municipalities the authority to deviate by local variance
from specific code requirements on specific projects.
Since a municipality has the responsibility of making recommendations to the Department of
Commerce on a variance, it is certainly appropriate that the variance be first directed to the local
Inspection Department or Board of Appeals for comment.
20.22 Extensions of Time
Normally cited violations shall be corrected within 30 days after written notification in
accordance with s. Comm 20.10(1)(c). However, municipalities may grant extensions of time for
varying reasons.
20.22 Penalties
It is not the intent of the department to set or receive penalties or forfeitures for violations of the
code where municipalities are effectively administering and enforcing the Uniform Dwelling
Code by establishing their own remedies and penalties. A municipality exercising jurisdiction
should adopt ordinances for remedies and penalties for violations of this code.
Subchapter IX  Adoption of Standards
20.24 Adoption of Standards
All dwellings are required to be designed by the method of structural analysis or the method of
accepted practice outlined in each chapter of the code. Dwellings designed by the method of
structural analysis shall comply with the standards and manuals listed in this section. Other
acceptable engineering standards are listed in s. Comm 21.02. Refer to the later specific
-2004-20-37-
20.24
adopting section in the code to determine what portion is adopted. In general, where the standard
is more specific that controls over more general code language.
-2004-20-38-
Chapter Comm 21
Subchapter I  Scope
21.02 (1) (a) Dead Load of Insulation
To avoid ceiling gypsum board sag or related problems, attic insulation dead load should not
exceed gypsum board manufacturer's recommended capacity. This is especially true today
where thick attic insulation and 24-inch truss spacing are common.
For example, one manufacturer, United States Gypsum, in its Gypsum Construction
Handbook recommends that 3/8-inch gypsum board not be used to support insulation. They
also specify that their other panel thickness may support insulation given the following load
and framing spacing (gypsum board span) criteria:
Maximum Load
1.3 psf
2.2 psf
2.2 psf
Panel Thickness
1/2 inch
1/2 inch
5/8 inch
Framing Spacing
24 inch o.c.
16 inch o.c.
24 inch o.c.
Attic insulation materials vary in density and thermal properties. Therefore, the total weight
per installed R-value will vary depending on type, installation method and manufacturer of
insulation product. Some typical values are estimated below; check actual weights supplied
from your manufacturer or installer.
Density
Type
Cellulose
2.4 pcf
Blown Mineral Wool
1.2 pcf
Blown Fiberglass
0.6 pcf
Loose Fill Fiberglass
1.1 pcf
Fiberglas Batt R(19+19+13) 0.7 pcf
Rigid (expanded polystyrene) 1.8 pcf
Rigid (extruded polystyrene) 2.2 pcf
Spray (polyurethane foam) 1.9 pcf
Spray (open cell)
0.5 pcf
Mineral fiber (rockwool)
2.0 pcf
R/Thickness
3.6/inch
2.8/inch
2.7/inch
2.5/inch
3.2/inch
4.0/inch
5.0/inch
6.2/inch
3.3/inch
2.3/inch
R-38 Weight
2.1 psf
1.4 psf
0.7 psf
1.4 psf
0.7 psf
1.4 psf
1.4 psf
1.0 psf
0.4 psf
2.8 psf
R-50 Weight
2.8 psf
1.8 psf
1.0 psf
1.8 psf
0.9 psf
1.9 psf
1.8 psf
1.3 psf
0.6 psf
3.6 psf
From the data above, most typical R-50 installations would exceed the capacity of 1/2-inch
gypsum board on 24-inch o.c. framing unless the ½” gypsum board has been specifically
designed for that purpose. However, 5/8-inch gypsum board on 24-inch framing (typical
truss construction) would support most R-50 installations. Designers may want to check
with the specific gypsum board manufacturer for span/load capacities when using 24-inch
framing and high R-value cellulose installations. The above "USG" example indicates this
may cause overloading.
21.02 (1) (b) 2. Live Load - Snow
Exterior balconies or decks should be designed to withstand 40 PSF as the critical live load.
2009-21-1
21.02 (2)
The effect of drifting or sliding snow on a roof should be considered as a matter of good
design practice. However, the UDC only requires a 30 or 40 PSF snow load applied
uniformly to roofs. In complex roofs with side by side low-high portions or flat roofs below
sloped upper roofs, a designer may want to consider potentially higher snow loads in the
low roof areas where sliding or drifting snow may collect.
The UDC does not set lower snow live load values for roofs with glass or other slippery
surfaces. Comm 21.27(1)(c) does allow a reduced snow load for steeper roofs with slopes of
7 in 12 or greater. Otherwise, attached greenhouses, solar spaces, solar panels and other
similar roof construction should be designed to withstand 40 or 30 PSF for zone 1 or 2
respectively.
21.02 (1) (d) Fasteners
The fastener schedule in the appendix presents one means of showing adequate fastening to
meet the code in most typical designs with sawn lumber. However, it may not be sufficient
for certain designs, especially those using engineered lumber that can handle greater spans
and loads that those assumed in the appendix fastener table. Be sure to verify that the
fasteners provided will adequately transfer the greater loads that required special lumber.
21.02 (1) (d) Dwelling Anchorage
Question: When does a dwelling need to be anchored to the foundation?
Answer:
This section only discusses anchorage of the aboveground portion to the
foundation. This is to prevent potential movement of the upper level due to
wind pressure.
Section 21.18 requires the top of the foundation wall to have adequate lateral
bracing to the floor above to resist lateral soil loads, as through anchor bolts or
other means. Where failures of foundations walls have occurred in the past,
investigation has shown that many times damage could be attributed to lack of
lateral support at the top of the walls rather than to faulty material or
workmanship. In other cases, the use of a weak mortar in the masonry walls
was an important contributing factor. The practice of some contractors
backfilling basement walls before the first floor lateral support system is in
place contribute to failures.
In order for the floor system to provide lateral support where the joists are
parallel to the foundation wall, solid bridging or blocking needs to be installed
between the rim joist and adjacent floor joist.
21.02 (2) "Typical" Structural Analysis
Question: A builder submits a building plan and includes "typical" structural calculations.
Is there any time limit placed on the acceptability of such calculations?
Answer:
Usually the typical calculations correspond to a master plan of a home built
repetitively. When reviewing the building plans, you should verify that the
loading conditions, spans, member sizes, member spacing and lumber grade as
specified in the "typical" calculations are consistent with the plans. The use of
such typical calculations or span tables (as in the Appendix to Ch. 21) is
generally acceptable as long as the design criteria coincide with the building
2009-21-2
21.02
plans. There would be no time limit on the use of such calculations as long as
they do not conflict with the requirements of the current code. An update of
the calculations should be required if the code changes and different loads, load
duration factors or other design criteria become effective.
21.02 (2) Manufacturer's Installation Requirements
Section Comm 21.02(2), requires that all dwellings be designed by the method of structural
analysis or the method of accepted practice. It is accepted practice to install a material in a
manner required by the material's manufacturer, if the installation is regulated by the code.
A material installed in a manner that is inconsistent with the manufacturer's requirements
should not be allowed unless additional information is provided showing that the installation
will still meet the performance requirement of the code. An example is listed equipment--if
the equipment is not installed per manufacturer requirements, the acceptance provided by
the listing is not applicable. A manufacturer's installation requirement must also be checked
for compliance with the Uniform Dwelling Code. It is the responsibility of the builder to
have manufacturer's installation instructions available for review by the inspector (per
s. Comm 20.09) when a question of proper installation arises.
21.02 Engineering Terms Used in the Code or Referenced Standards
1. ALLOWABLE STRESS (F)
Determined by physical testing of wood specimens of different grades and species.
Tabulated value already has a built in factor of safety.
Historically done by visual inspection of wood for defects (knots, checks.....) =
Visual Graded.
Also can be done by machine by testing deflection-vs-load = Machine Stress Rated
(MSR).
2.
LATERAL SUPPORT
Structural bracing or interconnection that prevents movement of a structural
member in a specific direction, usually perpendicular to the direction that the main
structural member is providing support.
Examples:
bridging to joists
corner bracing to studs (let-in 1 x 4, metal straps, plywood panels)
subfloor to joists
sheathing to trusses
floor system to foundation walls
basement floors to foundation walls
3.
MODULUS OF ELASTICITY (E)
Ratio of stress/strain.
For a given force applied to a material, you can predict the deformation if you
know E.
4.
BENDING MOMENT (M)
Force x distance (inch-lbs).
Causes curvature deformation in beams or columns.
Causes tension and compression stresses in beams and sometimes columns.
2009-21-3
21.02 (3) (b)
5.
MOMENT OF INERTIA (I)
Used in the calculation of beam deflection.
Geometric property of a structural member.
I = bd3, inches4 (rectangular beam), b = width, d = depth
12
6.
SECTION MODULUS (S)
Geometric property of a structural component (beam, column . . .).
S = M/Fb, inches3
S = bd2 (rectangular beam), b = width, d = depth
6
7.
STRAIN
Deformation, (stretching, compaction, curvature) caused by an external force.
8.
STRESS* - Internal resistance to an external force.
- Generally in lbs/in2 (psi).
- Fb = bending stress;
Resists curvature due to bending moment (Force).
- Fc, Ft = axial compression or tension stress;
Resists perpendicular compaction or stretching due to a longitudinal force.
- Fv = shear stress;
Resists slippage in plane of the surface parallel to the end face of the beam.
*Capitol (F) denotes "allowable" stresses in a material samples as determined by testing
and adjusted by factors permitted by the applicable material standard. Small case (f)
denotes "actual" calculated stress of a structural member as based on design loads.
21.02 (3) (b) Structural Analysis Standards - Wood
The following code-referenced standards shall be used in the design of roof and floor
trusses.
The 2005 edition of the "NATIONAL DESIGN SPECIFICATIONS FOR WOOD
CONSTRUCTION" and its supplement, "DESIGN VALUES FOR WOOD
CONSTRUCTION," as published by the American Forest & Paper Association.
The "DESIGN SPECIFICATIONS FOR METAL PLATE CONNECTED WOOD
TRUSSES" TPI-02 as published by the Truss Plate Institute, Inc.
The department has determined that the design minimum live load in Table 21.02 for
ceilings with storage of 20 PSF applies to stick-built frame construction. Roof trusses
designed in accordance with TPI-02 for attic storage loading will meet the intent of the
code, only if such design criteria has been identified on the truss and drawings.
2009-21-4
21.02 (3) (b)
21.02 (3) (b) Outline of the National Design Specification (NDS)
This specification is adopted by the UDC s. Comm 20.24(2)(a) and s. Comm 21.02(3)(b).
The NDS is used for structural design of wood members as an alternative or in addition to
the prescriptive (accepted practice or "cookbook") standards in Ch. 21. It is the basis for the
development of the Fastener and Span Tables in Appendix App-17 of the UDC. Its
accompanying NDS Supplement provides allowable stress values depending on grade,
species and dimensions of lumber used. It is also the basis for "Design Values For Joist
And Rafters-Visual Grading" tables in Appendix App-17.
NDS Part I General Requirements for Structural Design
Includes guidelines for use of NDS considering the effects of:
- Bracing
- Connections at joints
- Adequate load assumptions
- Most conservative load combinations
-
The NDS is intended to be adopted by governing codes such as the UDC which
may prescribe the above minimum load and load combinations.
NDS Part II Design Values
Allows for modification of design stresses due to:
- Moisture conditions
- Temperature
- Preservative treatment
- Fire retardant treatment
- Duration of load.
Not all stress modifications are necessarily applicable to all beam and column installations.
Introduces the concept of a Load Duration Factor (LDF). The LDF will adjust allowable
stresses, generally upward, to recognize that wood is more responsive in resisting short term
loadings.
-
Floor Live Load = 1.0 (10 years)
Snow Load
= 1.15 (2 months)
Roof Live Load = 1.25 (7 day)
Earthquake, Wind = 1.6 (10 minutes)
Impact
= 2.00 (2 sec)
NDS Part III General Design Provisions and Formulas
1. Beam Design
Formulas listed in text (also see s. 21.22(3) of this commentary).
Notching of beams - limitations similar to UDC.
In general, the NDS assumes rectangular sections (sawn lumber) are used. Certain
modification factors can be used for other shaped (round) members. Also, other
shaped members will have different geometric properties that will alter the
"typical" formulas referenced in this commentary.
2009-21-5
21.02 (3) (b)
-
Beam formulas can be complicated by and thereby adjusted to compensate for:
- lack of lateral support
- relatively long beam length
- beam shape: round, rectangle, diamond
-
Beam design must also consider:
- Shear stress (fv), especially for heavily loaded members.
- Deflection considerations, especially for long spans or when the joist/beam
depth is relatively small.
2.
Column Design, Axial Compression (C)
Formulas listed in NDS.
Compression members can be horizontal or vertical (trusses).
Column design is a function of:
- Area
- Compressive Stress, fc
- Column length, l
- Column width, d
- Shape: round, square, tapered
- There is no one simple formula because of the many interrelated factors listed
above.
3.
Tension Members, Axial Tension (T)
Formulas listed in NDS.
Member design is a function of:
- Area
- Tensile stress, ft
- Usually end connections are most critical in design.
4.
Combined Axial (T or C) & Bending Stress
Common in truss design and pole buildings.
2009-21-6
21.02 (3) (b)
Snow, Dead
Load
M
T
Ceiling, Insulation
Load
Member
Stresses: Axial Tension and
Bending Moment
-
Formulas listed
Simplest case:
fb/Fb + ft(c)/Ft(c) less than or equal to 1.0
f = actual member stress
F = allowable member stress
-
This means that the sum of the percentage of actual bending tension
(or compression) stress plus the percentage of actual axial tension (or
compression) stress should be less than 100 percent of allowable
tension (or compression) stress. That is, allowable stress equals the
sum of the contributions from bending plus axial allowable stresses.
NDS Part IV Sawn Lumber
- Refers to design values given in NDS Supplement. Allowable stresses differ
depending on single-vs-repetitive member use.
-
Single member use
- individual member responsible for carrying entire load
- example: beam, column
- no "near neighbors" to share load
-
Repetitive member use
- bending members only
- spaced 24 inch on center or less
- not less that 3 in number
- joined by floor or roof decking to spread load to adjoining members
2009-21-7
21.02 (3) (b)
-
example: joists, rafters, trusses, built up beams, wall studs
NDS Part V Structural Glued Laminated Timber
(Also see further information in this commentary section.)
-
General Design Values based on visual and machine stress rated methods given
in Tables 5A, 5B, 5C and 5D of the NDS Supplement.
-
Design values can be modified due to service condition, etc., similar to those
specified in Part II.
-
Curved glued laminated members (arches) are possible and special consideration
is specified.
-
Glued laminated members subject to compression or combined tensioncompression are designed per Part III with some additional requirements.
NDS Part VI Round Timber Piles
- Rarely used for UDC construction.
-
Specifies types of preservative treatment, typical dimensional requirements per
American Wood Preservers Association (AWPA) and ASTM standards.
-
Design values and modification factors based on service condition, size and
condition of preservative treatment.
NDS Part VII Prefabricated Wood I-joists
- New section for NDS 2001 and often used in UDC construction.
-
Load duration factor is applicable, as well as beam stability factor
-
Repetitive member factor Cr = 1.0
NDS Part VIII Structural Composite Lumber
- New section for NDS 2001 and often used in UDC construction.
-
Load duration factor is applicable, as well as beam stability factor
-
Repetitive member factor Cr = 1.04 for 3 or more joined within 24”
NDS Part IX Wood Structural Panels
- New section for NDS 2001 and often used in UDC construction.
- Load duration factor is applicable
-
References American Panel Association (APA) documents for plywood, oriented
strand board (OSB) and composite panels for design and construction
recommendations of structural assemblies consisting of panel products.
2009-21-8
21.02 (3) (b)
NDS Parts X & XI Mechanical Connections & Dowel-type Fasteners
- Tables give design values, load per fastener, for:
- nails (common, box, etc., with minimum diameters)
- screws (lag, wood)
- bolts
- Minimum penetration of a lag screw is four times its diameter
- Minimum penetration of a lag screw is four times its diameter
- Edge distances, end distances, and spacing of nails and spikes shall be sufficient
to prevent splitting of the wood
- This information is used to develop the fastener table in UDC Appendix.
NDS Part XII Split Ring and Shear Plate Connectors
- Tables give design values, load per fastener, for:
- split rings
- metal plates
NDS Part XIV Shear Wall and Diaphragms
- New section for NDS 2001 and often used in UDC construction.
NDS Part XIII Timber Rivits, Part XV Special Loading Conditions, and Part XVI Fire
Design of Wood Members
- New sections for NDS 2001 and not often used in UDC construction.
NDS Supplement: Design Values
- Depending upon species, grade, and size classification, design values are
provided for various loading situations:
Fb - Allowable bending stress, psi
Fc - Allowable compressive stress (parallel to grain), psi
Fcl- Allowable compressive stress (perpendicular to grain), psi
Ft - Allowable tension stress, psi
Fv - Allowable shear stress, psi
E - Modulus of Elasticity, psi
- Some values also reprinted were based on the 1991 NDS.
Note: See Appendix for complete tables for all species and values.
Overview Of Important Issues Regarding Trusses
1. Per s. Comm 21.02(3)(f) and Table 20.24-13
Trusses should conform to TPI 1-2002, "National Design Standard for Metal Plate
Connected Wood Truss Construction."
2. Per s. Comm 20.09(5)(b) The designer may be required to submit plans showing the
truss design is consistent with or shows:
house framing plan
bearing and connection/anchorage details
design loads
top and bottom chord load
2009-21-9
21.02 (3) (b)
-
live, dead, wind load
concentrated or nonuniform loads
outside configuration of components
permanent bracing system if required
connector plate size per joint
3. Per s. Comm 20.09(6)(a)
The designer may be required to submit data including:
stress calculations (axial, bending, &/or combined)
species, grade, size of members
member forces
reactions
connector plate capacity required per joint
Additional Background Information Glue Laminated Timber(1)
1. Used for long spans, large loads and architectural effect.
1. Relatively thin laminations of wood combined to practically any length and size.
(d)
depth
}
Horizontal
laminations, 3/4 or
1 1/2 inches thick.
}
Higher strength
laminations for high
compression and
tension zones.
(b)
width - typically 3 1/8, 5 1/8, 6 3/4,
8 3/4 and larger
3. Relatively higher structural properties.
Laminations of high quality wood
Defects - Knots etc., spread out, not continuous for depth or width of member
Maximum 2600 psi bending stress = Fb, compared to 1900 psi for sawn lumber
4. Glue generally for wet use applications with some dry use glue allowed, but not
common.
5. Graded differently than sawn lumber.
-
24F indicates allowable bending stress = 2400 psi under normal conditions.
V1, V2 etc., refers to Visual Graded No. 1 or 2.
2009-21-10
21.02(3)(b)3.
-
E1, E2 refers to Machine Grading by testing the Modulus of Elasticity.
6. Some condition of use and load duration adjustment factors may apply.
7. Design properties are included in the NDS Supplement.
(1) Source: Breyer, Donald E., Design of Wood Structures, Mc Graw Hill, 1980.
21.02(3)(b)1.b. Re-Used Graded Lumber
Sound used lumber with grade marks still identifiable may be used for one- and two-family
dwellings as follows:
The published NDS allowable design stresses for the lumber species and grade
represent values for new lumber. To apply to used lumber, formerly these were to be
reduced to a 90 percent value. NOTE: For joists and rafters, use "Fb" for repetitivemember use under normal duration load conditions. These used, 90 percent reduced
bending values should not be increased using LDF's for snow or construction loading
conditions. The span tables for joist and rafters in the appendix of the code may be
used with the reduced design stresses.
Used re-sawn graded lumber must be graded based on the re-sawn and certified in
accordance with nationally recognized lumber grading rules for visually graded lumber
per ASTM D245. Agencies publishing grading rules are listed in the NDS "Design
Values for Wood Construction."
Sound lumber is defined as materials without structural damage such as splits, cracks,
gouges, saw, rot or insect damage and with notching and borings limited as follows:
21.02(3)(b)3. Native Sawn Ungraded Lumber
Sound, native, sawn un-graded lumber may be used for one- and two-family dwellings per
the NDS published allowable design stresses for the lumber species using No. 3 grade when
used for studs, stair stringers, rafters or joists and No. 1 grade for beams, posts or timbers in
lieu of certified graded lumbers. How may this section be applied?
Example #1:
1. I have an Eastern White Pine ungraded 2 X 4.. Can I use it as stud material?
2. Default Grade 3 can be applied to this lumber. In accordance with the lumber species and
grade table in the UDC code appendix, grade number 3 has an Fb of 605 psi.
3. This Fb value is greater than the stud grade for the same species (570 psi) required by
Table 21.25-A. Therefore, it is OK to use this for a stud.
Example #2:
1. I have an Eastern White Pine ungraded 2 X 10. Can I use this as floor framing material?
2. Default Grade 3 can be applied to this lumber. In accordance with the lumber species
and grade table found in the UDC code appendix, grade number 3 has an Fb of 445 psi and a
modulus of elasticity of 900,000 psi.
2009-21-11
21.02 (3) (b)
3. To determine the maximum permitted span for this lumber to be used as a floor joist, go
to UDC code appendix Table F-2.
4. The maximum span for a 2 X 10 with a modulus of elasticity of 900,000 psi spaced at
12” on center is 14’-11”.
5. Note, though, that the table minimum Fb for this member spaced at 12” o.c. is 777 psi.
This default Grade 3 lumber in question has an Fb of 445 psi. Therefore, this lumber may
not be used without structural analysis.
2007 Wisconsin Act 208 became law on April 22, 2008. This law permits individuals that
saw their own lumber on site to “self-grade” their lumber. The person that does the selfgrading must take a basic lumber grading program developed by the forest products
outreach program at the UW-Stevens Point. Go to the website
http://www.legis.state.wi.us/2007/data/acts/07Act208.pdf to get more information on this
act.
An alternative for lumber species not listed in the NDS "Design Values for Wood
Construction" and where nationally recognized allowable design stresses are not available,
structural testing of the materials will be required. Testing must be conducted by a
recognized independent testing agency in accordance with the appropriate ASTM load test
procedure. The cost of such testing shall be borne by the person applying for the building
permit.
The department will accept lumber species design stresses recommended by the U.S. Forest
Products Laboratory, Madison, Wisconsin.
Sound lumber is defined as materials without structural damage such as splits, cracks,
gouges, saw, rot or insect damage and with notching and borings limited as follows:
21.02 (3) (b) T-30 and T-50 Lumber
These 2" x 4" spruce-pine-fir lumber products designated by Weyerhaeuser as T-30 and T50 are taken from machine stress rated stock graded 1450-1.3E and 1800-1.6E, respectively.
These designations are intended to take advantage of better than average lumber within the
stress grade level as well as more accurate stress grading procedures and equipment.
The following allowable stresses (in PSI) associated with these products are approved for
use in Wisconsin.
Grade
T-30
T-50
Fb
1450
1800
Ft
800
1175
Fc
1150
1450
MOE
l,300,000
l,600,000
Any design values differing from the above are not to be accepted without
complete test data from an approved testing lab wherein ASTM procedures are
followed.
These products do not require a material approval as this is not a new construction
material or new assembly.
2009-21-12
21.02 (3) (g)
21.02 (3) (d) Concrete
Chapter 22 of ACI 318 provides minimum requirements for design and construction of
structural plain concrete members (those will no or little reinforcement) such as footings and
foundation walls. Unless foundation walls are alternatively designed and constructed in
accordance with accepted engineering practice, section 22.6.6.5 of this standard requires not
less than two No. 5 bars around all window and door openings. Such bars shall extend at
least 24 in. beyond the corners of the openings.
21.02 (3) (f) Roof and Floor Trusses
It is the responsibility of the inspector to verify conformance of the dwelling through the
plan review process and the inspection process. It is recommended that builders or truss
manufacturers demonstrate code conformance of their product to the building inspector in
one of the two following manners:
1.
DIRECT APPROVAL In this situation, the builder provides the structural drawings
and calculations for the truss or building component directly to the building inspector
for the inspector's review. The code does not require that structural drawings or
calculations be provided by a licensed professional engineer or architect. The building
inspector may review structural drawings and calculations for code compliance.
Structural drawings and calculations are commonly sealed & signed by a professional
engineer or architect and are generally considered as complying with the code.
All structural drawings and calculations shall conform to s. Comm 21.02(3) structural
analysis standards. Checking of input loadings, bearing support sizes and locations,
and even the span of the trusses should easily be checked to match the building design.
2.
MATERIAL EVALUATION NUMBER Under this method, the manufacturer of the
building component submits drawings and calculations to the Department of
Commerce. The Department would review the drawings and calculations and issue an
evaluation number to the manufacturer. The manufacturer provides the shop drawings
with the appropriate evaluation number to the builder and/or inspector. These
evaluation numbers will also be supplied on our website if available to the inspection
offices from the department by way of the Material Evaluation Notices. This will
serve as a means of cross-referencing the numbers to the manufacturer and the trusses.
With this method, the building inspector has to rely on the shop drawing provided by
the manufacturer to determine whether or not the product on the construction site
conforms to the standards. The inspector would compare the shop drawing to the truss
to verify that the same quality and size of lumber, connection plates, etc., were being
provided as were approved on the shop drawing. The background structural
calculations need not be repetitively submitted.
21.02 (3) (g) Log Homes
This section addresses log home construction; however, log homes are often engineered and
kit-produced by a manufacturer. In that case, their requirements should be followed when
stricter than the code minimums. The UDC also adopts the log home construction standards
2009-21-13
in Comm Tables 20.24-7 and 20.24-8. General guidelines for log homes that may be useful
to you can be downloaded or you can order the adopted standards from the organizations
referenced in the tables. The ICC standard is generally applicable to log structures, while
the ILBA standard applies only to construction using handcrafted, interlocking, scribe fit
construction.
21.03(1) Acceptable First Floor Exits
Question: Is it acceptable to use a ground floor exit door to help satisfy the requirement
for two exits from a first floor?
Answer:
Yes, assuming the two floors are connected with a stairway and the other
requirements are met. In this situation, the exit separation distance would be
measured from the middle of the first floor exit door to the middle of the top of
the stairway on the first floor.
Question:
Answer:
Are first floor bedrooms required to have egress windows?
No. The code indicates two exits are required from the first floor; however, if
the exit separation requirements of 21.03(1)(e) are not met then any first floor
bedroom would require egress windows.
21.03(1) Earth-Sheltered Dwellings
Per the definition of first floor in s. Comm 20.07(34e), there is always a first floor, so a
single-story (first floor) earth sheltered dwelling requires two exits per this section. Egress
windows may not be used to satisfy requirement unless it is a small dwelling. See sections
20.07(34e) of this commentary for further discussion.
21.03(1)(e) Separation of Exits
Note that these sections require the two required exits to be separated a distance of at least
one-third the longest diagonal measurement in plan view of that floor or at least 20 feet (see
diagrams).
GAR.
ss. Comm 21.03(1), (e) 1., & (e) 2.
2009-21-14
SEPARATION OF EXITS
21.03(2) Second Floor Bedroom Egress
Question: If one of the second floor bedrooms has a code-compliant exit door out of the
bedroom onto a deck or balcony, can the requirement for egress windows in the
other second floor bedrooms be waived?
Answer:
Yes, but only if the hardware on the bedroom door, which leads to the second
exit is incapable of being locked from the hallway that serves as the exit path
from these other bedrooms .See chapter 20.07 for ‘EXIT’ definition.
21.03(3) Acceptable Exits Above the Second Floor
Small third floor rooms specified under s. Comm 21.03 (3) (b) require only one stairway or
ramp that leads to the second floor or lower in the dwelling. If the dwelling is fully
sprinklered, only one exit is required from the third floor. Otherwise, only stairways or
ramps to the second floor or grade are acceptable to meet the two exit requirements. If an
exterior stair is used, access to it from the third floor shall be with a door and if the stairway
terminates at the second floor, then there must be a door leading back into the dwelling or a
code-compliant egress balcony to complete the exit path.
21.03(3) Exits from Attics
Question: Does the requirement for two exits for floors above the second floor apply to
walk-up attics?
Answer:
No - it would only apply to habitable spaces including offices, playrooms or
other conditioned spaces [see s. Comm 22.10 (3)] that may be occupied. Since
attics are not considered habitable spaces they need not have natural light and
ventilation nor multiple electrical outlets or lights unless they are used for
mechanical equipment or electrical equipment.
21.03(4) Exits from Lofts
A code-complying loft is not subject to the exiting requirements of the other subsections of
this section. In other words, a loft open to a first-floor or second-floor below, only requires a
single stairway or ladder (depending on area) to satisfy exiting. A loft bedroom or loft level
would not require an egress window but would require natural light and ventilation the same
as any other habitable space. See s. Comm 20.07(50) of the code and this commentary for a
discussion of what is considered "open to the floor below."
21.03(6) Bedroom Exit Windows
Question: Can egress windows be located in sitting or dressing areas of a master bedroom
suite?
Answer:
This section requires egress windows in some bedrooms. However, it does not
specify the location of the window within the bedroom itself. A sitting room or
area located in an alcove of a master bedroom is an acceptable location for the
bedroom egress window. The alcove can be considered part of the bedroom if
there are no doors obstructing communication between the two areas.
2009-21-15
Comm 21.03 (6)
Egress Window Dimensions
Minimum
20" wide x 24" high
or
24" wide x 20" high
SLIDER
DOUBLE HUNG
CASEMENT
AWNING
Clear Width
Measured to Edge
of
Sash Opened to 90
degrees
MAX 46"IF NO
STEPS OR
PLATFORM
MAX 60"
WITH STEP
OR
PLATFORM
UP TO 46”
Permanent
Step(s) or
Platform - Min. 9"
MIN 20” WIDE
2009-21-16
MAX
24"
Not Acceptable Due
To Operator Arms in
Opening
21.03(8) Balconies
Balconies not used for a required exit purposes may be greater than 15 feet above grade.
All guardrails for balconies more than 12" above grade are required to comply with
Comm 21.04(3) regarding height, in-fill or spindle and rail spacing requirements.
21.03(9) Split Level Dwellings
This section allows floor levels within 5 feet vertically of each other to be considered one
floor level for exiting purposes. This does not change the definitions of the floor levels
as set forth in s. Comm 20.07. Also the requirements of ss. Comm 21.03(1), 21.03(5)(b),
and 21.03(6)(b) for proper separation of exits apply to the combined areas of the floor
levels..
Also, any combined floor levels must all be within 5 feet of each other. In other words, a
floor level that is between two other floor levels, separated by more than 5 feet, does not
make all three levels into one even if exiting is from the middle level. However, the
middle level may be combined with only one of the other levels.
21.035 Interior Circulation
Question: What is considered a full bath for this section?
Answer:
The code is clear in requiring one full bathroom to be provided with a 2’-8”
wide door. A full bathroom would contain a lavatory, water closet and
bathtub or shower.
Question:
Answer:
Question:
Answer:
What use is an "accessible" bathroom or bedroom with a 2’-8” door when it
is on the second floor?
The intent of this section is to minimize future structural door framing
alterations necessary to make a dwelling accessible to a physically
handicapped resident. Obviously, further alterations would be necessary for
the second floor situation, such as a stairway chair-lift or platform lift.
Also, there may be temporary situations where a handicapped resident or
guest, with physical assistance, could still make use of these second story
rooms. "Accessible" does not always mean wheelchair-accessible.
Can a 2’-6” flush opening pocket door be considered accessible?
This section requires, where cased or uncased openings are provided in lieu
of doors, the clear width of passageway openings shall be at least 2’-6”
wide. Where a pocket door is installed into a cased opening, the 2’-6” width
requirement still applies. In this situation, the pocket door could not be
provided with any doorstops and must open at least flush with the cased
opening so that neither the door or trim infringe upon the cased opening
width.
The intent of this code section is to provide a minimum 2’-6” width for
disabled person use. Alternatively, a 2’-8” wide opening is required when
2009-21-17
swing doors are installed because of the door stops and door itself infringe
on the opening width such that the effective opening is 2’-6”.
Question:
Answer:
Question:
Answer:
Are interior doors required to separate rooms such as bedrooms or
bathrooms from the rest of the dwelling?
No, although it is common practice to have door separating these areas,
doors are not required. The minimum opening requirements in Comm
21.03 (8) must be met but doors or privacy hardware is not a code
requirement.
When these sections refer to a minimum door width of 2’-8”, how is it
measured?
The door itself should be measured - not the distance between jambs or
stops.
21.035(3) Clearance Between Cabinets & Appliances
The required 30 inches of clearance between major appliances and islands, walls or builtin cabinets is measured to the face of the cabinets, not including countertop nosings.
Unregulated
30”
21.04(1) Non-required Stairs
Although stairways to attics and crawlspaces are not covered by the code, other nonrequired stairs, such as a second stairway from the first floor to a basement, are covered.
Stairways are a major location of deaths and serious injuries in the home. Statistics from
the U.S. Consumer Product Safety Commission (CPSC) show that one in four people will
be injured and seek hospital treatment due to an injury related to stairways sometime in
their lives. In 1994, the number of injuries from stairs, ramps, landings and floors was
1,879,029. This was an increase over the previous year by 11 percent (200,000-plus
injuries), and was roughly equivalent to 19 percent of the total number of injuries
reported in all categories for that same year.
The CPSC also estimates that the cost of home injuries in 1994 was $94.3 billion. The
cost directly related to injuries from stairs, ramps, landing and floors was $17.5 billion.
Similarly, a study prepared for the U.S. National Bureau of Standards estimated that stair
riser/tread dimensions are factors in nearly 50 percent of all stair-related injuries in the
home.
2009-21-18
21.04(1)(b)2.
21.04(1) Exterior Stairs
Question: This section applies to exterior stairs but how far away from the dwelling
would this coverage extend?
Answer:
The stair requirements would apply to any steps necessary to get an
occupant free and clear of the dwelling and to grade, as stated in Comm
20.02(1)(g) Scope.
21.04(1)(a)2. Bathtub Platforms
Question: Do the stair code requirements apply to steps serving a bathtub platform?
Answer:
Yes, unless the stairs were manufactured as an integral part of the tub.
Where a step or steps are provided at a bathtub, whirlpool or hot tub, the
steps are required to have a minimum 9-inch tread and maximum 8-inch
riser. Where more than one step is provided, the steps need uniform risers
and treads. The rim of the tub should not be considered a step unless it is a
large area where occupants are likely to walk around the tub. Steps are not
required to be provided at the base of a tub, but due to damp slippery
conditions associated with tubs, steps that are provided should comply with
the code.
21.04(1)(b)2. Exterior Stairs to Basements
Question: Do bulkhead-type doors and stairways need to be code complying?
2009-21-19
21.04(2)(d)3.&4.
Answer:
No, they must be code complying only if they are used AS AN EXIT, not if
they are used as a service or non-required stairway. However, if they are
required for egress, then verify the following items:
• landings,
• handrails,
• stairway width,
• headroom, and
• stair treads and risers.
In the case of bulkhead-type doors and stairs:
• The headroom height may be measured with the doors open, since
the stairway is only usable if the doors are opened; and
• A landing is not required at the head of the stairway since this is
considered an interior stairway protected from the weather.
However, a landing is required at grade outside the door.
Regarding the door(s), they must meet the exit door requirements if this is a
required exit. That means it must be 2’-8” wide if there is a single door and
2’-6” each if there are double doors. If this is not a required exit, then no
minimum width applies. Door headroom, at the bottom of stairs, would
normally have to be in compliance with the required stairway headroom.
21.04(2)(c)3.&4. Winder Steps
SINGLE WINDER
MULTIPLE WINDERS
Equal Tread
Depths - Min. 9"
Equal Winder
Tread Depths,
With Min. of 7”
12”
12”
12”
12”
Measure to nearest wall,
skirt board or spindle
Measure to nearest wall,
skirt board or spindle
2009-21-20
21.04(2)(d)3.&4.
21.04(2)(d)3.&4. Planning for Stair Headroom
Maintain 6'-4" Headroom In
Required 3' Long Landing
Finished Stairwell Length (FSL)
Floor/Ceiling
Depth
Two Similar
Right
Triangles
Headroom
(Min. 6'-4")
Unit Rise
Max. 8"
Maintain
6'-4"
Headroom
In
Required
3' Long
Landing
Unit Run
Min. 9"
Headroom + Floor/Ceiling Depth (HFCD)
Unit Rise
So to solve for FSL, FSL = Unit Run x HFCD
Unit Rise
2009-21-21
Finished Stairwell Length(FSL)
Unit Run
21.04(2)(d)3.&4.
Straight Stairs
Samples and least costly requires a long hallway which may sometimes be a disadvantage.
May have walls on both sides (closed string) or may have open balustrade on one side (open
string).
Height
Floor to
Floor M
8'0"
8'6"
9'0"
Number
of
Risers
Height of
Risers
12
13
13
13
14
14
8"
7 3/8" +
7 3/8" +
7 7/8" –
7 5/16"
–
7 5/16" 7 11/16"
–
7 3/16"
+
7 3/16"
+
14
15
15
R
Width
of
Treads
T
Total
Run
L
9"
9 1/2"
10"
9"
9 1/2"
10"
9"
9 1/2"
10"
2009-21-22
Well
Opening
U
8'-3"
9'-6"
10'-0"
9'-0"
10'-3 1/2"
10'-10"
Minimu
m
Headroo
m
Y
6'-4"
6'-4"
6'-4"
6'-4"
6'-4"
6'-4"
9'-9"
11'-1"
11'-8"
6'-4"
6'-4"
6'-4"
8'-5"
9'-6 1/2"
9'-11
1/2"
8'-1"
9'-2 1/2"
9'-8 1/2"
8'-3"
9'-4"
9'-10"
21.04(3)
21.04(2)(e)1. Tread Height and Depth Uniformity
Within a stairway flight, the greatest tread depth may not exceed the smallest tread depth
by more than 3/8 inch and the greatest riser height may not exceed the smallest riser
height by more than 3/8 inch. Once an intermediate landing occurs, a new flight starts
and new riser and tread dimensions may be used.
Question:
Answer:
Question:
Answer:
How is tread and riser measured for the purposes of this requirement,
especially taking into account the variety of finish materials used?
The tread and risers should be measured prior to application of carpeting.
Measurements should be taken to hard surface finish materials. This
alleviates problems encountered when the homeowner changes carpeting
materials. If the carpeting is already in place, the inspector should estimate
the thickness of carpeting and padding to determine compliance. The
inspector should walk up and down the stairs, as well, to determine what, if
any, tripping or falling hazard exists.
At an exterior door (or an interior door, such as the 20-minute rated door,
between the house and garage) a threshold separates the main floor level
from the stair or landing, either up or down. Is the height of the threshold
included in the riser height when you are determining if all risers are
uniform?
No, you always measure from hard surface to hard surface. This means
from the floor level to the landing or tread, even if the threshold “could” be
stepped on, it is not included in the height of the riser. Remember that
carpeting is not a hard surface even if is indoor/outdoor type material.
21.04(3) Handrails or Guardrails
See handrail cross-section diagrams in the UDC Appendix (approximately page 140).
Question:
At the time of occupancy, a sliding patio door installed in an exterior wall is
viewed by the inspector without an exterior deck,landing, stairway or
2009-21-23
21.04(4)(a)
Answer:
Question:
Answer:
Question:
Answer:
platform. The floor to grade elevation difference is greater then 8 inches. Is
this okay since two other exit doors could provide exiting from the dwelling
and the elevation difference is less than 24 inches?
No. The presence of the door, whether required or not, is installed to allow
exiting and movement between areas. There is an elevation difference from
the floor to grade in the exit path so a stairway or landing platform is
required per s. Comm 21.04 prior to occupancy. However, if the door was
substantially fastened closed with hardware and screws that would not allow
it to be opened more then 4”, then it would not be considered a door and
steps would not be required in the interim until a proper exit path is
provided.
Does a non-required guardrail serving a porch less than 24 inches above
grade need to comply with the code?
This section does not require the guardrail where the porch is less than
24 inches above exterior grade; therefore the height and other specifications
are not required for the guardrail installed. The designer may still want to
install the guardrail per code to alleviate concerns that the installation of a
non-required guardrail meeting less than the minimum specifications may
provide a false sense of safety for the building occupants.
Does a window well require a guardrail around it?
No.
21.04(3)(c) Measurement of Grade Differences for Guardrails
If “X” is < 36”, and
“Y” is > 24”, then,
a guardrail is required on the
left-hand side of the landing.
“X”
“Y”
21.04(4)(a) Irregular Landings
Min. 36" - May deduct
up to 4-1/2" for max.
38” high newel post
Min. 26"
18"
18"
Measure to nearest wall,
skirtboard or spindle
2009-21-24
21.04(4)(c)
21.04(4)(a) Projections into Minimum Stair Landing Width
The 4 1/2-inch maximum allowed projection of handrails or trim into the width of
a stairway on each side also applies to both sides of a landing since the landing is
part of the stairway. Also see Comm 21.035(2)(b) infringements permitted at
hallways.
21.04(4)(c) Stair Landings at Sliding Doors
Question: Is a landing required at the top of a stairway leading to a sliding
door?
Answer:
No, if this is an interior door. The exception under s. Comm
21.04(4)(c)1.a., which applies here, eliminates the landing if the door
does not swing over the stairs. Obviously, a sliding door could not
swing over the steps. This exception applies to both opaque and
glazed doors.
It depends, if this is an exterior door, the exception under s. Comm
21.04(4)(c)1.c., eliminates the landing if there are no more than three
risers and if the door is a sliding glass door. Otherwise, a landing is
always required per the introductory paragraph.
Question:
Answer:
Is a landing required at an exterior, glazed, swinging patio door?
If the exterior grade elevation is more than 8 inches lower than the
interior floor elevation, a landing is required. The sliding glass door
exception does not apply to swing exterior glass doors regardless if
they swing in or out of the dwelling. The argument of the door being
glazed permitting occupants to see a elevation change or step
conditions on the other side of the door does not hold true due to
drapes or other visual obstructions frequently being provided on the
door.
2009-21-25
21.04(4)(c)
DOOR
MIN 3'
MIN 3'
Exceptions
Interior Stairs (Garages and protected porches are interior spaces):
SWING
DOOR
SWING
DOOR
SLIDING
DOOR
NO LIMIT
ON RISERS
MAX 2
RISERS
NO LIMIT
ON RISERS
FLOOR
Exterior Stairs
SWING OR SLIDING DOOR
SLIDING
GLASS
DOOR
(PRIME OR STORM)
MAX 3
RISERS
GRADE
MAX 8”
2009-21-26
GRADE,
LANDING OR
PLATFORM
21.05(3)
21.042(2) Ladder Treads
Ladder treads are measured the same as stairway treads - horizontally from nosing to
nosing.
21.042(6) (b) Top Ladder Tread
This section is requiring that the top tread's (first tread below the floor level) back edge
be at least 7 inches from the wall in front of it. This ensures adequate toeroom and still
allows a full depth tread.
21.05(3) Safety Glass
Safety glazing must now meet 16 CFR Part 1201. The use of glazing meeting ANSI
Z97.1 is no longer an acceptable safety glazing material. It is important to note that state
statutes s. 101.125 also requires safety glazing. In addition, the Federal Consumer
Product Safety Commission (CPSC) in its regulation 16 CFR Part 1201 sets a minimum
for safety glazing requirements for doors and tub & shower enclosures that states may
only exceed with their requirements. While most of the items covered by these
requirements are glazed in the factory, local inspectors may become involved when sitemade doors are used, re-glazing is done, old doors are reused, sidelights are site-installed
or when the manufacturer fails in its obligations. Following are some questions and
answers on these various requirements.
Question:
Answer:
Why is safety glazing necessary?
The CPSC found that prior to its rules in 1974 that approximately
73,000 injuries related to architectural glazing were treated annually in
hospitals nationwide. Almost half were under age 14. The worst accidents
are those where the victim breaks the glass on impact and then he or she
rebounds back. On the rebound, the shards of glass get caught under the
skin and then severely rip it as the victim continues rebounding.
Question:
Answer:
How can I identify safety glass?
It will normally have a permanent label in the corner stating that the glass
meets 16 CFR Part 1201. You may request documentation from the
manufacturer if the label is not present. Safety glazing is classified by the
manufacturer as either Category I for use only in doors where the glazing is
less than 9 square feet or Category II for all ther uses.
Question:
Answer:
What are the different types of glazing and which may be acceptable?
Tempered glass may be acceptable. It is produced by reheating glass and
then suddenly cooling it. It is four times stronger than regular annealed
glass. It cannot be cut after tempering so dealers will often need to custom
order it from a tempering facility. It breaks into small pieces when broken.
Laminated glass may be acceptable. It consists of two or more layers of
glass bonded to a tough resin interlayer. It can be cut or drilled.
2009-21-27
21.05(3)
Wired glass is generally not acceptable in areas where safety glazing is
required unless it is labeled as meeting CPSC 16 CFR Part 1201. It
would typically need an added layer of resin to meet that standard.
Heat-strengthened glass is not acceptable. It is produced similarly to
tempered glass but is cooled slower. As a result, it is only twice as
strong as regular annealed glass. It can be cut or drilled.
Annealed glass is not acceptable. It is regular glass that may also be
known as flat or primary glass. Also not acceptable are plate, float,
sheet and patterned glass. These are easily cut and drilled.
Plastic glazing is not considered glass so it is not subject to the safety
glazing requirements.
When safety glazing is required, all layers of a multi-layer assembly
(e.g., insulated glass) must be safety glazed.
Question:
Answer:
Is safety glazing required in glazed sidelight panels on both sides of a
sliding patio door unit which has one fixed and one operating panel?
Yes, the CPSC requires both panels of a patio door unit to be safety glazed,
whether they are fixed or operating. Therefore the Wisconsin code
requirement applies to glazed sidelight panels located on either side of both
patio door panels.
Question:
Answer:
Are these requirements retroactive?
While the UDC only applies to one- and two-family dwellings built since
June 1, 1980, both the CPSC and state statutory requirements are retroactive
to any re-glazing work done in all types and ages of structures.
Question:
Answer:
Can leaded, stained glass be used where safety glass is required?
Yes, based on the state statutes and CPSC regulations, this would be
acceptable.
Question:
Does the UDC require safety glass in panels or windows that come down
near the floor but not next to a door?
No, although the Commercial Building Code, various model codes and good
design would require safety glass in such situations, the UDC does not.
Answer:
Question:
Answer:
Is safety glass required in overhead garage vehicle-passage doors?
No. The safety glazing requirement is for doors that are primarily used for
human passage.
Question:
Answer:
Is safety glass required in skylights?
Not by the UDC or CPSC, although the Commercial Building Code requires
its use in skylights. However, the 30 or 40 PSF snow load requirement of
the UDC must be met.
2009-21-28
21.05(3)(b)
Question:
Answer:
Are glass blocks or glass block windows used in a tub or shower area in
compliance with the safety glazing rules?
Yes, first the individual units normally don’t exceed the minimum
dimensional requirements for safety glazed units. Secondly, the process
used in the manufacturing of glass block puts them into the category of a
masonry unit and therefore they do not need to meet the requirements for
safety glazing.
21.05(3)(b) Safety Glass Around Tubs
<5'
<3'
Drain or Bottom of
Tub
<3’
Plan View
21.05(3)(b) Safety Glass Around Stairs
1'
Min 3'
Deep
Landing
Stairway
Safety Glazing if glazing is ≤ 1'
horizontally from and ≤ 4' above
the adjacent tread or landing
2009-21-29
Landing
Min 3'
Deep
Landing
21.08
21.06 Ceiling Height
Question: Does a basement have to comply with the 7-foot minimum ceiling height
requirement?
Answer:
It only does in those ‘habitable’ areas of the basement that contain rooms
used for sleeping, living, dining, kitchens, hallways, bathrooms and
corridors. From a practical standpoint, most basements will contain some of
these uses initially or after the basement is finished-off in the future. Some
foresight by the builder or owner is advisable, since changing ceiling height
is not a practical building alteration.
Question:
Answer:
May a ceiling fan or light fixture encroach on the required ceiling height?
A ceiling fan or light fixture may encroach similar to a beam or ductwork no more than 8 inches below the required ceiling height; therefore, 6’-4”
minimum clearance maintained between fan or other obstruction and the
floor.
21.07 Attic and Crawl Space Access
Question: Can access be provided from outside the building, such as an outside vent or
scuttle?
Answer:
Yes, however, any area of 150 square feet or more must still comply with
the minimum opening size of 14” x 24”. This means if you have a home
with more than one attic space separated by a cathedral ceiling, two
openings would be needed.
Question:
Answer:
Do crawlspaces built with less than 18 inches of clearance or over concrete
slabs need access?
No access required; however, if area is outside the dwelling thermal envelope,
venting is required.
21.08 Zero Lot Line Dwellines
See appendix for explanatory drawing about adjoining, separate dwellings.
2009-21-30
21.08(1)(c)(d)2.
21.08(1)(d)2. Attic and Crawl Space Access
Question: What kind of hardware is necessary on an attic access door that is located in
the separation between a garage and dwelling area?
Answer:
The cover or door is installed so that it is permanent (non-removable) with
hardware to maintain it in a closed position with latching hardware to
maintain. Self-closing hardware is not required.
21.08(1)(c)(d)2. Attic and Crawl Space Access
Question: How do you measure the distances indicated in Table 21.08 regarding
dwellings and attached/detached garages and accessory buildings?
Answer:
Fire-rated construction may only be required in situations of a common
house/garage wall or of adjoining house and garage walls that are less than
10 feet apart when measured perpendicularly from the house walls.
Per Table 21.08, fire-rated construction would not be required if the distance
between walls is 10 feet or more. The fire-rated construction is required
only in those portions of either wall that does not meet the above test. In
attached connecting breezeways or porches where there is no common wall
but a common roof, the entire fire wall separation is required. This follows
from the requirement that any fire separation shall extend from the top of the
concrete or masonry foundation to the underside of the roof sheathing or
ceiling. (See diagrams.)
FIG. A
DWELLING
REQUIRED
FIRE
SEPARATION
WINDOW
GARAGE
PORCH
FIG. B
D
G
FIG. C
P
D
2009-21-31
≤5’
G
21.08(1)(c)(d)2.
FIG.
D
D
P
G
>5’
FIG. E
G
D
P
<10
FIG. F
D
G
<5’
FIG.
G
D
G
>5’
FIG. H
D
G
>5’
<10’
FIG. I
D
G
>10’
2009-21-32
21.085
Dwelling Unit separation from
foundation to roof deck
21.08(2)(b) Dwelling Unit Attic Separation
Duplex
Side one
5/8" gypsum wallboard or
equivalent on each side of the wall
Duplex
Side two
METHOD #1
Comm 21.08 (2) (b) 1.
Attic draft stopping in
line with unit separation
-
5/8-inch type "X"
gypsum ceiling
Dwelling Unit separation from
foundation to ceiling
3/8" wood structural
panel
1/2" gypsum board
- 5/8" gypsum wallboard or
equivalent on each side of wall
Duplex
Side one
Duplex
Side two
METHOD #2
Comm 21.08 (2) (b) 2
21.085(1) Fireblocking of Tubs and Showers
Question: How should tub/shower units be fireblocked?
Answer:
For most units, there should be no need for fireblocking since interconnected
vertical concealed spaces do not require fireblocking. However, if the unit
had a canopy with a dropped soffit, then the fireblocking requirements would
apply to the interconnected vertical and horizontal concealed spaces, similar
to kitchen cabinet soffits. Also, the floor below a tub should be fireblocked if
it allows air/fire passage between levels within concealed spaces.
21.085 Fiberglass Insulation as Fireblocking
2009-21-33
21.09
Question:
Answer:
Is fiberglass insulation acceptable as a fireblocking and draftstopping
material?
As a fireblocking material,yes. As a draftstopping material, no. This section
allows other noncombustible materials in lieu of the traditional 2 inch
nominal wood or drywall firestops. Unfaced fiberglass batt insulation has
passed the E-136 (ASTM) test for non-combustibility. Therefore, such
insulation will be allowed as firestopping if it is tightly packed such that it
will be held in place
2009-21-34
21.09
2009-21-35
Comm 21.11
21.09 Smoke Detectors
Question: If a contractor or owner wants to have additional smoke detectors over and
above the minimum required by the Code, can they be battery-operated or
must they be hard wired into the required system(s)?
Answer:
Yes, if an owner wants a battery-operated smoke detector in every room or
closet, they can do that.
Question:
Answer:
Should smoke detectors be connected to a separate, dedicated circuit or can
they be tied to any lighting or outlet circuit?
Unlike fire alarm systems in commercial applications, the Department’s
recommendation is to connect the smoke detectors to a common lighting
circuit and be connected ahead of any local switches. That way, if the
circuit breaker trips, the owner will be aware that his smoke detector and
alarms are not operational because his hallway or kitchen (etc.) lights aren’t
working.
Comm 21.095 Carbon Monoxide Detectors
See the code Appendix for new CO detector requirements for licensed tourist rooming
houses.
Comm 21.10 Protection Against Decay and Termites
Question: An interior wood frame wall is placed on a continuous concrete footing in
the basement and is used in place of a beam for support of the floor system
above. The top of the footing will be level with the basement floor. Does
the sole plate of this wall have to be pressure treated with a preservative or
be decay-resistant lumber?
Answer:
Subsection Comm 21.10 (1)(g) states that wood used in basements for
bearing walls shall comply. This is a bearing wall and, therefore, must
comply.
Comm 21.11 Foam Plastic Insulation Protection
The department has been asked whether foam plastic sheathing located on the gable ends
of an unoccupied attic must be directly covered with a thermal barrier. The foam plastic
is required to be separated from the living space by a thermal barrier. In this case, if a
thermal barrier is located on the ceiling, such as the interior gypsum drywall, the foam
plastic is adequately separated from the living space and no direct protection is required.
We have also been asked if foam plastic on the interior of a crawlspace needs to be
covered. If the crawlspace does not openly communicate with an adjacent basement or
other living space, then the floor sheathing is adequate to separate the foam plastic from
the rest of the dwelling. However, if the crawlspace adjoins a basement or other space so
that there was free air flow between the two, then the foam must be covered.
Another question has been raised about the use of foam plastic insulation on the interior
of return air ducts. Sections Comm 21.11 and 23.08 prohibit the placement of
unprotected combustible foam plastic on the interior of supply and return air spaces.
2009-21-36
21.15(2)(a)
Comm 23.08(2)(a) requires ducts to be constructed of or lined with a noncombustible
material. An exception is made for unlined wood joists or stud spaces. Therefore,
combustible foam plastics located on the interior of duct spaces must be protected by a
noncombustible 15-minute thermal barrier.
Finally it has been asked if foam insulation in attached garages needs to be protected.
Yes it does because the requirement applies to any space where occupants may be present
or to which they may be indirectly exposed.
An important exception to the protection requirement in the Celotex Thermax brand foam
insulation which has received a Wisconsin Building Materials Approval (#200614-I) to
be installed without protection. This is based on diversified testing that simulates actual
fire conditions.
Subchapter III  Excavations
21.125 & 21.126 Erosion and Sediment Control and Storm Water Management.
See the UDC Appendix for erosion control and storm water management information,
including references to DNR & DOT websites for design standards. Also see Commerce
– Safety & Buildings website for Soil Erosion program information, to get the latest
information on design and requirements during and after dwelling construction.
Subchapter IV – Footings
21.15(1)(e) Floating Slabs or Similar Shallow Foundations
Comm 21.15(1)(e) requires structures with frost foundations to be structurally isolated for
the entire building height from portions of the building structure constructed on floating
slabs. This is needed so that portions that do not move will not separate from those that
“float” under frost forces, as well as so that exits are not obstructed by relative movement
of dwelling portions. A structural engineer could have some details that will work for the
different types of materials used at these locations that need a different type of connector.
Slip-joints can permit vertical deflection to occur, while maintaining horizontal load
integrity of the structure. Load paths will be critical to determine what is acceptable there
and what will not be permitted for connections.
21.15(2)(f) Deck Footings
Decks that are used in the required egress paths, even though physically separated, must
comply with the UDC. Footings must be designed to carry the loads of the deck. They
may be supported by frost footings or by a floating slab per Comm 21.15(2)(e). If the
latter option is chosen, then care should be taken to avoid differential settlement or frost
heave that could block the egress path. For the latter concern, a stepdown may be
desirable.
21.15(2)(a) Unstable Soil
2009-21-37
21.15(2)(f)
Forming of a continuous footing is required if you encounter an unstable soil. Per the
note, an unstable soil would be one that can not support itself at an approximately 90
degree angle for the full depth of the footing. Examples of unstable soils would be sands
or gravels.
21.15(2)(e) Floating Slabs
Section 21.16generally requires a 48-inch footing depth to prevent frost damage. There
are some exceptions to allow lesser footing depths provided measures are taken to
prevent frost heave damage to the structure. Some measures which may be considered to
help prevent damage, if over and above the code minimum requirements, include:
• Verification of good soils (well-drained, granular) which may be less subject
to retaining water which may freeze and expand.
• Additional drainage at the affected footing in conjunction with good surface
drainage.
• Providing reinforcement in the affected footing and/or foundation wall.
• Providing reinforced perimeter grade beams in slab-on-grade construction.
• Providing a mechanical tie or continuous reinforcement to bind the stoops or
ramps to the foundation wall to resist relative movement. This would help
prevent obstruction of exit doors or gaps at the wall to stoop interface.
• Overdesigning the foundation or structure to recognize the potential for some
soil-caused deflection.
• Insulate the soil around the building perimeter with foam board laid
horizontally just below the ground surface.
Most times a qualified engineer should make the determination which of the above, or
other, measures is inherent in the situation or may be required to gain code compliance.
The engineer's report should be submitted to the local inspector for approval.
21.15(2)(f) Deck Column Footing Size
Deck footings are required [s. 21.225(2)] to be designed with a bearing area equal or
greater than the area required to transfer live and dead loads to the supporting soil
without exceeding the bearing value of the soil. In lieu of a designed footing, the code
required minimum size or a column footing of 24" x 24' x 12" thick should be used in
accordance with Comm 21.15(2)(b). In designing a column footing for a deck, the
following steps should be utilized:
1) Calculate the tributary area for floor and any roof area that the column carries.
2) Multiply the floor area by the code required live load and actual dead loads. Do the
same for any roof area.
3) Divide the total load from 2) by the this site’s allowable soil bearing value listed in
the Table at the end of s. Comm 21.15(3) to find the minimum footing size in
square feet.
2009-21-38
21.17
4) To provide adequate spread of the load through the concrete or gravel footer, its
thickness should be at least one-half of its diameter, but in no case less than 8".
21.16 Frost Penetration
Question: How does one determine if the local frost penetration is greater than the
48-inch minimum requirement by code?
Answer:
In most cases, you will find that the average frost depth does not exceed the
48-inch depth. A good source for the average local conditions of frost is to
check with the people involved with the installation of utilities or grave
digging.
21.16(2)(a) Frost Protected Shallow Foundations
Question: Are frost-protected footings allowed and what standards must be followed in
the construction of footings or slabs-on-grade without going below frost
levels?
Answer:
Yes. Frost-protected footings are allowed and by Comm 21.16(2)(a) are to
be designed to ASCE-32-01 standard adopted with 2009 code changes.
Frost-protected footings (FPF) is an internationally recognized and accepted
technique of protecting slab-on-grade foundations of heated buildings
against frost action. The FPFs use rigid horizontal perimeter insulation to
reduce heat loss from the ground around the dwelling. This heat keeps the
ground from freezing and frost action on the structure. The FPFs have been
used in Scandinavian countries since the 1950s and more recently in the
United States. See the UDC Appendix for a public domain version of this
design methodology. Note that if the heated building design is chosen, the
current and future owners need be made aware of the need to keep the
dwelling heated in the winter to avoid frost damage.
21.17 Determination of Drain Tile Need
Where municipalities exercise jurisdiction over requiring drain tile within their
community, they should provide sufficient notice to the building permit applicant by
indicating to the applicant at the time that the plans are approved how the municipality
handles enforcement of drain tile. This means that the municipality, plan reviewer, or
inspector should at the time the plans are approved indicate whether or not the
community will require drain tile to be provided with Comm 21.17, not require drain tile
to be provided, or will make a determination as to whether or not drain tile will be
required upon an inspection visit to the excavated site. This allows the communities to
either have a blanket policy of a requirement or non-requirement for drain tile, and still
allows them the flexibility to make that determination upon viewing the excavation,
wherein they can determine soil types and sometimes water elevation. It is the
department's position that for the drain tile requirement, the decision should be made as
early on in the permit, plan review, inspection process as possible and that decision
should be documented in review comments or inspection reports.
In response to questions and concerns regarding work continuing after an inspection has
not been carried out after the 2-days after date of notification requirement, municipalities
2009-21-39
21.17
and inspectors should inform the builder or owner that they are proceeding at their own
risk, and at the time the municipality or inspector makes the inspection they may still
require the drain tile to be provided in accordance with Comm 21.17.
A municipality may use various criteria other than a soil test report (per
s. Comm 21.17(1)(b) to determine where drain tile systems are required. Such criteria
may include county soil maps, direct observation of standing water in the excavation, and
experience with other sites in the locality. There is substantial discretion given to the
local inspector. It is recommended that the criteria for this local discretion, or municipal
policy, be uniformly applied within the municipality and expressed to builders before
construction, such as at permit issuance.
Where no local permit is required for an addition, the code requires the owner and builder
to install drain tiles where a soil test indicates periodic or seasonal groundwater at the
footing. Often times such homes are also in un-sewered areas. The soil test report for a
private sewage system will indicate depth to seasonal groundwater. This report may be
used to determine dwelling drain tile requirements if the house site is close to and is
similar in soil and drainage characteristics to the private sewage system on that site.
If a private sewage system soils report is not available or applicable, then the owner or
builder may retain a qualified soils consultant (engineer, certified soil tester) to determine
groundwater depth or rely on the experience of other projects in the area, if relevant.
TABLE 1
TYPES OF SOILS AND THEIR DESIGN PROPERTIES
Soil
Group
Soil
Allowable
Drainage
Front
Unified Soil
Classification Description Bearing in Characteristics2 Heave
System
Pounds Per
Potential
Square Foot
Symbol
with
Medium
Compaction
or Stiffness4
GW
Well-graded
8000
Good
Low
gravels,
gravel sand
mixtures,
little or no
fines.
2009-21-40
Volume
Change
Potential
Expansion
Low
21.17
Soil
Group
Group I
Excellent
Unified Soil
Soil
Allowable
Drainage
Front
2
Classification Description Bearing in Characteristics
Heave
System
Pounds Per
Potential
Symbol
Square Foot
with
Medium
Compaction
or Stiffness4
GP
Poorly8000
Good
Low
graded
gravels or
gravel sand
mixtures,
little or no
fines.
SW
Well-graded
6000
Good
Low
sands,
gravelly
sands, little
or no fines.
SP
Poorly5000
Good
Low
graded
sands or
gravelly
sands, little
or no fines.
GM
Silty
4000
Good
Medium
gravels,
gravel-sandsilt
mixtures.
SM
Silty sand,
4000
Good
Medium
sand-silt
mixtures.
GC
Clayey
4000
Medium
Medium
gravels,
gravel-sandclay
mixtures.
SC
Clayey
4000
Medium
medium
sands, sandclay
mixtures.
2009-21-41
Volume
Change
Potential
Expansion
Low
Low
Low
Low
Low
Low
Low
21.17
Soil
Group
Group II
Fair to
Good
Group III
Poor
Unified Soil
Soil
Allowable
Drainage
Front
2
Classification Description Bearing in Characteristics
Heave
System
Pounds Per
Potential
Symbol
Square Foot
with
Medium
Compaction
or Stiffness4
ML
Inorganic
2000
Medium
High
silts and
very fine
sands, rock
flour, silty
or clayey
fine sands
or clayey
silts with
slight
plasticity.
CL
Inorganic
2000
Medium
Medium
clays of low
to medium
plasticity,
gravelly
clays, sand
clays, silty
clays, lean
clays
CH
Inorganic
2000
Poor
Medium
clays of
high
plasticity,
fat clays
MH
Inorganic
2000
Poor
High
silts,
micaceous
or
distomaceo
us fine
sandy or
silty soils,
elastic silts.
2009-21-42
Volume
Change
Potential
Expansion
Low
Medium1
to Low
High1
High
21.17
Soil
Group
Unified Soil
Soil
Allowable
Drainage
Front
2
Classification Description Bearing in Characteristics
Heave
System
Pounds Per
Potential
Symbol
Square Foot
with
Medium
Compaction
or Stiffness4
OL
Organic
400
Poor
Medium
silts and
organic silty
clays of low
plasticity.
Group IV
OH
Organic
-0Unsatisfactory
Medium
Unsatisfact
clays of
ory
medium to
high
plasticity,
organic
silts.
Pt
Peat and
-0Unsatisfactory
Medium
other highly
organic
soils.
1
2
3
4
Volume
Change
Potential
Expansion
Medium
High
High
Dangerous expansion might occur if these two soil types are dry but subject to future
wetting.
The percolation rate for good drainage is over 4 inches per hour, medium drainage is
2 to 4 inches per hour, and poor is less than 2 inches per hour.
Building code allowable bearing values may differ from those tabulated.
Allowable bearing value may be increased 25 percent for very compact, coarse
grained gravelly or sandy soils or very stiff fine-grained clayey or silty soils.
Allowable bearing value shall be decreased 25 percent for loose, coarse-grained
gravelly or sandy soils, or soft, fine-grained clayey or silty soils. To determine
compactness or stiffness to estimate allowable bearing capacity, measure the number
of blows required to drive a 2-inch outside diameter, 1.375-inch inside diameter splitbarrel sampler 1 foot into the soil by dropping a 140-pound hammer through a
distance of 30 inches.
Question:
Answer:
If a drain tile “sock” is used, can I eliminate some or all of the coarse
aggregate?
No, the tile “sock” doesn’t replace any of the coarse aggregates function and
therefore, if used, is only an added safe guard against fines clogging the tile
weeps. With some types of soils the “sock” actually will hold certain types of
2009-21-43
21.17
fines and can cause basement water problems, so it is not recommended to
use this type of ‘socked’ tile within those soil types having those fines.
21.17 Drain Tile Materials and Installation Requirements
A properly functioning drain tile system will lower the water table (seasonal or longer
term) to the level of the tile installation in the immediate vicinity of the foundation wall.
This is important not only to achieve a relatively dry basement, but to maintain the
structural integrity of the home. A saturated soil is not only heavier than dry soil, but it
also has less internal soil friction that normally helps restrain lateral soil flow. Therefore,
the potential lateral pressures exhibited by saturated soils are significantly greater than
well-drained foundation backfill. Also a well-drained soil is less likely to frost heave
when frozen.
The tile, backfill, and discharge systems are designed to maximize drainage and minimize
potential siltation and overload of the system. A well-graded gravel bed and porous
backfill are important for proper drain system operation. Also, per s. Comm 21.12, the
grade around the dwelling should slope away to minimize the need for the drain tile to
handle surface water surcharge.
This office has received some complaints about sump pump systems operating
continuously. Contrary to the complainants' concerns, this is usually evidence of a
properly functioning system. The real problem is that groundwater in the area is at a
relatively shallow depth, local soils are porous, or both. This results in a high volume of
flow. These are conditions that should have been considered in making the decision
where to site the building by the owner and builder.
Such situations normally occur in lowland areas, where water tables are perched above
poor drainage strata, where surface drainage is bad, or where soils are very porous
(fractured limestone, gravels, some sand) that allow easy lateral soil water movement.
Zoning laws and subdivision ordinances more appropriately regulate whether certain
parcels of land should be developed and what floor elevation is required given these
conditions. However, zoning codes may not further regulate construction of the
foundation drainage systems.
Care should be taken not to allow sump discharge to cause erosion which would result in
sediment being deposited off site.
Wisconsin Plumbing Code in Comm 82.36(8)&(4) should be referenced in design of
sumps and discharge to surface where a storm sewer is not available.
The bleeders do not need to be connected to the interior and exterior drain tiles with
connectors – they may be butted to the tiles and have piece of membrane material, such
as building felt, placed over the gap to kept foreign material out.
2009-21-44
21.17
Question:
Answer:
Question:
Answer:
What is the proper location for drain tile at the footing level or on the
footing?
Drain tile is to be placed AT the footing level, not setting on the footing, as
the code is specific in Comm 21.17(3)(d)5. that the tile must set on 2 inches
of coarse aggregate and be covered with at least 12 inches of coarse
aggregate.
The code talks about the placement of drain tile on 2 inches of coarse
aggregate and being covered with 12 inches of coarse aggregate; but how
much coarse aggregate is to be placed on the side of the tile?
As the code states “covered with at least 12 inches of coarse aggregate,” this
includes the outside or side exposed to earth of the tile as well as the top.
Normally since one side of the tile (connected to the bleeders) is up against
the footing, only the top and side needs the 12 inches of cover.
2009-21-45
21.17
If no sill plate
Option
if slab not provided
3
If provided
If clay soil or drain tiles
2009-21-46
21.18(1)
Subchapter V  Foundations
21.18(1) Foundation Wall Lateral Support
Question: Why is lateral restraint required for foundation walls?
Answer:
All of the UDC concrete and masonry foundation wall tables are based upon
the assumption of lateral support at both the base and top of the walls.
The base of the wall typically is restrained by the floor slab or by the
footing with a keyed joint or rebar. The top edge of the foundation wall
may be restrained by the first floor through mechanical fastening or ledger
blocking. (Ledger blocking alone will not satisfy the dwelling anchorage
requirement of s. 21.02(1)).
Section 21.18(1)(c)&(d)2.a. requires that lateral restraint shall be continuous
from the wall to the plate to the restraining floor system. This will normally
require that solid bridging or blocking be installed between the rim joist and
adjacent floor joist that run parallel to the foundation wall to transfer the
loads on the wall.
Joists
Diagonal Bracing
OR Blocking @ max
32" o.c. spacing
Another method would be to furr the inside of the foundation wall with 2 x
4s or an engineered system secured to the joists and bearing against the
foundation wall or foundation wall footing.
A special case arises where the fill around a foundation is uneven, as in a
walkout basement. In this case the soil pressure on either side of the house
is not balanced, thereby possibly causing lateral racking movement of the
foundation and floor system. To resist this, additional lateral support by
rigid (plywood sheathed) interior cross walls or by pilasters may be needed.
2009-21-47
21.18(2)
FOUNDATION LATERAL RESTRAINT
Joist
2 x 6 sill plate, joist nailed to
plate with 2-16d or 3-8d nails,
1/2” anchor bolt embedded in
fully grouted top course.
7 feet soil unbalanced
fill, at 30 pcf equivalent
fluid pressure equals
214 lbs per foot lateral
load at top. (8-foot wall)
In addition to bolts, other means such as straps or engineered connections may be used to
provide lateral restraint to the top of the foundation wall.
21.18(2) Concrete Foundation Walls
Question: Is a 6-inch thick concrete foundation wall acceptable for supporting a 2 x 6
frame wall? The thickness of the frame wall with sheathing, siding, and
drywall will exceed the 6-inch foundation wall thickness.
Answer:
“In no case shall the thickness of the foundation wall be less than the
thickness of the wall it supports.” This requirement refers to the width of
the structural members of the supported wall. In the wall in question, only
the 2 x 6 framing (5.5 inches) are considered structural supporting members,
therefore the proposed wall is acceptable.
Question:
Answer:
What does the term nominal wall thickness mean in Table 21.18-B?
This term was used for when a piece of lumber was used to set the thickness
of the wall. That lumber may not have been the full 8 inches in width but
had an actual thickness of 7.5 inches at one time. Currently, for softwood
lumber of a nominal thickness of 8 inches, the actual thickness can be 7.25
inches. Although it is recommended that the full thickness specified in the
table be used, the department will permit a wall to have an actual thickness
2009-21-48
21.18(2)
less than that specified in the table but it may not be reduced by more than
½ inch.
Question:
Answer:
Are there situations where the department will allow unreinforced concrete
supporting walls thinner than specified in Table 21.18-B?
Yes, the code allows 6-inch unreinforced concrete walls to be used provided
the fill is within 12 inches of being evenly balanced on both sides of the
wall. The top of any concrete slab and the finish grade is used to determine
this measurement, such as in an attached garage situation or slab-on-grade
dwelling.
Table 21.18-B was developed to assist in determining the maximum height
of unbalanced fill that may be placed against a basement wall. The Uniform
Dwelling Code has never dealt directly with the issue of wall thickness
where the fill is balanced on both sides. During a past code update cycle,
the entry in the table for 6-inch walls was deleted because the American
Concrete Institute no longer allows unreinforced foundation walls or
exterior basement walls less than 7.5 inches thick. However, section 7.1.6.2
of ACI 318.1-1989 allows bearing walls to be a minimum of 5.5 inches
thick. With the fill balanced to within the 12-inch condition imposed above,
the wall will be considered a bearing wall rather than a foundation or
exterior basement wall. A 12-inch variation will still allow flexibility in
grading without necessarily mandating the decay protection of wall
structural members. Current ACI 318-2005 section 14.5.3.2 empirical
design does not permit less than 7.5” thick basement or foundation walls.
Question:
Answer:
What strength of concrete is a "five-bag mix"?
The strength of concrete is dependent upon a number of factors including
the cement-water ratio involved in the mix. A five-bag mix means that 470
lbs. of cement is used per cubic yard of concrete. Without knowing how
much water is also used per cubic yard of concrete, the actual design
strength of the concrete cannot be determined. Concrete suppliers should
have their design mixes tested prior to field use per the American Concrete
Institute (ACI) specifications. (See following section.)
Concrete Foundation Walls (Concrete Quality)
Compressive Strength of Concrete
The average strength of concrete produced must always exceed the specified value of
concrete strength (f'c) that was used in the structural design phase. This is based on
probabilistic concepts, and is intended to ensure that adequate strength will be developed
in the structure.
Acceptable Practice for Concrete Design
The specified strength of concrete for foundations and footings in one- and two-family
dwellings shall be at least 2,500 psi per s. 4.2 of ACI 318.1-89, Plain Concrete Code.
2009-21-49
21.18(2)
The height of 3,000 psi concrete foundation walls shall be governed by Table 21.18-B or
alternately, for greater or lesser concrete strengths, through engineered design. It is noted
that Table 21.18-B assumes the wall has lateral support at both top and bottom.
Proportioning on the Basis of Field Experience
For establishing concrete proportions, emphasis is placed on the use of laboratory trial
batches or field experience as the basis for selecting the required water/cement ratio. If
an applicable standard deviation for strength tests of the concrete is known, this
establishes the target strength level from which the concrete must be proportioned.
Otherwise, the proportions must be selected to produce an excess of target strength
sufficient to allow for a high degree of variability in the strength tests.
Where the concrete production facility has a record based on at least 30 consecutive
strength tests representing similar materials and conditions to those expected, the strength
used as the basis for selecting proportions shall exceed the required specified strength of
concrete (f'‘c) by at least:
TABLE A. REQUIRED OVERDESIGN
Standard Deviation (psi)
Under 300
300 - 400
400 - 500
500 - 600
Over 600
Unknown
Required Average (psi)
f’'c + 400
f’'c + 550
f’'c + 700
f’'c + 900
f’'c + 1200
f’'c + 1200
The indicated average strength levels are intended to reduce the probability of concrete
strength being questioned on any of the following usual bases: (1) too many tests below
specified f'c; (2) strength averaging below specified f' for an appreciable period (three
consecutive tests); or (3) an individual test being disturbingly low (more than 500 psi
below specified f’'c).
Proportioning on Basis of Acceptable Practice
If test data is not available, the following water/cement weight ratio may be used to
determine acceptable concrete strength.
3000 PSI concrete use 0.58 water/cement ratio
The following tables give guidelines for proportioning a mix of 1 cubic yard to develop
acceptable strength levels. Recommended slump for footings, foundation and slabs is
between 1 and 3 inches.
2009-21-50
21.18(3)
TABLE C APPROXIMATE MIX FOR SLUMP OF 1-2 INCHES
3000 PSI
Size
Aggregate
1/2"
1"
1 1/2"
2"
Water
Lbs.
335
300
275
260
Gallons
40
36
33
31
LB. of
Cement
578
517
474
448
94#
Bags
6.2
5.5
5.0
4.8
Percent*
Volume
of Coarse
Aggregate
50-60
64-72
68-76
71-79
TABLE D APPROXIMATE MIX FOR SLUMP OF 3-4 INCHES
3000 PSI
Size
Aggregate
1/2"
1"
1 1/2"
2"
Water
Lbs.
365
325
300
285
Gallons
44
39
36
34
LB. of
Cement
629
560
517
508
94#
Bags
6.7
6.0
5.5
5.4
Percent*
Volume
of Coarse
Aggregate
50-60
64-72
68-76
71-79
*Percent of coarse aggregate will vary with different fineness moduli of sand.
21.18(2) & (3)(a) Dampproofing
Question: Could you clarify the UDC requirements for waterproofing of poured
concrete foundation walls?
Answer:
This section only specifically addresses dampproofing of masonry
foundation walls. Section Comm 20.24(2) adopts American Concrete
Institute’s Standard ACI 318-05 for reinforced and plain concrete. This
standard does not mention waterproofing requirements. In summary, there
are no requirements for waterproofing of poured concrete walls in new oneand two-family dwelling construction.
Question:
Answer:
Does a masonry foundation wall have to be dampproofed before the
insulation is applied?
Yes, this section requires dampproofing of masonry foundation walls of
basements. The exterior applied insulation may then be installed. Alternate
systems do exist that use a layer of insulation. These need a Wisconsin
Building Material Approval or show equivalency with the code's
dampproofing requirements.
21.18(3) Masonry Foundation Walls
2009-21-51
21.205
In addition to Tables 21.18-B, C, D, or E, designers may use two alternative methods of
designing masonry walls.
1. Builder may design a reinforced wall design using structural analysis per s. Comm
21.18(2) and s. Comm 21.02(3)(e) "Concrete Masonry Handbook" or other accepted
engineering standard.
2. Builder may design using IBC 2109 of the Commercial Building Code as an
engineering standard. This "Empirical Method of Design" could be used as a
structural design aid per s. Comm 21.18(2).
21.18(4) Wood Foundations
A copy of the Permanent Wood Foundation Design Specification, ANSI/AF&PA PWF2007 may be obtained from the:
American Forest & Paper Association
1111 19th Street, NW Suite 800
Washington, DC 20036
(202) 463-2700 · info@afandpa.org
The UDC also permits the use of the Permanent Wood Foundations Design and
Construction Guide published by Southern Forest Products Association through the
Southern Pine Council. You may view and download a copy of this guide for free by
accessing their website www.southernpine.com .
Subchapter VI  Floors
21.203 Garage Floors
Question: Can the garage floor be at the same elevation as the finished floor of the
dwelling or is a step or landing required in the garage at a door between the
two?
Answer:
The code doesn’t require an elevation change between the garage floor and
the dwelling floor, only that the garage floor slope to the main exterior
opening or floor drain. Some local ordinances required a step, but no
national building codes have required a step there. In fact, builders who are
concerned with handicap accessiblity are promoting the same height floor
level for garages.
Question:
Answer:
What is the minimum pitch of the garage floor?
The code is silent on this and doesn’t prescribe the degree of pitch, only that
it must have a slope to provide drainage. A suggested rule of thumb for
concrete flat work is 1/8 inch drop per foot of run.
21.205 Wood Floors in Contact with the Ground
Such loors would also have to comply with Comm 21.10(1)to(5).
2009-21-52
21.22(3)
21.22(1) Floor Joist Design
Question: Does the deflection of floor joists have to be limited to the L/360 as shown
in the upper left corner of Table J-1 found in the code appendix.
Answer:
There is no requirement in ch. Comm 21 stating what the maximum
deflection of structural members must be. Deflection would, therefore, be
controlled indirectly through accepted engineering practice. Also, there is
no rule in Ch. Comm 21 which specifically states that deflection in Table J1 is part of the rule. All appendix tables are deemed to meet the minimum
standards.
22.22(1) Floor Joists and Sill Plates
Question: A wood floor joist system is resting on a sill plate which in turn rests on a
hollow concrete masonry foundation. Does the top course of masonry need
to have all cores and joints filled with mortar?
Answer:
Per s. Comm 21.22(1)(d), the cores of the blocks need not be filled as long
as a sill plate is as wide as the block itself is used. If a sill plate is smaller
then the width of the block or if a sill plate is not used, then all the cores
must be filled.
21.22(3) Steel Beams
Question: Please explain the terminology for steel beams in Table 21.22-A1.
Answer:
A-36 steel refers to the strength of the steel. It has an allowable tensile yield
strength of 36,000 pounds per square inch. Most beams are now A-50 steel.
The designations W and M refer to the standard cross-sectional shapes of
steel beams. The term I beam is no longer used, but does describe the
general shape of these beams. The major differentiating characteristics of a
beam are its top and bottom flanges which are horizontal and the vertical
web which separates the flanges. The specific descriptions are:
"W" - The top and bottom flanges are parallel to each other. Previously
called a wide flange beam in some cases.
"M" - Cannot be classified as a W or S shape. Sometimes referred to as a
junior I beam previously.
It is always best to get the actual shape designation from the suppliers.
The two numbers after the shape designation (W, M) provide (1) the overall
depth of the beam section and (2) the weight of the beam itself in pounds per
lineal foot.
So a beam designated as a W 8 x 15 has a W shape with relatively wide
flanges, a depth of 8 inches and weighs 15 pounds per lineal foot.
2009-21-53
21.22(3)
Question:
Answer:
Table 21.22-A1 gives sizes for beams when conventional framing is used.
Table 21.22-A2 gives sizes of wood beams when truss roofs are used. Are
there any tables that can be used for steel girders and beams when using truss
roofs?
The correct size of a steel beam can be obtained through use of the Steel
Construction Manual published by the American Institute of Steel
Construction, Inc. This is the same organization that publishes the standard
as adopted in s. Comm 20.24(2). This manual contains tables covering
different sizes and shapes of steel beams and specifies the maximum load the
beam can carry for a certain span. Table A of the following commentary
section (21.22(3)) can be used to determine the actual load on the beam. In
order to determine the total load on the beam, the actual load on the beam in
pounds per lineal inch as calculated by Table A must be multiplied by the
number of inches between the supports. The table found in Chapter 2 of the
Steel Construction Manual can then be used by selecting a beam and then
comparing the actual load on the beam calculated with the maximum
allowable load of the beam. There are also structural software programs that
may be used.
21.22(3) Wood Girder and Beam Design
The beam design tables as given in the Uniform Dwelling Code may be used for the
design or analysis of simple span timber beams and headers with uniformly distributed
loads.
The structural analysis for simple beams and headers are based on the following formulas:
BENDING
M = w(1)2, S = M
8
Fb
HORIZONTAL SHEAR
Rv = w(1), Fv = 3(Rv)
2
2(b)(d)
DEFLECTION
w
l
b
d
S
M
E
I
F
=
=
=
=
=
=
=
=
=
"Delta"
= 5(w) (1)4 (See Note D)
384 (E) (I)
uniform load per length in inches (See Note A)
length of beam between supporting members in inches
width of rectangular member (actual not nominal) in inches
depth of rectangular member (actual not nominal) in inches
section modulus of lumber (See Note B)
bending moment in inch-pounds
modulus of elasticity of lumber (See Note C) in psi
moment of inertia (See Note B) in (inches)4
allowable unit stress for extreme fiber (See Note C) in psi
2009-21-54
21.22(3)
Fv = allowable unit horizontal shear (See Note C) in psi
Rv = vertical reaction in pounds
= deflection in inches
NOTE A - the uniform load per inch on a beam is calculated from the live loads (LL) and
dead loads (DL) in pounds per square foot (s. Comm 21.02) and length in inches of
supported joists (J). The formula is: w = (DL + LL) (J) / 144
If more than one level is supported by beam or header, add the loads contributed by each
ceiling, floor, and roof system supported to obtain the total uniform load per length on the
beam. (See following diagram.)
NOTE B - The National Design Specification for Wood Construction, Appendix M gives
the value for (S) and (I) for structural lumber. If built up beams and headers are used, the
(S) and (I) for each member can be added together if of the same depth for rectangular
members:
S = (b) (d)2 & I = (b) (d)3
6
12
NOTE C - Fb, Fv and E for various wood species can be obtained from Table 4A in the
Design Value for Wood Construction Supplement to the National Design Specification for
Wood Construction. The values for Fb, Fv & E (allowable) for the wood species must
exceed the calculated fb, fv & E values (actual).
NOTE D - Deflection "Delta" should be limited to (l)/240 to reduce plaster cracking,
objectionable springiness, and stresses on mechanical systems.
Tributary Areas
Supported joist length equals ½
the sum of the joist plus ½ the
required bearing area called for
in the code or truss spans on
both sides of beam or header
2009-21-55
When the beam or header
supports more than one
structural system, the loads
of each system are added.
The following table may be used to size beams or headers. Table A provides the actual
loads per inch on the member for various loading situations.
TABLE A
Designed to give load (w) on a beam or header for various roof, ceiling and
floor systems in pounds per lineal inch. Includes dead and live loads. If multiple loads are
supported by the beam or header, then add the loads together from the applicable columns.
Supported
(w)
(w)
(w)
Member
(w)**
(w)**
Ceiling
Ceiling
Ceiling
(w)
Length
Roof
Roof
Truss No
Joist No
Joist With Floor:
in Feet*
Zone 1
Zone 2
Storage
Storage
Storage
Per System
4
15
13
3
7
10
17
5
19
15
4
9
13
21
6
22
18
5
10
15
25
7
26
21
6
12
18
30
8
31
25
7
14
21
35
9
34
27
8
16
24
39
10
38
30
9
18
26
43
11
41
34
10
19
29
47
12
44
37
11
21
31
51
13
49
40
12
23
33
56
14
53
42
13
24
37
60
15
56
45
14
26
39
64
16
60
48
15
28
42
69
17
64
51
16
29
44
73
18
66
53
17
31
46
76
*See previous page for diagrams. Note that you may need to use different lines of
this table for a beam or header that supports multiple systems of different
supported member length.
**When there is a roof overhang, its length must be added to the supported
member length.
BEAM OR HEADER ACTUAL LOAD = ROOF (w) + CEILING (w) + FLOOR
(w)
Bearing of floor systems beams & girders [per Comm 21.22(4)(a)2.] or engineered wood
products [per Comm 21.22(4)(b)] should be considered to have the load path [from
Comm 21.02(1) requirement] followed beyond just the bearing point sizing for adequate
load transfer, thus such beams may require additional wall studs directly below them all
the way to the foundation below. If such supports have a header in them, typically
separate structural analysis must be provided to properly size this header and those
supporting jamb columns.
21.22(4) Floor Joist Tails
2009-21-56
21.22(6)
Question:
Answer:
Question:
Answer:
Member
Size
2x6
2x8
2x10
2x12
Why can't the tail ends of joists overlap by more than the depth of a floor
joist?
The reason for the requirement is to prevent potential subfloor uplift from
the tail end reaction to the deflection of the joist span. This could be more
of a problem at the center beam of a house in which the clear span roof
trusses are used and there is no bearing wall resting on the floor joist tail
ends.
Can wood shims be used under a steel beam or under a steel column for
minor dimensional adjustments? What about pressure treated lumber?
Maybe, but not likely, since the shim material used would need a
compressive strength equal to or greater than the loads imposed by the
typically highly loaded steel members. If structural calculations are lacking
on this point, then steel shims would be required.
Holes & Notches in Sawn Joists and Rafters (D = Actual Member Depth)
Maximum Hole Diameter Maximum Edge-Hole Diameter or
Maximum End
or Notch Length = D/3
Notch Depth (except at ends) = D/6 Notch = D/4
1-3/4"
7/8"
1-3/8"
2-3/8"
1-1/4"
1-7/8"
3"
1-1/2"
2-3/8"
3-3/4"
1-7/8"
2-7/8'
Max. length
= D/3
D = Actual Member Depth
Max Depth =
D/6
Max. D/4
at ends
Max
D/3
Min. of 2" separation or
larger hole diameter
Sloped
notches
recommended
Min. 2"
No notching in middle 1/3 of span
2009-21-57
Max. length
= D/3
D
21.22(6)
21.22(6) Lookout Joist Cantilevers
21.22(6)(b) - 2' Overhang
of Main Joists
21.22(6)(c) - 2' Overhang
of Lookout Joists
Roof Beam
or Wall
Header
R<J+2'
R<X
E<2'
Metal Joist
Hanger
Floor
Beam
Doubled
Main Joist
X<2'
Main
Y>X
Joist
Lookout Joist
Doubled
Main Joists
Y>2X
X<2'
J
21.22(3) Beam Lateral Restraint
Deeper than 11.25” wood beams at supporting columns shall be provided with lateral
restraint by means of a saddle or other approved connection. A saddle supports the beam
on the bottom, but also allows through-connection of fasteners into the side of the beam.
21.22(6) Deck Cantilevers
2009-21-58
21.24 (4)
Question:
Answer:
This section allows a 2-foot cantilever that supports the wall and roof above
without the need for calculations. Again, without project specific calculations
being required, how far may a deck be cantilevered when it only supports its
own floor load?
In the case of the code allowed 2-foot cantilever, the floor assembly is
supporting its own known uniform floor load and a point load from the roof
system of an unknown span. Therefore it is very conservative. In the
proposed case of a cantilevered deck supporting only its own floor load, the
loads are all known, therefore a more liberal treatment is possible. So
theoretically, the cantilever could be one-half of the simple beam span. This
would also parallel the requirement of s. Comm 21.22(6)(b) that the cantilever
be anchored back two times the overhang. However, the owner may be
unhappy with the deflection at the end of the deck, since for a given span, the
deflection for a cantilever is about ten times that of a simple span.
Besides the above analysis, the designer should evaluate the need for any
uplift restraint on the backspan at the most critical loading where the
cantilever has full live plus dead loads, while the backspan is under dead load
only.
The deflection, non-uniform loading and uplift concerns, should be addressed
by the designer. Also, the designer must confirm the assumption that the
backspan joist is adequate for the simple span loading case before using the
above formula to determine the cantilever length.
21.22(7) Joists Bearing Over Window Openings
In the absence of a wall header, the requirements of Comm 21.22(7) apply to floor joists
that end above a window or other wall opening. This is typically the case for basement
windows. Therefore, either framing anchors or a ledge strip, including a sill plate, is
required for proper bearing for any joists over 8 feet long.
21.24 Exterior Covering
Question: Must the siding or finished surface material be in place before insulation can
be installed?
Answer:
No, so long as it is “protected” from the elements which could cause
excessive moisture in the finished walls. This “protection” could be any of
the materials above. You should note that most building paper is listed by
the manufacturer to not be directly exposed to weathering (sunlight & rain)
for extended periods, unless it will be replaced before finish siding materials
are installed over it. Also note that this requirement does include gable &
dormer walls, not just walls which are part of the building thermal envelope
[for which building paper may be used to meet infiltration resistance
requirements of Comm 22].
21.24 (4) Water Resistive Barrier (Drainage Plane)
2009-21-59
21.25(3)
Specific standards for water-resistive barrier materials are now found in the code. These
include material compatibility, performance and application requirements, as well as
minimum protection or flashing of most penetrations of the barrier materials.
21.25 Wood Frame Walls
Question: Based on Table 21.25-A, if I have an exterior gable end-wall with a cathedral
ceiling that is greater than the stud height allowed, do I have any options other
than cutting the studs and installing double top plates?
Answer:
Yes, if the allowable height is exceeded, there are three ways of handling this
condition:
1. If the maximum allowed stud length is 10 feet, continuous 2” full-depth
solid wood blocking could be installed throughout the wall between all
studs at the mid-point of the wall height (but in no case exceeding the 10’
limitation).
2. The second option would be to install solid wood sheathing material on
both the exterior and the interior of this stud wall, covering the entire wall
area (under the interior wall finish).
3. Use engineered lumber
Table 21.25-A allows some non-bearing stud walls with heights exceeding the 10’
maximum that was previously allowed without structural analysis. Per the table footnote,
these non-bearing wall heights are for interior walls only.
21.25(3) Wall Opening Framing
Question
What are some examples of acceptable headers for openings in exterior
walls?
Answer
Header sizes shown in Tables 21.25-B, C, & D for dimension lumber are
acceptable typical headers. For headers exceeding the spans given in Tables
21.25-B, C, and D, see s. 21.22(3) of this commentary for design
information.
Comm 21.25(3)(b) prescribes header support minimum standards. The following
diagrams are intended to clarify the text. Remember that the “span” is the clear span plus
½ the required bearing area of the header at each end.
Header Supports
framing anchor
shoulder stud
common stud
2009-21-60
21.25(6)
Either option for up to a 3-foot span.
Single shoulder stud
From 3- to 6-foot span
Double shoulder stud
Greater than 6-foot span
21.25(6) Telescoping Columns
Question: Are telescoping or expandable jacks or columns allowed in the construction
of one- and two-family dwellings?
Answer:
The use of the telescoping jack post (adjustable height columns) to support
beams is not prohibited by the UDC provided they are capable of supporting
the imposed loading per Comm 21.25(6)(c)1. The installation shall comply
with the manufacturer's installation instructions for spacing, load capacity,
maximum height adjustment, beam or footing anchorage and proper method
to secure the adjustment device while in service. The adjustable jack should
be stamped or bear a sticker which indicates its allowable load. They must
be secured at both the top and bottom of the column the same as any other
column. Caution should be used on the limitations of screw adjustment
permitted for a particular load and even which end is up must follow listing.
Question:
Answer:
What are foundation cripple walls?
Rules under Comm 21.25(7) were added in 2009 to address the hinge-action
caused by placing a wood-framed wall above a partial-height foundation
wall of typically masonry or concrete exterior of ground floor or walk-out
basement.
2009-21-61
21.25(8)
Floor Joists
Siding & building
paper over structural
wood sheathing
Cripple wall (shown shaded)
Foundation wall
21.25(8) & (9) Wall Bracing
Since the first edition of the Uniform Dwelling Code (UDC) that became effective June
1, 1980, the UDC has required construction that resists lateral wind loads of 20 pounds
per square foot of external wall area. This change in the rules on wall bracing incorporate
more design and construction specifications in an effort to assure the long-standing
performance requirement is met. The additional specifications are based on those
contained in the 2006 edition and 2007 supplement of the International Residential Code,
developed by the International Code Council.
2009-21-62
21.25(8)
There are a couple of terms a person will need to become familiar with whether using the
interminante bracing method of Comm 21.25 (8), alternate bracing method of Comm
21.25 (9)(b) or the continuous sheathing method of 21.25 (9) (c):
Braced Wall Line: A braced wall line (BWL) consists of wall segments that are
off-set no more than 4’ from the BWL. Within that braced wall line
are braced wall panel(s) that provide resistance to wind loads. The
spacing of a BWL shall not exceed 35’, or 50’ meeting certain
additional conditions. [See Comm 21.25 (8)(e) and Fig. 21.25-A]
Braced Wall Panel: A braced wall panel (BWP) is an individual bracing
component that is installed within a braced wall line. Examples of
types of BWP are let-in bracing, wood boards, wood structural
panels, structural fiberboard, and gypsum board [See Comm 21.25
(8) (b)]. The BWP, unless otherwise specified in the code, shall
begin no more thatn 12.5 feet from each end and shall be located
every 25 feet on center.
Question:
Answer:
Question:
Answer:
Question:
Answer:
May the latest wall bracing provisions, s. R602.10, set forth in the 2009
edition of the International Residental Code (IRC) be used to meet the wall
bracing provisions this code?
Yes. When using the UDC provision or the 2009 IRC provison, whichever
one is used, it shall be used in its entirety. The provison of each may not be
mixed and matched. Once the 2009 IRC wall bracing provions are available
for reprint, they will be reprinted in the UDC appendix. For the time being
the 2009 IRC can be viewed on the ICC website www.iccsafe.org. Select
the ICC Store tab and click on the dropdown box eCodes.
Comm. 21.25(8)(b)6. requires gypsum boards used as braced wall panels to
be fastened at panel edges by nails specified in the fastener table in the
appendix spaced no more than 7 inches on center while the fastener table
itself specifies a spacing of 4 in. on the edges and 8 inches at intermediate
supports. Which one controls?
The fastener spacing specified in the table is for gypsum sheathing used on
the exterior of the building. Gypsum boards used as bracing panels on
interior walls may have fasteners spaced 7 inches on center.
May four (4) foot long braced wall panels be used as a substitute where
wood and metal let-in bracing is permitted by Table 21.25-G?
Yes. Let-in bracing may not, though, be used as a substitute for braced wall
panels where required by Table 21.25-G.
2009-21-63
21.25(8)
Question:
Answer:
May I use wood structural panels less than 4 ft. in length in a braced wall
line and comply with the intermittent braced wall provisions of the Comm
21.25 (8)?
Yes. As long as the length used meets Table 21.25-G and the “effective”
length used to determine panel bracing percentage is as specified in the
same. [See example calculation and figure below.]
Example: [Effective braced wall panel length = 36” X 2 = 72”] > [0.16 X 35’ or
67.2” from Table 21.25-H] OK.
42”
42”
9’
Supporting
roof only
35’
Question:
Answer:
Question:
Answer:
Question:
Answer:
Section Comm 21.25(8) (e)2. refers to Table 21.25-G when determining the
“adjusted” percent wall bracing. Is that the right table to reference?
No. The table that should be referenced is Table 21.25-H.
What is the maximum wall height permitted when using the “prescriptive”
wall bracing methods of Comm 21.25 (8) & (9)?
12 feet. See Table 21.25-H, footnote 4, and Table 2.25-I where 12 foot
height walls would be permitted. Code compliance for those walls greater
that those heights specified in these sections will need to be designed and
constructed in accordance with accepted engineering practice.
If my braced wall line spacing is more than 35 feet and is less than, or equal
to, 50 ft. may I use wood or metal let-in bracing in those braced wall lines
that are spaced more than 35 ft. apart?
No. Braced wall lines that are more than 35 ft. apart must have the required
length of braced wall panels specified in Table 21.25-H increased by a
factor of the braced wall line spacing divided by 35. Let-in bracing does not
provide an equivalent amount of wind resistance as compared to the added
sheathing required by this section.
2009-21-64
21.25(8)
Braced wall lines spaced more than 35 ft. apart and let-in bracing
Braced
wall
line
Braced
wall
line
50’
Example: 50’/35’ times
percent value from Table
21.25-H = Adjusted min.
braced wall panel percentage.
Braced wall
panels. Let-in
Bracing is Not
Permitted!
Question:
Answer:
Question:
Answer:
The last sentence in Footnote 5 of Table 21.25-H refers to Table 21.25-J. Is
that the right table reference?
No. The table that should be referenced is Table 21.25-K.
If I have a walk-out basement with a full-height wood frame exterior wall on
one side and the rest of the floor level is below grade, do I need an interior
braced wall line if the length of the wall is greater than 35 feet?
No. The braced wall lines spaced at 35 feet are there to provide resistance
to wind loads. Since the wall is braced at the top by the floor system and the
load is transferred through the floor system to the below grade foundation
wall on the opposite side of the ground floor, the lateral resistance to wind
for the wall is provided. The exposed exterior walls, though, would still
have to meet the wall bracing provisions of Comm 21.25 (8) and/or (9).
2009-21-65
21.25(8)
Lower Grade
- Walkout Basement
50’
Wood frame
wall
Ground
floor
Interior braced
wall line not
required
Upper Grade
Question:
Answer:
Concrete
foundation wall
Must a braced wall line with 4’offsets be in line with an actual building
wall line as shown in Fig. 21.25-C?
No. A braced wall line can be located within actual building wall lines as
long as the physical building wall lines are not offset by more than 4 ft.
(See Fig. below). This method of determining the braced wall line is
consistent with the wall bracing provisions of the 2009 International
Residential Code which is an approved engineering analysis as set forth in
Comm. 21.25(8)(1), footnote.
4 ft. Max.
Braced wall line
8 ft. total
max.
4 ft. Max.
Braced wall line with 4 ft. offsets
2009-21-66
21.25(8)
Question:
Answer:
If I fully sheath my homes have I automatically satisfied the requirements of
the wall bracing provisions of the UDC?
No. The plans will have to clearly show the location and design detail of the
braced wall panels, the location and details of required interior braced wall
lines and their panel(s), location and details of required corner and 2- foot
end-wall return(s), location and details of required tie-downs, etc. as
specified in Comm 21.15 (8) and (9)(c).
Even if the home is fully sheathed, it is suggested that the builder/designer
first determine if the intermittent braced wall panel method of Comm. 21.25
(8) can be used. This would eliminate the need for the 2-foot end- wall
returns, special corner construction, the possible need for tie-downs, etc. If
you can not comply with the intermittent wall bracing provisions, then take
a look at using the continuously sheathed wall bracing method. If there are
still wall segments that are too narrow when applying the continuously
sheathed method, a person can look at using Fig. 21.25-K, then 21.25-E and,
finally, going to a proprietary wall bracing system.
Question:
Answer:
Question:
Answer:
Question:
Answer:
Question:
Answer:
Question:
If I fully sheath my homes, do all of my panels have to have blocking at all
the joints?
No. Only the required braced wall panels need to be blocked. This would
also exclude the 2-foot end-wall returns. [See Comm. 21.25 (8)(h) 1. and
2.]
If I use the continuously sheathed method of Comm 21.25 (9) (c) do also
need to space braced wall panels no more than 25 on center?
Yes. Comm 21.25 (8) (d) is the general section that also applies to the
provisions of Comm 21.25 (9) (c). Comm 21.25 (9) (c) permits you to use
narrower wall bracing panels in a braced wall line.
When determining the braced wall panel length requirements using Table
21.25-J may I use the 4:1 ration for full-height sheathed wall segments on
either side of garage openings?
Yes. Footnote 2 of the table permits you to do this. This exception, though,
is limited to a garage that supports a roof only. It may not have occupied
space above it such as a bonus room, attic storage, second floor.
Fig. 21.25-G, (c) refers of sub. (9) (c) 6. for garage door corner details. Is
that the right section to reference?
No. The section that should be referenced is sub. (9) (c) 5.
Fig. 21.25-G specifies that 8d nails be used while the fastener table in the
appendix permits 6d nails for wall bracing panels with a thickness of 5/16”
2009-21-67
21.25(8)
Answer:
to ½”. Is the 6d nail permitted in these corners when use sheathing in that
thickness range?
No. The most restrictive applies. 8d nails shall provided in those areas
shown in figure 21.25-G.
Wall Bracing Examples:
Building #1
One-Story
Front Elevation
2009-21-68
21.25(8)
Continuously- sheathed per s. Comm 21.25(9)(c)5., Fig. 21.25-K,
Four Feet of Wood Structural Panel Sheathing or Diagonal
Four Feet of Gypsum Wallboard Applied to Both Sides of Wall or Diagonal Bracing.
A
B
C
5
4
3
2
1
Building #1
One-Story
First Floor
2009-21-69
D
E
21.25(8)
Steps used to determine wall bracing for Bldg. # 1
[Note: The plans and selected bracing solutions were presented at the winter 2009
building inspector association sponsored UDC training sessions. Alternative wall
bracing solutions have been provided in this training module.]
1. Find braced wall lines in exterior walls using north-south and east-west grid line
pattern. Braced wall lines may include walls that are offset no more than 4 ft. [Comm
21.25(8)(e)]
2. Check the width of the building to determine whether or not an interior braced wall
line is needed. (Spaced no more than 35 ft. apart, or up to 50 ft., with conditions.)
[Comm 21.25(8)(e)1. & 2.]
3. Grid Line # 1
• First check to see if you can comply with the wall bracing provisions of
Comm 21.25 (8) for 4 ft. wide panels or let-in bracing. This wall does not
have the 4 ft. wide space available on either side of the garage door.
• An option, as identified on the plan, would be to use the continuously
sheathed method of Comm 21.29(9)(c), Fig. 21.25-K with 2’ returns.
o If the garage wall height is 9 ft., this design with the 3” nailing pattern
and sheathing overlapping the header permits you to have sheathing on
the sides of the garage door opening of 18” min. OK
o The percent of braced wall panels provided shall be checked for
conformance with Comm 21.25(9)(c)5.c., Table 21.25-H. The length
required for this wall line would be 23’ X 0.16 = 3.68 ft. OK.
o Be reminded that the corners at the end of this braced wall line will
have to be constructed in accordance with Fig 21.25-G.
• Another option to consider is Comm 21.25(8)(c)2.c., Table 21.25-G. If the
wall height of the garage is 9 ft., braced wall panels could be reduced from
48” to 42” in width. If 42” width is provided, then the continuously sheathed
method with 3” nailing pattern and 2 foot returns would not be needed. This
would still meet the percentage requirements of Tables 21.25-G and 21.25-H.
[23 ft. X 0.16 = 3.68 ft. The effective length of 36 in. from Table 21.25-G X
2 sides = 72” or 6 ft. > 3.68 ft. OK]
4. Grid Line # 2 - Provide 4 ft. wide panels or let-in bracing within 12.5 feet of each end.
5. Grid Line # 3 - This grid line contains interior and exterior wall segments that are
offset no more than 4 ft. from the braced wall line. Since this is considered one braced
wall line, braced wall panels or let-in bracing must only be provided within 12.5 ft. of the
ends and spaced no more than 25 ft. on center. As this is no more than 35 ft. from grid
line #1 and Grid line #4 this satisfies the maximum 35 ft. braced wall line spacing
requirements. Note: Grid line # 4 was used for this spacing determination instead of grid
line #5 as it is that exterior wall that has the majority of the braced wall panels to resist
the wind loads.
2009-21-70
21.25(8)
6. Grid Line # 4 - Provide 4 ft. wide panels or let-in bracing within 12.5 ft. of each end
and a max. of 25 ft. on-center.
7. Grid Line # 5 - Provide 4 ft. wide panels or let-in bracing within 12.5 feet of each end.
The plan shows 2 - 4 ft. wide panels. The code may be met by using just one panel in the
center of the braced wall line as this would be within 12.5 ft. of each end. The single
panel would also meet the percentage requirements of Table 21.25-H. [15 ft. X 0.16 =
2.4 ft. < 4 ft. provided.]
8. Grid Line A
• Provide 4 ft. wide panels within 12.5 ft. of each end and a max. of 25 ft. oncenter.
• Note: The plans show that let-in/diagonal bracing can be used in this braced
wall line. After further review and consideration it has been determined that
let-in bracing can not be used because this is a braced wall line that exceeds
the 35 ft. braced wall line spacing requirement (grid lines A and D) resulting
in a need for a check of an added amount of wall bracing required by Comm
21.25(8)(c)2.
• Determine percent wall bracing required. Since the distance between braced
walls lines A and D is 46 ft. the required percentage would be (46 ft./35 ft. X
0.16) X 64 ft. wall length = 13.5 ft. < 16 ft. provided. OK.
9. Grid Line B - Provide a 4 ft. wide panel within 12.5 ft. of each end.
10. Grid Line C - Provide 4 ft. wide panels within 12.5 ft. of each end. A single panel
centered in the braced wall line would meet this requirement. Note, though, that a 2 ft.
return may be required at the overhead garage door and the 4 ft. panel at the end would
serve a dual purpose.
11. Grid Line D
• This grid line contains interior and exterior wall segments that are offset no
more that 4 ft. from the braced wall line. Since this is considered one braced
wall line, braced wall panels or let-in bracing must only be provided within
12.5 ft. of the ends and spaced no more than 25 ft. on center.
• Note: The plans show that let-in/diagonal bracing can be used in this braced
wall line. After further review and consideration it has been determined that
let-in bracing can not be used because this is a braced wall line that exceeds
the 35 ft. braced wall line spacing requirement (grid lines A and D) resulting
in a need for a check of an added amount of wall bracing required by Comm
21.25(8)(c)2.
• Determine percent wall bracing required. Since the distance between braced
walls lines A and D is 46 ft. the required percentage would be (46 ft./35 ft. X
0.16) X 47 ft. wall length = 9.9 ft. < 16 ft. provided. OK.
12. Grid Line E - Provide 4 ft. wide panels or let-in bracing within 12.5 feet of each end
and a max. of 25 ft. on-center.
2009-21-71
21.25(8)
Building #2
Two-Story
Front Elevation
2009-21-72
21.25(8)
Continuously- sheathed per s. Comm 21.25(9)(c)5., Fig. 21.25-K, W/2
Four Feet of Wood Structural Panel Sheathing or Diagonal Bracing
Continuously- sheathed per s. Comm 21.25(9)(c) 2.&3., W/2 foot
Four Feet of Gypsum Wallboard Applied to Both Sides of Wall or Diagonal
A
B
C
6
5
4
3
2
1
Building #2
Two-Story
First Floor
2009-21-73
D
E
F
21.25(8)
Steps used to determine wall bracing for Bldg. # 2
[Note: The plans and selected bracing solutions were presented at the winter 2009
building inspector association sponsored UDC training sessions. Alternative wall
bracing solutions have been provided in this training module.]
1. Find braced wall lines in exterior walls using north-south and east-west grid line
pattern. Braced wall lines may include walls that are offset no more than 4 ft. [Comm
21.25(8)(e)]
2. Check the width of the building to determine whether or not an interior braced wall
line is needed. (Spaced no more than 35 ft. apart or up to 50 ft. with conditions.) [Comm
21.25(8)(e)1. & 2.]
Steps used to determine wall bracing for Bldg. # 2, First Floor
3. Grid Line # 1
• First check to see if you can comply with the wall bracing provisions of
Comm 21.25 (8) –- 4 ft. wide panels or let-in bracing. This wall does not
have the 4 ft. wide space available on either side of the garage door.
• An option, as identified on the plan, would be to use the continuously
sheathed method of Comm 21.29(9)(c), Fig. 21.25-K with 2’ returns.
o If the garage wall height is 9 ft., this design with the 3” nailing pattern
and sheathing overlapping the header permits you to have sheathing on
the sides of the garage door opening of 18” min. OK
o The percent of braced wall panels provided shall be checked for
conformance with Comm 21.25(9)(c)5.c., Table 21.25-H. The length
required for this wall line would be 23’ X 0.16 = 3.68 ft. OK.
o Be reminded that the corners at the end of this braced wall line will
have to be constructed in accordance with Fig 21.25-G.
• Another option to consider is Comm 21.25(8)(c)2.c., Table 21.25-G. If the
wall height of the garage is 9 ft., braced wall panels could be reduced from
48” to 42” in width. If 42” width is provided, then the continuously sheathed
method with 3” nailing pattern and 2 foot returns would not be needed. This
would still meet the percentage requirements of Tables 21.25-G and 21.25-H.
[23 ft. X 0.16 = 3.68 ft. The effective length of 36 in. from Table 21.25-G X
2 sides = 72” or 6 ft. > 3.68 ft. OK]
4. Grid Line # 2 - Provide a 4 ft. wide panel or let-in bracing within 12.5 feet of each
end.
5. Grid Line # 3.
• This wall does not have the 4 ft. wide space available on either side of the
entrance door. The continuously sheathed method, as identified on the plan,
will need to be used. In accordance with Table 21.25-J, the braced wall
segments at the ends of this braced wall line will have to be at least 32 in.
2009-21-74
21.25(8)
•
wide and have a return at the ends of at least 2’. In addition the corners will
have to be constructed in accordance with Fig. 21.25-G.
An option, if the builder can not meet the 32” min. braced wall panel length
requirement, would be to use the continuously sheathed method of Comm
21.29(9)(c), Fig. 21.25-K with 2’ returns. The additional nailing and
overlapping of sheathing over a header would permit a braced wall panel
width of 16” in an 8 ft. high wall.
6. Grid Line # 4 - Provide a 4 ft. wide panel or let-in bracing within 12.5 feet of each
end.
7. Grid Line # 5 - Provide 4 ft. wide panels or let-in bracing within 12.5 ft. of each end
and a max. of 25 ft. on-center. The plan shows 2 - 4 ft. wide panels. The code may be
met by using just one panel in the center of the braced wall line as this would be within
12.5 ft. of each end. The single panel would also meet the percentage requirements of H. [14 ft. X 0.16 = 2.24 ft. < 4 ft. provided.]
8. Grid Line # 6
• This grid line contains exterior wall segments that are offset no more that 4 ft.
from the braced wall line. Since this is considered one braced wall line, braced
wall panels or let-in bracing must only be provided within 12.5 ft. of the ends and
spaced no more than 25 ft. on center.
• Determine percent wall bracing required per Table 21.25-H.: 40 ft. wall length X
0.16 = 6.4 ft. < 12 ft. provided. OK.
9. Grid Line A
• This wall does not have the 4 ft. wide space available between the fireplace and
the windows, if all were provided in this braced wall line. The continuously
sheathed method was identified as an option on the plan. In accordance with
Table 21.25-J, this would mean that the braced wall segments at the ends of this
braced wall line will have to be at least 24 in. wide if the wall is 8 ft. in height and
the windows do not take up more than 67% of the wall height.
• If this width can not be met, the fireplace will have to go if the windows are
provided and, if the fireplace is provided, the windows must go. Also, if the
fireplace or windows are not provided there may be enough space in the braced
wall line to get a 4 ft. braced wall panel in and thus eliminating the 2 ft. returns,
and specially constructed corners per Fig. 21.25-G.
• Another option may be use Comm 21.25(9)(c)5., Fig. 21.25-K with returns.
10. Grid Line B - Provide a 4 ft. wide panel within 12.5 ft. of each end.
11. Grid Line C - Provide 4 ft. wide panels within 12.5 ft. of each end. A single panel
centered in the braced wall line would meet this requirement. Note that, if a 2 ft. return is
required at the overhead garage door, the 4 ft. panel at the end would serve a dual
purpose.
2009-21-75
21.25(8)
12. Grid Line D
• This grid line contains interior and exterior wall segments that are offset no
more that 4 ft. from the braced wall line. Since this is considered one braced
wall line, braced wall panels or let-in bracing must only be provided within
12.5 ft. of the ends and spaced no more than 25 ft. on center.
• Note: The plans show that let-in/diagonal bracing can be used in this braced
wall line. After further review and consideration it has been determined that
let-in bracing can not be used because this is a braced wall line that exceeds
the 35 ft. braced wall line spacing requirement (grid lines A and D) resulting
in a need for a check of an added amount of wall bracing required by Comm
21.25(8)(c)2.
• Determine percent wall bracing required. Since the distance between braced
walls lines A and D is 46 ft. the required percentage would be (46 ft./35 ft. X
0.16) X 47 ft. wall length = 9.9 ft. < 16 ft. provided. OK.
13. Grid Line E - Provide 4 ft. wide panels or let-in bracing within 12.5 feet of each end
and a max. of 25 ft. on-center.
2009-21-76
21.25(8)
Four Feet of Wood Structural Panel Sheathing or Diagonal
A
B
2
1
Building #2
Two-Story
Second Floor
2009-21-77
21.25(8)
Steps used to determine wall bracing for Bldg. # 2, Second Floor
1. Grid Line # 1
• This grid line contains exterior wall segments that are offset no more that 4 ft.
from the braced wall line. Since this is considered one braced wall line,
braced wall panels or let-in bracing must only be provided within 12.5 ft. of
the ends and spaced no more than 25 ft. on center.
• Determine percent wall bracing required per Table 21.25-H.: 40 ft. wall length
X 0.16 = 6.4 ft. < 12 ft. provided. OK.
2. Grid Line # 2
• This grid line contains exterior wall segments that are offset no more that 4 ft.
from the braced wall line. Since this is considered one braced wall line,
braced wall panels or let-in bracing must only be provided within 12.5 ft. of
the ends and spaced no more than 25 ft. on center.
• Determine percent wall bracing required per Table 21.25-H.: 40 ft. wall length
X 0.16 = 6.4 ft. < 12 ft. provided. OK.
3. Grid Line A
• Provide 4 ft. wide panels within 12.5 feet of each end and a max. of 25 ft. oncenter.
• Note: The plans show that let-in/diagonal bracing can be used in this braced
wall line. After further review and consideration it has been determined that
let-in bracing can not be used because this is a braced wall line that exceeds
the 35 ft. braced wall line spacing requirement (grid lines A and D) resulting
in a need for a check of an added amount of wall bracing required by Comm
21.25(8)(c)2.
• Determine percent wall bracing required. Since the distance between braced
walls lines A and D is 40 ft. the required percentage would be (40 ft./35 ft. X
0.16) X 22 ft. wall length = 4.0 ft. < 8 ft. provided. OK.
4. Grid Line B
• Provide 4 ft. wide panels within 12.5 feet of each end and a max. of 25 ft. oncenter.
• Note: The plans show that let-in/diagonal bracing can be used in this braced
wall line. After further review and consideration it has been determined that
let-in bracing can not be used because this is a braced wall line that exceeds
the 35 ft. braced wall line spacing requirement (grid lines A and D) resulting
in a need for a check of an added amount of wall bracing required by Comm
21.25(8)(c)2.
• Determine percent wall bracing required. Since the distance between braced
walls lines A and D is 40 ft. the required percentage would be (40 ft./35 ft. X
0.16) X 30 ft. wall length = 5.5 ft. < 8 ft. provided. OK.
2009-21-78
21.28(6)
Subchapter VIII  Roof and Ceilings
21.27(1)(c) Sloped Roof Snow Loads
This section allows reduction of snow loads on roofs sloped more than 30 degrees. This
means a reduction may be taken on roofs with greater than a 7:12 slope. This reduced
design snow load may be transmitted down through the structure including any headers
or beams. (See table below for examples.)
However, it must be remembered that s. Comm 20.02 also requires a 20 PSF wind load
acting on the vertical roof projection.
Reduced Snow Load for High Slope Roofs = Cs x Design Snow Load
Cs = [1 - (a - 30)]/40
a = angle in degrees
Rise
a
Run
Rise/Run = Slope = tan a
Arctan(slope) = a
Slope
7/12
10/12
12/12
14/12
a Zone 1 PSF
30
40
40
30
45
25
50
20
Zone 2 PSF
30
22.5
18.8
15
21.27(2) Resistance to Horizontal Wall Thrust from Rafters
Sloping roof rafters will push their supporting walls outward unless this force is properly
resisted. Collar ties, which are required in the upper one-third of the rafter, provide some
fixity of in the joining of the upper rafter ends, but do not provide much resistance to
outward wall thrust. Typically the horizontal wall thrust needs to be resisted by wall ties
or ceiling joists or by a ridge beam sized to carry half of the rafter loads.
21.28(6) Reroofing
Question: Can re-roofing be done without removing the existing layers of roofing?
Answer:
The subject of the number of layers of roofing materials that can be placed
now onto an existing roof system is now addressed in the dwelling code
specifically and limited to two [one new layer on top of one existing layer].
However, the design loads of the roof rafter or trusses should not be
exceeded. The span tables in the UDC assume dead loads that will typically
allow a total of two lightweight roof layers. Additionally, the installation of
the roof covering materials would have to be in accordance with the
installation requirements.
2009-21-79
21.29(6)
Subchapter IX Fireplace Requirements
21.29 Masonry Fireplaces
2009-21-80
21.29(6)
\
2009-21-81
21.29(12)
21.29(6) Hearth Extension
Question: How is the hearth extension measured?
Answer:
The hearth or hearth extension is measured from the face of the fireplace
opening and not from the front of the firebox, spark screen, or glass doors.
The face of the fireplace includes any trim materials provided on the front
of the fireplace. Earlier editions of the UDC permitted measurement from
the firebox, but as of the 1989 Edition, the measurement is to be taken from
the face of the fireplace opening.
Fireplace opening
equal to or
greater than 6 ft2
Fireplace
opening less
than 6 ft2
12 in.
Fireplace
facing
20 in.
16 in.
Hearth extension
Fireplace hearth extension requirements
2009-21-82
8 in.
21.30(7)
21.29(12) Framing Around Fireplaces
Question: This section refers to 21.30(9) which requires 2-inch clearances from
fireplace masonry to combustibles. In some cases, the block and brick may
cover an entire wall. In such a case, is it necessary to maintain the 2-inch
clearance from the entire wall?
Answer:
Because of the expected heat dissipation in such an installation, the
department will accept the ends of the beams and headers to be placed
without a 2-inch clearance if at least 12 inches of solid masonry is also
provided between the member and the firebox or chimney flue. If the wood
structural member is supported in the masonry, it must be fire cut or a selfreleasing device must be used as required by s. Comm 21.26(9)(c).
Note the requirement for clearances to a fireplace applies only to framing.
Other combustible elements such as mantles, trim, and flooring would need
to comply with the s. Comm 21.29(11), as well as the hearth requirements
of s. Comm 21.29(6).
21.30(7) Flue Liners
Question: If a stainless steel flue liner is used, what gauge stainless steel may be used to
line a masonry chimney?
Answer:
Stainless steel of 22 gauge or thicker is acceptable.
21.30(9) Fireblocking of Chimneys
Question: The Uniform Dwelling Code requires 2 inches of clearance between
combustible headers, beams, rafters, joists and studs and the outside face of
a interior chimney (1 inch for an exterior chimney). Does subs. Comm
21.085(1) on fire separation also apply where this rule states "holes around
ducts and pipes shall also be fireblocked"?
Answer:
Yes. It is the intent for Comm 21.085(1) and 21.30(9)(a) to apply to the 2inch or 1-inch clearance between the chimney and the structural members.
Noncombustible fire blocking material must be used. In addition, insulation
is not acceptable for fire blocking metallic chimneys or vents per Comm
21.30(9)(b)&(c) as this would cause “hot spots” to occur and most likely
harm them and/or void the manufacturer’s testing.
2009-21-83
21.32
2 FT MINIMUM
10 FT
3 FT
MINIMUM
MINIMUM
Building Code Dimensions Requirements
FLUE
LINER
SEALANT
2 IN. MINIMUM
FORM
WORK
BOND BREAK
2 1/2 IN MIN.
OVERHANG
CAST-IN-PLACE
DETAILS
1/2 IN. MINIMUM AIRSPACE
BETWEEN LINER AND MASONRY
PREFABRICATED
DETAILS
CHIMNEY CAP DETAIL
FLUE SUPPORT
PARGING
TYPICAL TIE
HIGH FORM
DAMPER
SMOKE SHELF
SHELF ANGLE
NONCOMBUSTIBLE
MATERIAL
COMBUSTION
CHAMBER
COMBUSTION CHAMBER
WALL
1/2 IN. MIN. AIRSPACE
2009-21-84
21.32
21.32 Factory-Built Fireplaces
The department conducted an investigation regarding factory-built fireplace installations.
As a result of the investigation, it was felt special consideration should be given to two
important installation requirements that are especially important to proper operation of
such fireplaces.
Per s. Comm 21.32, factory-built fireplaces and their specified chimneys shall be tested
and listed by a nationally recognized testing laboratory. Furthermore, the fireplace
assembly and chimney shall be erected and maintained in accordance with the conditions
of the listing. Currently acceptable testing and listing laboratories for this and other
purposes are listed below. Not all will test all classes of appliances.
- Underwriter's Laboratories (UL)
- Electrical Testing Labs of New York (ETL-NY)
- Energy Testing Labs of Maine (ETL-MAINE)
- Canadian Standards Association (CSA)
- Product Fabrication Service (PFS)
- Warnock Hersey
Specific emphasis should be placed on inspection of the construction gap between the
front of the fireplace unit and the finish material or facia. Most, if not all, manufacturers
require the gap be filled with noncombustible caulk or equivalent. The fear, although not
specifically verified by our investigation, is that hot gases or sparks can migrate out of the
fire box through such an opening and eventually cause ignition of the unprotected
combustibles behind the facia. Improper drafting could increase the likelihood of such an
occurrence.
Typically the crack between the fireplace and hearth must also be properly sealed against
entry of sparks and coals if there is combustible flooring below.
The use of any add-on items should be closely checked as to whether they are listed for
that particular fireplace. Be especially suspicious of retrofitted stoves or fireplace inserts
which can cause severe problems if the fireplace was not designed for them.
Also, fireplace doors should be checked to verify that they are of a type made by the
fireplace manufacturer and approved for installation on that model. Oversize doors could
restrict combustion air supply, block air circulation vents or slots that cool the unit or
even deflect heat or hot gases laterally into the construction gap between the front of the
unit and the surrounding facia as described above.
In conclusion, all manufacturer's installation requirements should be followed. An
inspector is entitled to request a copy of manufacturer's installation instructions, per
s. Comm 20.09(4)(b), in order to conduct proper inspections.
Question:
Many pre-manufactured fireplace installation instructions require a
noncombustible insulating material be placed between the hearth extension
2009-21-85
21.32
Answer:
finish material and the combustible floor. Is this noncombustible insulating
board required by the UDC?
Indirectly, yes. Section Comm 21.32(1) requires the entire fireplace
installation be installed per the manufacturer's listing. The hearth extension
design is part of the listing. The insulating board specifications vary between
fireplace manufacturers. For example, some “Preway” Models requires
either of two of its products, “Preway” HE 36-1 or HE 3624. An alternative
material should be equal to 3/4-inch thick noncombustible insulating material
with a thermal conductivity of k = 0.55 (Btu)(in)/(hr)(sqft)(oF). As an
alternative to k-value, a 3/4-inch noncombustible material with a thermal
conductance C = .73 or thermal resistance R = 1.36 is acceptable. Besides
the Preway products mentioned, other trade name products such as "Celotex
CV 230", "Micore" and "Spec 300" boards may also be acceptable (check kvalues).
21.32 Gas Fireplaces
Question: Are gas-only fireplaces required to have a hearth extension per the UDC?
Answer:
No. Gas-only fireplaces are covered by s. Comm 23.04 as a gas appliance
and need to be installed per their listing, which typically may not require a
hearth extension.
21.32 Factory-Built Fireplace Chimneys
Question: Does the requirement of s. 23.045(3)(a)1., that factory-built chimneys be
tested to 2,100oF ("high-temperature" rated) if connected to a solid-fuel
appliance, apply to a factory-built fireplace?
Answer:
No. Section 23.045 applies to solid-fuel appliances other than those covered
by other sections of the code such as masonry and factory-built fireplaces
(ss. Comm 21.29 through 21.32). The proper chimney for a factory-built
fireplace is the one it was tested and listed with and is normally shipped with
the unit. It is possible that such listed fireplace assemblies will have a lower
temperature chimney.
Subchapter X - Construction in Floodplains
This is the only place in the UDC that licensed architect or professional engineer can be
required by code language to verify code is met [all other code compliance calculations
may be accepted from non-licensed persons, but for this it must be from licensed
persons].
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21.40
Subchapter XI - Installation of Manufactured Homes
21.40 Manufactured Homes
Since April 1, 2007 manufactured homes [formerly know as mobile homes or HUD
homes] are required by UDC to meet certain installation standards. Please see
information on the Safety & Buildings website under the Manufactured Home program
for more complete information on the regulation and installation of these homes. Links
from that program page currently include minimum acceptable foundation design, with
limitations and also include a draft version of the federal installation standards from
HUD.
http://www.commerce.state.wi.us/SB/SB-ManufacturedMobileHomesProgram.html
The manufacture date of the home is key to the installation standards that it must follow,
as well as the edition of the electrical code and other codes governing the interior of that
home. However any site-constructed additions or foundations to such homes are covered
by the current UDC, as noted in Comm 20.04(5)(b) that would require the new home
placed on an existing foundation to have that foundation need to be UDC inspected and
brought up to current UDC code minimums.
For older manufactured homes being installed on a new site and foundation, Comm
21.40(2) gives two options. First they can install it per the requirements in effect at the
time the manufactured home was produced - this is per the manufacturer’s installation
instructions that is similar to the post April 1, 2007 homes method. The second option is
to install on piers per the 17 minimum requirements of Comm 21.40(2)(b).
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21.40
Manufactured Home Foundation Requirements
Manufactured
Home
Production
Date
Pre June 1,
1980
June 1, 1980
through
March 31,
2007
On or after
April 1, 2007
Home on Piers
(supported by
individual footings
or a slab)
s. Comm 21.04(2)
• No anchorage
required
• No footings
below frost
depth or frost
protection
required
s. Comm 21.04(2)
• No anchorage
required
• No footings
below frost
depth or frost
protection
required
s. Comm 21.04(1)
• Anchorage
required
• Footings
below frost
depth or
protected
Home on Basement or
Crawlspace
Additions to Home
Per any municipal
requirements relating to
basements or
crawlspaces for a preJune 1, 1980 dwelling
Per any municipal
requirements relating to
additions to a pre-June
1, 1980 dwelling
Per UDC general
requirements:
• Anchorage of
home to
basement or
crawlspace
required
• Footings of
basement or
crawlspace
below frost
depth or frost
protected
Per UDC general
requirements:
• Anchorage of
addition to its
foundation
required
• Footings of
addition below
frost depth or
frost protected
(see s. Comm
21.15(1)(e)
regarding
"floating"
structure if
home is not
supported on
frost-protected
Per UDC general
requirements:
• Anchorage
required
• Footings below
frost depth or
frost protected
Per UDC general
requirements:
• Anchorage
required
• Footings below
frost depth or
frost protected
2009-21-88
Chapter Comm 22
Introduction
Wisconsin has a keen interest in conserving energy because we import about 95 percent of what
we use. For our state's economic well-being, the legislature has enacted enabling legislation to
set building code standards for energy conservation.
This chapter of the UDC sets minimum standards for energy conservation for new one- and twofamily dwellings. It sets requirements for insulation and moisture protection of the building
envelope and capacity and efficiency requirements for heating, ventilating and air conditioning
systems.
The standards attempt to satisfy the human comfort needs of proper temperature, air movement
and humidity as well as economical and building-preserving construction and operation. To
assist you in better understanding these standards, we've included the following energy basics
section. Following that is the code section-by-section commentary.
Note that the effective date of the original energy conservation standards was December 1, 1978,
differing from the June 1, 1980, effective date of the other chapters of the UDC.
Special electrically heated dwelling standards were removed by March 2008 Legislative action.
Some Energy Basics
The following information is offered as background material to the intent and proper application
of the Ch. Comm 22 requirements.
Chapter Comm 22 requirements can be put into the four categories of heat loss control, moisture
control, ventilation design, and heating equipment requirements with some overlap between the
four.
I.
Heat Loss
The heat loss control requirements of Ch. Comm 22 are meant to limit heat transfer. Heat
transfer is the tendency of heat or energy to move from a warmer space to a cooler space
until both spaces are the same temperature. Obviously, the greater the difference in
temperatures, the greater the heat flow. There are three types of heat transfer:
-
Radiation - transfer of heat through space. An example is your body heat radiating out
a closed window on a winter night. The glass is cold so there is no radiation to you and
it is a poor reflector of your own heat back to you. Another example is sunshine
coming in through a window.
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Some Energy Basics
-
Conduction - transfer of heat through a material. An example is your warm hand held
against the inside surface of a cold exterior wall.
-
Convection - transfer of heat by moving masses of air. An example is heated air
leaking out through door and window openings.
The code does not say much about radiative heat losses. It does say a lot about conductive
and convective heat losses. Let's discuss these further.
A. Heat Loss By Conduction
1.
C-Values and k-Values
A measure of a material's ability to Conduct heat is its "C"-value which is
expressed in BTUs per (hour)(oF). A BTU is a British Thermal Unit which is the
heat required to raise one pound (about a pint) of water by one degree Fahrenheit
and is roughly equal to the heat given off by the burning of one kitchen match. A
human body gives off about 400 BTUs per hour. Since a C-value is a flow rate of
heat, it needs a per time unit similar to other rate measures such as speed,
"55 miles per hour." An hourly rate is also used in the C-value. Finally, as you
recall, heat flow is greater as the temperature difference increases. So the C-value
needs to be expressed in terms of what the difference is. For simplicity, it is taken
at 1 degree Fahrenheit difference.
Another term to be familiar with is a "k"-value which is merely the C-value for
one inch of material.
Typically, building components such as walls or ceilings consist of a "series" or
layers of different materials as you follow the heat flow path out. However, you
cannot add C-values together because if you were to take two insulating materials
with a C-value of .5 each and were to add them together, you get the result of a
total C-value of 1.0. This would mean that the heat flow rate has increased with
the addition of more insulating material. Obviously then you cannot add C-values
to find the "series" value.
2.
R-Values
Therefore, we now have to bring in the perhaps more familiar "R"-value which is
a measure of a material's Resistance to heat flow and is the inverse or reciprocal of
the material's C-value (R=1/C).
So if a material has a C-value of 0.5, it has an R-value of 2 (as 2 = 1/0.5). If you
have to add two materials in series or layers, say each with a C-value of 0.5, you
take the inverse of both to get an R-value for each of 2. These can be added
together to get a total R-value of 4. Usually materials are labeled or tables are
written so that the material's R-value is given [see Comm 22.20(5)(a)], which
relieves you of finding the inverse of the material's C-value.
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Some Energy Basics
3.
U-Values
For thermal heat loss calculations, we normally use "U"-values (U for
Unrestrained heat flow or transmittance) which is a material's C-value but also
includes the insulating effect of the air films on either side of the material. So it is,
therefore, a smaller number (less heat flow).
A U-value can also refer to thermal transmittance of a series of materials in layers.
To obtain a U-value for such an assembly, you add the individual R-values of the
layers and the air films on either side of the assembly. Then you take the
reciprocal of the total R-value to get the total U-value of the assembly (U = 1/R).
(As with C-values discussed above, you can not add U-values for series
calculations.)
4.
Heat Loss Calculations
The purpose of these C-, k-, R- and U-values is to be able to calculate heat loss
through a building component (wall, ceiling, floor). The basic equation is U x A
x TD = Heat Loss or
U x Area (ft2) x Temperature Difference (oF) = Conduction Heat Loss (BTU/hr)
So to find the heat loss per hour through a building section of wall, you:
-
determine its U-value by finding the inverse of the sum of individual R-values
for each layer of material;
-
decide on the inside and outside temperatures (in the case of the UDC, the
winter design temperatures are mandated);
-
measure the surface area of the building section;
-
multiply these numbers together and get a result in BTUs per hour.
If you did this for every different building section (solid wall, window, ceiling,
etc.), you could obtain the total heat loss through the envelope at design
temperatures, which is the worst case situation. Normally this maximum figure
along with the heat loss by infiltration (see discussion later) is used to size the
furnace or other heating source. It is referred to as the heating load.
If you wanted to know the total envelope loss for a heating season, you do a
degree-day calculation. A degree-day is the difference between 65°F and the
average temperature for a day if it was below 65°F. If this calculation is done for
each day of the heating season, you can find the total heating degree-days for the
year. This can be plugged into a modified version of the heat loss calculation as
follows:
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Some Energy Basics
U x Surface Area x Degree-days x 24 hours/day = Season Heat Loss
5.
U-Overall
One more term to know is U-overall or Uo which refers to the overall U-value of a
building component such as a wall or ceiling. For example, a wall will have
different individual U-values for the windows, stud cavities and stud locations.
The UDC sets a minimum Uo for each overall component surface. If a designer
has a large window area, more insulation will need to be placed in the wall
cavities or sheathing areas so that the overall or "average" wall surface U-value is
acceptable.
The U-overall value is calculated by taking the weighted average of the U-values
(not R-values) of the different parallel paths through the same component (wall,
ceiling or other) that you're dealing with.
6.
System Design
As an alternative, the system design method can be used so that more insulation is
put in the ceiling to make up for the extra windows. However, it is not a one-forone tradeoff because of the thermal transfer properties and mathematics of
reciprocals involved. Let's say you have an R-10 (U = 0.1) wall and R-10 (U =
0.1) ceiling of equal area. If you transfer half of the wall insulation, to the ceiling,
the wall becomes R-5 (U = 0.2) and the ceiling becomes R-15 (U = 0.07).
However, you can see that the wall U-value increased by 0.1 and the ceiling Uvalue only decreased by 0.03. (Remember U-values are used to calculate heat
losses.)
B. Heat Loss By Convection
As mentioned, the other mechanism of heat loss addressed by the UDC is convection,
or heat loss by air movement. In homes, this is principally heat loss by exfiltration and
infiltration. Exfiltration is the loss of heated air through building cracks and other
openings. Infiltration is the introduction of outside cold air into the building. This air
movement also causes discomfort (drafts) to occupants in addition to the heat loss itself.
The driving force for this exchange of air is the difference between indoor and outdoor
air pressures. Air pressure differences are principally caused by wind pressures and the
"stack" effect of warm inside air that tends to rise. Mechanically induced air pressure
differences can also occur due to such things as exhaust fans and furnace venting.
To calculate the heat loss by convection, we go back to the general heat loss calculation
and modify it to:
Heat Loss = Air's Heat Capacity x Air Volumed Exchanged x Temp. Difference
Hour
2009-22-4
Some Energy Basics
The volume exchanged can be determined by measuring or judging how many air
changes that a house goes through in an hour. To do this, you calculate the volume of
the heated space and multiply by an air change rate. For a UDC home, you can assume
a rate between 0.2 and 0.5 air changes per hour [see Comm 22.30(2)], usually with a
lower rate for basements with little outside air exposure, and higher rates for living
areas or exposed basements. If you have a 1500 square foot house on a crawl space
with 8-foot ceilings, the calculation of the volume exchanged can be:
1500 sq. ft. x 8 ft. x 0.5 Air Changes/hr = 6,000 cu. ft./hr
The heat capacity of air is a physical constant and is .018 BTU per (°F)(cu. ft.). The
temperature difference, which varies by site location, used is the same as for heat loss
by conduction. So the whole equation for this example is:
.018
BTU x 6,000 cu. ft./hr. x 90o = 9,720 BTUs/hr
( F)(cu. ft.)
o
This figure is the design or maximum heat loss by convection. If you wanted to figure
the total seasonal infiltration heat loss, you would perform a degree day calculation as
for the seasonal conduction heat loss calculation. You substitute the seasonal degree
days and the 24-hour multiplier for the temperature difference figure in the infiltration
heat loss equation above.
Another method of determining heat loss by convection is the crack method. For this
method you obtain the air leakage rates in cubic feet per minute for the doors and
windows from their manufacturers and multiply by the lineal feet of sash crack or
square feet of door area. (A more exact analysis would multiply the door infiltration
rates by 1 or 2 due to open/close cycles and add 0.07 cfm per lineal feet of foundation
sill crack.) This gives an air change rate per minute. This has to be converted to an
hourly rate by multiplying by 60. Then you substitute this figure for the air change rate
in the infiltration heat loss equation above.
C. Total Dwelling Heat Loss
If you add the heat losses by conduction and convection, you arrive at the total dwelling
heat loss for purposes of the UDC. Of course this figure is approximate and ignores
other means of heat loss. However, it also ignores the major heat gain from secondary
sources such as electric lights, human bodies, cooking, etc. So the figure tends to
overstate the heat loss but this ensures an adequately sized heating plant.
II.
Moisture Control
The second area of concern addressed by the UDC is control of moisture. The occupancy of
a dwelling produces a large amount of water vapor. As you may recall from weather
forecasts, warmer air can hold more moisture than cold air. In the winter, the inside air is
warmer than the outside, so if moisture moving outside by convection or dispersion (similar
to conduction) reaches too cold of air, it will "condense out." This occurs at the dew point
2009-22-5
Some Energy Basics
for that water vapor/air mixture. This condensation can be damaging to the building if it
happens inside part of the wall or ceiling construction. It can promote structural member
decay and lessening of the insulation's effective R-value.
There are three methods of reducing the possibility of condensation--vapor retarders and
cold-side venting.
A. Vapor Retarders
A vapor retarder (sometimes called as a vapor barrier) acts to resist the movement of
moisture through a section of the building envelope. A vapor retarder's efficiency at
doing so is measured by its permeability in "perms." A perm is one grain of water per
(hour) (square foot) (inch of mercury vapor). The lower the number, the more resistant
is the material to moisture flowing through it.
The UDC requires a perm rating of one or lower for vapor retarders in homes.
For a vapor retarder to work properly, it must be placed on the warm-in-Winter side of
the building envelope so moisture does not gain entry into the wall or other building
component. The barrier also needs to be continuous with seams and holes lapped or
sealed. Otherwise, warm moist air will easily bypass the vapor retarder and enter the
wall or ceiling through leaky joints or penetrations. This bypass effect can be
substantial and leads to greater heat loss, structural member damage &/or mold growth.
The requirement for a vapor retarder in ceilings and walls prevents deterioration of the
wood structural members caused by condensation within the wall cavities or ceiling
cavity. Vapor condenses when it comes in contact with material that is at a temperature
lower than its dew point. The vapor retarder is required to keep the moisture out of the
insulated wall cavities where the dew point temperature is reached. This temperature
typically occurs within the wall cavity and thus would condense out water vapor before it
can escape from the dwelling. If condensation is occurring on the interior surfaces of the
dwelling, it is occurring at points where the buildings materials are cooler than the vapor's
dew point. This situation is usually first evident on windows where the glass provides a
colder surface on which condensation can occur.
Additional areas where condensation occurs are generally at corners of rooms at the
exterior walls. This area is subject to condensation for a number of reasons. The
temperature at the corners is generally cooler due to the fact that it is difficult to insulate
at this location due to the method of construction. The insulation may be further reduced
due to the roof system allowing less insulation to be placed above the corner.
Condensation also occurs in areas with poor air circulation such as closets.
Recent studies have shown that air exfiltration may be the greatest cause of condensation.
At the corners of the walls is the area with the greatest potential to obtain air exfiltration
if precautions are not taken at the time of construction. The vapor retarder installed may
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Some Energy Basics
not be complete at the corners due to the meeting of the ceiling and wall area. This
allows additional moisture to pass through the corners and to be subject to condensation.
When condensation occurs, an environment is now created that is conducive to the
formation of mold. This could occur on the surface or with wall/ceiling cavities.
Elimination of the vapor retarder requirements at the interior finish would only allow the
condensation, mold formation and deterioration of the wood to occur within the structural
elements of the dwelling. Proper precautions during the original construction stages are
generally adequate to prevent condensation from occurring. In some cases where the
lifestyle of the inhabitants of the dwelling is such that a large quantity of humidity is
produced, an occasional airing out of the dwelling by exhaust fans or opening windows
should be employed by the occupants. Such ventilation may also be necessary when
homes are built especially tight and natural infiltration is low.
B. Cold-Side Venting
The other means of controlling moisture is cold-side venting. This is usually employed
in attics and unheated crawlspaces. The venting removes excess moisture that bypassed
the ceiling vapor retarders or comes out of the earth in the crawl space. This venting is
usually done by natural means through the use of grills or louvers from the space to the
outside. However, for that to work, there must be high and low venting in the case of
the attic or cross ventilation in the case of the crawl space.
Cold-side attic venting also keeps the roof cooler so that there is less melting of snow
and contributes to less creation of ice dams at the eaves in the winter. It also helps
dissipate summertime attic heat, which increases comfort and reduces cooling costs.
C. Impervious Insulations
Thus use of closed-cell foam plastic insulation or similar non-absorbent insulating
materials that are unaffected by moisure condensation is another effective method used
for some designs of dwellings to deal with this issue.
D. Moisture Control During Construction
Unless proper construction techniques are utilized during construction, serious problems
can occur as a result of water vapor that is trapped inside and then causes deterioration of
gypsum wallboard.
Over the years we have seen many improvements in both materials and methods in home
construction. Often times the use of a new material required the change in a technique or
method of construction previously unheard of. Most building codes are only a reflection of
our latest achievements in technology and engineering. The vapor retarder requirements in
the Uniform Dwelling Code are a reflection of state of the art insulation techniques. Simply
stated, the purpose of the vapor retarder is to prevent (as much as possible) water vapor from
penetrating into the insulation and thereby reducing the effectiveness of the insulation. The
problem is that builders who are not familiar with the use of vapor retarders, particularly
during winter construction months, can inadvertently create problems for the homeowner if
2009-22-7
Some Energy Basics
precautionary measures are not taken during construction. We offer the following
suggestions to incorporate in construction procedures, especially during winter months:
1. Do not allow gypsum board to pick up excess moisture prior to installation.
2. Make sure attics are insulated prior to putting heat into the home for gypsum board taping
and finishing. Many builders neglect to do this and create condensation problems when
the water vapor condenses upon hitting the cold, attic air above the gypsum board.
Gypsum board ceilings should be hung and insulated prior to putting heat into the home.
3. Make sure all heating appliances, i.e., furnaces, temporary heaters, salamanders, etc., are
vented to the outside of the home. Builders who do not follow this warning are adding
additional water vapor created by combustion of heating fuels.
4. Make sure all required attic ventilation is installed and operable to remove any water
vapor trapped in the attic.
5. Provide a means for the water vapor in the home to escape; such as periodic opening of
windows, doors, etc. Perhaps the installation of a humidistatically controlled exhaust fan
is necessary, particularly where electric baseboard heat or heat pump systems are utilized.
6. Do not overload gypsum board ceilings with insulation beyond their capacity. See
s. Comm 21.02 (1)(a) of this commentary.
Incorporation of these techniques will avoid major problems with condensation. These
methods are not new and have been proven successful by many hundreds of builders
operating in climates such as ours.
E. Post-Construction" Moisture Control Problems
As discussed in the basics section of this commentary chapter, moisture must be dealt
with in all homes. The following is a general discussion of typical symptoms, causes and
prevention techniques regarding moisture problems in homes. It is intended as
background information to help explain some UDC requirements. Additional
recommendations above and beyond the UDC minimums are included for homeowners
who may experience more severe moisture problems.
1.How can you determine if a home has a moisture problem?
You can get a good idea of whether your home has an excess moisture problem that may
lead to damage by checking for the following symptoms.
• Extensive condensation on windows during the heating season. Some condensation is
normal. Condensation that streams off the window and puddles on the frame and sill
when outside temperatures are 10°F or above and inside temperatures are above 65°F
indicates humidity levels are probably too high.
o If condensation is limited to the inside surface of storm windows, then your
primary windows may be allowing moist interior air to leak by them. Because of
the "stack" pressure effect, this problem may be worse on second floor windows.
2009-22-8
Some Energy Basics
o If condensation is limited to the inside surface of the primary windows, then your
storm windows may be allowing cold air to leak by them which then cools the
primary window.
• Staining and mold on window frames.
• Mold or water spots in numerous locations on the inside surface of outside walls. Common
trouble spots include closets on outside walls; corners between two outside walls or
between an outside wall and ceiling; and outside walls behind furniture; or other areas
where air circulation is limited.
• Soft or buckling interior wall surfaces. Gypsum board is a common interior surface. When
dampened it may pull away from studs or ceiling rafters. Additional moisture may cause
the gypsum board to crumble.
• Staining or warping of exterior siding.
• Paint peeling from exterior siding, especially extensive peeling of paint down to the primer.
If you have not experienced any of these symptoms, the home probably does not have a moisture
problem. However, it may be a good idea to consider some of the measures in the following
Section III to assure that future problems do not develop.
2. What are typical causes of moisture problems in homes?
Through breathing and normal daily activities, each member of a household produces about
seven pounds of water vapor. Naturally this number varies greatly depending on living
habits. This water vapor becomes part of the air. However, air can hold only a limited
amount of water vapor. This amount depends on temperature. The higher the temperature
the more moisture the air can hold. When more moisture is introduced into the air than it
can hold, some of the moisture will condense on surfaces. If cold surfaces sufficiently cool
the surrounding air, condensation will occur on that surface even though the remaining room
air is not saturated with moisture. The frosted cold beverage glass in summer is an example.
In most older homes there is enough movement of air into and out of the house that moisture
does not build up and only small amounts of condensation occurs. However, when air leaks
into and out of a house it not only takes moisture but heat as well. In order to make homes
more energy efficient, builders have been trying to seal cracks and cut air leaks.
These efforts to tighten homes have meant that more moisture remains in the home. Unless
controlled ventilation is added, moisture accumulates, and condensation occurs near the
ceiling on outside walls or on outside walls of closets. These areas generally have cooler
surfaces. If condensation persists on these surfaces, molds and mildews may develop. In
addition, fungal growth and possible deterioration of material may occur when temperatures
are at or above 50°F and the material remains wet. Such fungal growth could damage wood
members in extreme circumstances.
3. Besides the UDC requirements, what measures can help prevent moisture problems?
2009-22-9
Some Energy Basics
•
Reduce Moisture Production In The Home
o One way to substantially reduce the chances that condensation will occur either on
inside surfaces or within walls is to keep indoor moisture levels low. The first
step is to reduce the amount of moisture produced in the home. Some major
sources of moisture that can be controlled are listed below.
o Prevent moisture from entering through basements. Many basements feel damp in
the summer due to condensation of moisture from the air on cool basement
surfaces. However, in some cases damp basements may be due to ground
moisture entering the home through basement walls. Cracks or stains on
basement walls and floors are signs of dampness entering through these surfaces.
You can check whether dampness is coming through walls by using a
simple patch test. Tape a piece of plastic sheeting tightly against the
basement wall where you suspect moisture penetration. After a couple of
days pull the patch off and look for signs of moisture on the wall side of
the patch. If you detect moisture, it means moisture is coming through the
wall rather than condensing on the walls.
If you suspect a basement water problem, check the surface drainage
around you home. Most basement water problems result from poor
surface drainage. Make sure that the ground slopes away from the
foundation. Consider installing gutters. If you have gutters, make sure
they are clear of debris and functioning properly. Downspouts should
direct water away from the foundation.
o Do not store large amounts of firewood in the basement. Even seasoned wood
can contain large amounts of moisture. It also may be a source for fungus.
o Other ways you can reduce moisture generation:
Vent clothes dryers outdoors;
Don't line dry clothes indoors;
Limit the number of houseplants;
Cover kettles when cooking;
Limit the length of showers; and
Do not operate a humidifier in the wintertime unless your indoor relative
humidity is below 25 percent.
Be sure any crawlspace floors have a vapor retarder covering.
o If problems persist, you should also check for any blocked chimney flues that may
be preventing moisture-laden flue gasses from exhausting out of the house.
o Correct any plumbing and roof leaks. If ice dams are a problem, consider more
attic ventilation and adding insulation.
•
Add Mechanical Ventilation
o A second way to reduce moisture levels is to add mechanical supply and exhaust
ventilation. As an added benefit, ventilation will reduce concentrations of other
possible air contaminants such as combustion by-products from heating, cooking
and smoking.
o A widely recommended ventilation rate for homes is one half air change per hour.
In a 1,200-square-foot house with 8-foot high ceilings, there are about 9,600 cubic
2009-22-10
Some Energy Basics
feet of air. To meet the ventilation standard, half of that amount or 4,800 cubic
feet of air must be exchanged every hour. This roughly equals 100 cubic feet per
minute (cfm) of air exchange. Even in a tight house some of this air exchange
occurs naturally.
o However, in a house that is experiencing severe moisture problems, it can be
assumed you are getting less than one half air change per hour. A balanced
ventilation system should be used to make up the remaining necessary air
exchange. A balanced system is one that not only exhausts stale air but provides a
source of fresh replacement air. Currently the UDC per Comm 23.02(3)(b)2. only
mandates that 40% of exhaust ventilation be made up through another means.
Without proper replacement air the home could have what is known as negative
air pressure.
o Negative pressure could cause exhaust gases from your furnace or water heater,
which should be going up your chimney or out a vent, to be sucked into the living
space.
o Additional ventilation is needed only during the heating season. When you
provide controlled ventilation for your home, the heat lost is relatively small. For
a 1,200-square-foot home, the cost of this lost energy and the electricity to run the
fan would amount to about a dollar a day assuming you heat with the most
expensive heat source, electric baseboard. This cost should be much less if you
heat with gas or other fuels. Also, some ventilation systems can reclaim a portion
of the heat (up to 80%) from the exhaust air by heat-recovery ventilators. This
could help reduce energy costs.
• Stop Moisture At The Inside Wall Surface (In Addition To The Required Moisture Vapor
Retarder)
o In addition to reducing moisture levels of the interior air, carefully seal all
openings in the inside surface of all exterior walls to prevent moist air penetration.
This includes joints around window and door casings, baseboards, electrical
outlets and switches and any other penetrations. Gaskets for electrical
penetrations are now commonly available, be sure that they extend to the outside
edge of the cover plate of electrical devices.
Relative Humidity
In winter, the ideal relative humidity range for comfort is 30 percent - 45 percent. A lower
humidity may cause excessive skin evaporation which in turn will cause an undesired cooling
effect. For the sake of protecting the structure from damage due to excessive moisture, an ideal
relative humidity range of less than 45 percent is recommended. Therefore, to provide comfort
and still protect the building, a relative humidity range between 30 percent to 45 percent is
recommended.
In summer, the ideal comfort range is 30 percent - 50 percent. Higher humidity won't allow
adequate skin evaporation and the resulting desired cooling effect.
2009-22-11
22.01(3)
III.
Mechanical Ventilation
As the code has mandated tighter home construction, the UDC has had to provide increase
of mechanical ventilation as an alternative to infiltration to maintain indoor air quality so
excessive humidity or other pollutant levels are checked. This has taken the form of
required exhaust ventilation for rooms with a toilet, tub or shower and for kitchen exhaust.
A designer may decide to use an air-to-air heat exchanger to satisfy the exhaust requirement,
while at the same time recovering heat from the exhausted air. This is done by moving the
exhausted air past the intake air with a heat exchanging barrier between the two air streams.
IV. Equipment Efficiency Requirements
The final area that Ch. Comm 22 regulates is heating and cooling equipment efficiencies.
Subchapter I  Scope and Application
22.01(3) Scope
Altough homes that are heated with renewable sources of fuel, such as wood, are exempt from
the insulation requirements, they are still subject to the moisture control requirements for vapor
retarders and ventilation. These are needed to protect framing and keep insulation dry and
protected from degradation.
22.02(2) Demonstration Method of Compliance
As there are more than one method, submitters of plans & calculations should clearly
communicate which method of compliance is being provided for the dwelling.
Subchapter III  Materials and Equipment.
22.20(4) Material Installation
This section requires all insulation, mechanical equipment and systems to be installed per the
manufacturer’s installation instructions which are to be available at job sites during inspection.
22.20(6) Building Certification
This section now requires that a permanent certificate of insulation R-values and fenestration Ufactors be provided on or immediately adjacent to the electrical distribution panel. If REScheck
or REM/Rate software program was used, that certificate print-out shall be provided. Otherwise,
a copy of the prescriptive table (Table Comm 22.31-1 or Comm 22.31-4) may be used with the
installed R-values highlighted. (Note that Rescheck also provides a method for sizing the heating
plant as required by s. Comm 23.03. If some other method is chosed for demonstrating thermal
envelope compliance, then Rescheck or an alternative means of showing proper heating plant
sizing is still needed.)
22.21(1)&(1) Protection of Insulation
2009-22-12
22.35
This section now requires blanket insulation to be held in place by a covering or mechanical
fastening. Comm 22.21(2) adds cold-in-Winter side windwash protection of air-permeable
insulation, thus keeping insulation in place and maintaining the R-value of that insulation.
Normally the exterior sheating would do this, but where that is not present, some other vaporpermeable material, such as housewrap would be required.
Subchapter IV  Dwelling Thermal Envelope
22.31 Envelope Compliance
Envelope compliance may be by prescriptive method of Comm 22.31(1) by either complying
with Table 22.31-1 or Table 22.31-4 or alternatively, per Comm 22.31(2) by showing the the
overall envelope U-value times Area complies. The latter method may be done by hand
calculation or more typically by the use of the free software program, Rescheck, available from
the federal government at www.energycodes.gov . Rescheck also gives some additional credit
for higher efficiency heating equipment. Finally, compliance may be shown per Comm 22.51 by
calculations or software that models the whole house energy usage. Remrate is a type of
acceptable software for that purpose.
Although the note here implies that Rescheck version 4.0 or higher would be acceptable, it
would actually need to be high enough that “Wisconsin 2009” code is listed as an available code
option.
22.32 (1) Ceilings With Attic Spaces.
This section permits the use of R-38 in the attic space in lieu of R-49 speicified in Table 21.23-1
as long as the R-38 inslulation covers the entire attic area including over the exterior wall top
plates. This could be accomplished with the use of “energy heel” trusses. The height of the heel
would depend on the type of insulation used to attain the R-38 insulation value.
22.33 Slab Floors
Shallow slabs less than 12" below grade must meet Table 22.31-1 or 22.31-4 for Unheated Slab
R-value with perimeter insulation. Heated slabs of any depth with embedded, uninsulated
heating ducts or pipes require slab insulation throughout, with additional insulation at the
perimeter. Horizontal slab insulation that projects away from the building shall be protected by
either pavement or a minimum of 10 inches of soil. See UDC Appendix drawings showing
acceptable and unacceptable perimeter insulation in terms of ensuring the edge of the slab is
properly insulated.
22.34 Crawl Spaces
Requirements for crawl space insulation protection, vapor retarders, and ventilation, which were
formerly in various places of Comm 21 & 22, have been put into single place in Comm 22.34.
Option of insulating the floor over crawl space and providing crawl space venting or else
insulating the crawl space walls and not venting that space is made clear by code provisions.
22.35 Sunroom vs Screen Porch
2009-22-13
22.36
This option for reduced insulation levels is only available to heated sunrooms with opague walls
and glazing. It is not available to heated screen rooms with only screens for a portion of the
walls.
22.36 Fenestration
Fenestration is an architectural term for windows and doors. The UDC requires generally
requires them to be certified under the NFRC 100 standard for the values used, which is easily
verified in the inspection of the window label on each unit. Where windows are not labeled, the
conservative, default table values must be used for determining compliance. The code allows a
single door and a single window to be exempt from door and window requirements which
permits the installation of elements such as stained-glass windows
Different types of window operating hardware will produce different U-values for similar-sized
windows. Therefore, a 3'-0" x 3'-0" double hung window would have a different U-value from a
3'-0" x 3'-0" fixed window sash. Similar size windows produced by two different manufacturers
would most likely also have different U-values. Averaging of U-values is per Comm 22.36(1).
22.37 Air Leakage
Air leakage at fenestration and at other penetrations in the envelope are to be sealed properly per
Comm 22.37(3) requirements. Comm 22.37(4) was added to the code to provide specific
guidance on recessed lighting installed at envelope areas, without leading to overheating fires.
22.37 Air Infiltration Barrier
The UDC does not define materials to be used as an infiltration barrier. It does require them to:
1.
Be installed on the interior face, typically as part of the vapor retarder, or on the
exterior face of the wall, typically as a house wrap or caulked building panels.
2.
Form a continuous barrierover the walls of the building from the bearing points of
the roof to the top of the foundation.
3.
Seal all seams, joints, tears, and punctures.
Additionally, the department has determined such infiltration barrier construction:p
1.
Be water vapor permeable to prevent moisture problems within the wall if installed
on the cold sid of the wall. The perm rating must be significantly higher than the interior
vapor retarder.
2.
Restrict infiltration to an appreciable extent.
These materials include:
• Spun bond polyolefin sheets, with taped joints. (Ex: Tyvek by Dupont.)
• Micro-perforated polyethylene (Valeron) film sheets, with taped joints. (Ex: Air Stop
by Diversi-Foam Products.)
• Tongue and groove extruded polystyrene, with taped joints.
• Other building panel sheets such as foam sheathing or plywood sheathing with taped
joints, regardless if the panels have butt or tongue and groove edges
2009-22-14
22.38(1)
22.38(1) Paint as a Vapor Retarder
Advances in paint chemistry have made certain paints available to contractors which, when
appliid at conventional spread rates, provide a vapor retarder with a perm of 1 or lower.
This department has reviewed vapor retarder paints for application meeting the intent of Comm
22.38; however does not widely recommend them. The evaluation method used to determine the
acceptability of the paint is based on the paint's:
1.
2.
3.
4.
Perm rating based on ASTM test E-96.
Scrubability as based on ASTM test D-2486.
Evaluation of manufacturer's recommendation for the paint's use.
Labeling of all paint containers.
All test results submitted shall be from recognized independent testing agencies. The department
feels that the above assures that specifically reviewed manufacturer's products will perform and
not break down when applied as instructed by the manufacturer. Such vapor retardant paints
shall be installed per the testing of that paint, thus if it is applied to a smoother surface for test,
that is required for the actual application.
Two coats of vapor retarder paints are typically required to take into account variances in field
application. If no materials approval is provided, then the UDC inspector may require two coats
and proper documentation of the paint perm rating. Also any texturing must be applied after the
vapor retarder paint. Holes made in the wall surface after covering with vapor retarder paint
should be treated with the same sealing and repair as one should use for holes in other vapor
retarder materials typically installed behind the typical gypsum wallboard used on ceilings &
walls.
In order to assure building officials and owners that a vapor retarder paint has in fact been
installed and the intent of Comm 22.38 met, a certificate of compliance (see following sample
certificate) may be filled out and submitted to the building official with a copy to the owner. In
addition to the certificate, the contractor should provide the inspection agency with the labels
from the paint cans that were used by the applicator.
The following is the recommended procedure to be followed by building inspection agencies to
assure compliance with the vapor retarder requirement and yet to allow limited use of vapor
retarder paint. Procedure to be followed:
1.
2.
3.
At the time of plan submittal, the builder should state or have shown on the plans what
type of vapor retarder is to be used in the dwelling. Either manufacturer's data or a
Wisconsin Materials Evaluation number shall be presented to show compliance by the
chosen paint.
At the time the plan is approved, the inspector should provide a blank Certificate of
Application if one will be locally required.
At the time the insulation/rough energy inspection is made, the inspector will be able
to determine where the standard vapor retarder was applied in the dwelling.
2009-22-15
22.38(1)
4.
5.
At the final inspection, the contractor should supply to the building inspector the
completed certificate as well as the labels from the paint cans.
The inspector may then destroy the labels and the Certificate of Application can be
filed with the building file.
2009-22-16
22.38(2)
VAPOR RETARDER PAINT
CERTIFICATE OF APPLICATION
THIS CERTIFIES THAT A VAPOR RETARDER PAINT HAVING A PERM RATING
BELOW 1.0 WAS APPLIED TO THE FOLLOWING STRUCTURE:
PAINT MANUFACTURER:
COMMERCE MATERIAL APPROVAL NO. (If Applicable)
SUPPLIER:
GALLONS USED:
LABELS SUBMITTED:
YES
CEILINGS - TOTAL SQUARE FEET COVERED:
WALLS - TOTAL SQUARE FEET COVERED:
NUMBER OF GALLONS USED ON: 1st COAT
APPLICATION MADE BY NAME:
ADDRESS:
SIGNATURE:
2009-22-17
2nd COAT
NO
22.38(2)
22.38(2) Vapor Retarders Not on Warm Side
Occasionally it occurs that a wall will have two materials orlayers that may act as vapor retarders.
It is important in this situation that the better vapor retarder (lower perm rating) be placed closer
to the warm side. Also, extreme care should be taken to make the interior vapor retarder
continuous with good joint and penetration sealing. This will help avoid condensation of
moisture in the wall.
In some other dwelling designs, double walls are constructed with insulation in both walls.
Often this is to avoid making electrical box and other penetrations in the vapor retarder. A single
vapor retarder is placed between the two walls. This conflicts with the requirements that vapor
retarders be placed on the warm side of all insulation. However it may be acceptable depending
on the distribution of the insulation between the two walls. If there is enough insulation on the
exterior side of the vapor retarder, the air temperature in the insulation at the interior face of the
vapor retarder may still be warm enough to prevent condensation.
A DEW POINT CALCULATION estimates expected temperatures throughout the
thickness of the wall. Interior temperature, exterior temperature, and wall component
R-values must be known. Additionally, a "design" interior air relative humidity must be
assumed. Since typical wintertime reported indoor humidities range from 40 percent to 60
percent, the department will accept 50 percent as an average indoor relative humidity (RH)
design value for such a calculation.
In order to do such a calculation, a person must have access to a psychrometric chart or
table to determine dew points throughout the wall section given specific design
temperatures, RH, and wall component R-values.
Example: Fictional Wall
R = 10, uniformly distributed across thickness of 4 inches
RH = 50% (interior)
Temp = 70°F interior and -10°F exterior
This would result in condensation if interior air was lowered in temperature or exposed to a
surface temperature of approximately 50°F. In this wall, the 50°F dew point occurs at 1
inch from the interior surface. Therefore, a recessed vapor retarder must be to the inside of
this 1-inch limit.
Detailed calculations shall be submitted for each specific project where a designer wishes
to recess a vapor retarder into the wall cavity.
22.38(3) Vapor Retarders Under Concrete Floor
Although there is a requirement for turning the under-concrete floor vapor retarder up at the
edges of slab and running it to the top of the slab, this will in most cases, for basements, ground
floors and crawl spaces, be equivalently met by just extending the vapor retarder beneath the
slab, over the foundation and to the basement/ground floor wall. For this case the the thickness
of the concrete footer and foundation wall provides a 1.0 perm or better vapor retarder rating.
2009-22-18
22.42
For a slab on grade installation the vapor retarder shall extend to the point at which the slab is
thickened.
22.38(4) Vapor Retarders Prohibited on Concrete or Masonry Walls
The code now prohibits installing a vapor retarder of a 0.1 perm or less rating on or in front of
masonry or concrete below grade foundation walls. This is avoid the potential for moisture from
adjoining earth being trapped between an interior vapor retarder and the wall and possibly
causing degradation and mold.
22.39 Attic Ventilation
Attic ventilation is generally required for air-permeable insulation is installed. This means that
attic ventilation is not required above closed-cell foam insulation.
The code requirements of these sections for venting areas are based on effective venting area.
Louvers and screening greatly decrease the effective venting of attic vents. Usually the effective
venting area of a vent is indicated on it. Otherwise the following is a guide:
Obstruction in Ventilator
(Louvers and Screens)
1/4 inch mesh hardware cloth
To Determine Total Free Area of Ventilator
Multiply Gross Area by:
1
1/8 inch mesh screen
0.8
No. 16 mesh insect screen (with or without plain metal louvers)
0.5
Wood louvers and 1/4 inch mesh hardware cloth
0.5
Wood louvers and 1/8 inch mesh screen
0.44
Wood louvers and No. 16 mesh insect screen
0.33
Regarding turbine vents, the effective area is equal to the bottom opening area.
Regarding power vents, manufacturer's requirements should be followed. Otherwise an installed
mechanical ventilation capacity of 0.25 cfm per square foot of attic floor area is acceptable.
Additionally, adequate air intakes must be provided. Control of the fan must be provided by a
humidistat or combination humidistat/thermostat. A humidistat setting of 90 percent is
acceptable.
Subchapter V  Systems
22.40 Outdoor Design Temperatures
The design of heating equipment to satisfy the heating load is regulated by ss. Comm 23.02 and
23.03. Those sections refer to the UDC Appendix table for determining outdoor design
temperatures.
22.42 Insulation of Ducts Under Slabs-on-Grade
2009-22-19
22.42
Section Comm 23.08 (4) states that the minimum insulation value for under ground ducts is R-5.
As this section is more restrictive, the R-8 minimum is required. See following drawings.
2009-22-20
22.42
DUCT
R-8 duct insulation
R-10 perimeter insulation
Acceptable design for insulated duct outside building thermal envelope of an
unheated slab on grade design
DUCT
R-10 heated slab insulation
R-15 perimeter insulation
©
Acceptable design for heated slab-on-grade design as duct is within building
thermal envelope
2009-22-21
22.43(6)
22.43(6) Tapes with Rubber-Based Adhesives Prohibited
Duct system joint sealing is required by Comm 22.43(1) where those ducts are not completely
within the conditioned space. “Duck" or "duct" tape typically has rubber-based adhesives.
Comm 22.46 Replacement Furnace & Boiler Efficiencies
Normally replacement equipment may meet the code at the time of their original installation per
s. Comm 20.07(61) definition of repair, as opposed to alterations that need to meet the current
code. (Note that the federal government has evolving minimum heating appliance efficiencies
that apply to all residential installations, new or replacement.) However, this section requires that
replacement furnaces also comply with specified duct sealing criteria and that replacement
boilers comply with circulating motor limits. Alternatively, the replacement equipment may
instead just comply with the more stringent Wisconsin efficiency requirements of Table 22.31-3
(as for new construction that is permitted reduced thermal envelope insulation levels) without
duct sealing or circulating motor limits.
Subchapter VI  Simulated Performance Alternative
22.51 Documentation of Simulated Performance Alternative
Compliance by Comm 22.52 is typically shown by REMrate software that models the whole
house energy usage. REM/Rate software is proprietary to certain providers. The version
available after April 1, 2009 must be used, thus any print-outs with version 12.6.0 or less is not
acceptable to show compliance with the current code. Note that the example given on the
following pages meet the Comm 22.52 documentation provisions of the code, including the
inspection checklist of the components of that system.
2009-22-22
22.51
SAMPLE
REM/Rate Home Energy Rating Tool
Rem/rate version 12.61 - Wisconsin
Uniform Dwelling Code Compliance Option Reports
For more information contact:
Homes Department
Focus on Energy
431 Charmany Dr
Madison, WI 53719
1-800-762-7077
2009-22-23
22.51
SAMPLE
2009-22-24
22.51
SAMPLE
2009-22-25
22.51
SAMPLE
2009-22-26
22.51
SAMPLE
2009-22-27
22.51
SAMPLE
2009-22-28
22.51
SAMPLE
2009-22-29
22.51
SAMPLE
2009-22-30
22.51
SAMPLE
2009-22-31
22.51
SAMPLE
2009-22-32
22.51
SAMPLE
2009-22-33
22.51
SAMPLE
2009-22-34
22.51
SAMPLE
2009-22-35
22.51
SAMPLE
2009-22-36
22.51
SAMPLE
2009-22-37
22.51
2009-22-38
22.51
2009-22-39
22.51
Roof Wall
top plates
If no extruded polystyren sheathing
Wall/Window Head
exterior finish
window header
plate at window head
window frame
window sill
Wall/Window Sill
plate at window sill
bottom plate
sub floor
floor joist header or band joist
If no
sheathing
Floor/Foundation
sill plate
foundation wall
foundation insulation
Caulk, Gasket or Seal:
Mandatory; also (not shown):
- All utility penetrations
- Between door thresholds and subfloor
- Between joist header and foundation
- Exterior joints at cantilevered floors, bay windows and
soffitts (floor to wall, wall to roof, but not wall to wall joints)
- Separate wall panels in panelized construction
2009-22-40
22.51
bottom plate
Wall/Intermediate Floor
subfloor
floor header joist or band joist
top plates
double bottom plates
Wall/Foundation
foundation wall
If no sheathing
2009-22-41
Chapter Comm 23
Subchapter I  Scope
Note that a change to the boiler code Comm 41.02(1) on December 1, 2008 made installation of
new outdoor wood-fired boilers that serve UDC dwellings fall into the scope of the UDC
regulation.
Subchapter II  Design
23.02 Sizing of Heating Equipment
Note that the outdoor air design temperatures for heat loss calculations shall be taken from the
figure in the UDC Appendix or from within the Rescheck software. Indoor design temperatures
is established in s. Comm 22.40 as being 70 degrees for heated areas.
23.02(3)(a) Exhaust Fan Termination
Question: Can an exhaust fan terminate inside a garage, crawlspace or attic near a vent?
Answer:
No. It must have an exterior termination. The air currents may otherwise draw the
exhaust back into the space. It is recommended that where exhaust terminates in the
soffit space of an overhang, the soffit been “blanked-off” for a recommended 2’
distance on either side of that termination unit.
23.02(3)(b) Balancing of HVAC Equipment
Question: What does "balanced" mean?
Answer:
It means that the ventilation system should not produce excessive positive or
negative pressures in the dwelling. Excessive negative pressure can cause chimney
or vent back-drafting of combustion products or even carbon monoxide poisioning.
Commentary from Comm 22 deals with leaking of buildings and the moisture that
moves into or out of a dwelling, see those comments for related balance issues.
23.02(3)(b)2. Outside Air Intake Sizing
Question: How do I size the outside air intake to balance my dwelling's exhaust.
Answer:
The minimum amount of make-up air must be 40% of the total exhaust. Size the
duct considering the minimum and maximum flowrate conditions specified in s.
Comm Table 23.07, Duct Velocities. Per this table, the minimum duct velocity is
500 ft/min and maximum allowable is 800 ft/min for outside air intakes.
Example:
Determine size of make-up air duct required for these exhaust systems.
Range hood
Bath exhaust 1
Bath exhaust 2
TOTAL
=
=
=
180 cfm (intermittent)
50 cfm (intermittent)
75 cfm (intermittent)
305 cfm (intermittent)
2009-23-1
x
x
x
x
40%
40%
40%
40%
=
=
=
=
72 cfm
20 cfm
30 cfm
122 cfm
23.02(3)(d)
Based on the formula of Quantity = Velocity times Area (Q=VA). THEREFORE:...
Check Minimum Duct Size of A=Q/V, or A=122/800, or A=0.1525 sq. ft. x 144 =
21.96 sq. in. (required)
Try 4” round duct = 3.14 x radius squared = 3.14x2x2 = 12.56 sq. in. (too small)
Try 6” round duct = 3.14 x radius squared = 3.14x3x3 = 28.26 sq. in. (OK since >21.96
in2)
Check maximum duct size A = 122/50 = .244 x 144 = 35.136 sq. in. (therefore 6" round
duct is OK since it is smaller than this)
Not doing the calculation described above to appropriately size the air intake may result in an
oversize intake and cause the problems noted in s. Comm 23.07. The HVAC system shall be
tested by the installer per Comm 23.18 to make sure the design amounts of air are actually
provided when the system operates.
23.02(3)(d) Ductless Recirculating Fans
Question: Are there any department-approved ductless recirculating bathroom fans that may
be used in lieu of natural ventilation or mechanical ventilation?
Answer:
No. In rooms with a toilet, tub, or shower, it is required by (3)(d) that mechanical
exhaust fans, ducted to outside the dwelling, be installed even where openable
windows are present. The only exception is for dwellings without electrical service.
Subchapter III  Heating Equipment
23.03 Selection of Equipment
See s. Comm 23.02 regarding sizing of heating equipment.
23.04 Listing of Equipment
All heating equipment including woodstoves and decorative gas appliances (gas fireplaces) must
be listed by a recognized testing agency. An important part of inspecting an appliance's
installation is to check against its listed installation requirements. Therefore, it is good practice
to refer to the installation manual when installing and inspecting the installation. Per s. Comm
23.18(1), an appliance's manual is required to be left with the owner. Per s. Comm 20.09, it can
be required for plan review or inspection by the inspector.
23.04(2)(b) Unvented Furnaces and Space Heaters and Fireplaces
Portable kerosene and other types of unvented heaters are being advertised and sold in
Wisconsin. However, neither the Commercial Building Code nor the Uniform Dwelling Code
permit their use, even if provided with oxygen depletion sensors. Use of such heaters is
prohibited because the heaters are not vented and can cause a buildup of carbon monoxide and
moisture in the room. Further, the heaters require frequent refueling which can lead to spillage
and additional fire hazard.
Question:
If unvented heaters are prohibited by the UDC and the Commercial Building Code,
why are kerosene, natural gas, alcohol fueled heaters still being sold?
2009-23-2
23.04(6)
Answer:
These heaters are not necessarily illegal in structures not covered by either code,
such as pre-1980 dwellings or agricultural buildings. However, some
municipalities have adopted ordinances prohibiting unvented heaters in pre-1980
dwellings or other buildings.
Question:
Answer:
Can an unvented heater be used in a residential garage?
Only in detached garages, since the UDC Comm 20.07 (35) defines an attached
garage as part of the dwelling. Therefore, the attached garage would have to
comply with all chapters of the UDC. Most municipalities have their own
ordinances of codes covering construction of accessory buildings, such as detached
garages.
23.04(5) Dual Use Water Heaters
See the checklist at the end of this chapter for code issues relative to water heaters used for
potable and space heating purposes.
23.04(6) Location
Question: How do I determine if a furnace is listed for installation in a bedroom, bathroom,
closet or garage?
Answer:
Although this information may not be shown on the unit, it does need to be covered
in the installation instructions which must be provided to the owner, per s. Comm
23.18. Many times these installation instructions reference NFPA-54, National Fuel
Gas Code for garage installation procedures.
Question:
Answer:
Question:
Answer:
Since this section limits location of furnaces in a garage, can a wood stove or other
space heater be located in a garage?
Not unless listed for such use. See s. Comm 23.045(2)(b).
Can a furnace be located in an attic?
Yes, if within the manufacturer's listing requirements. The following UDC
requirements and typical manufacturer's requirements would usually apply:
-
Provide attic access opening large enough for the appliance.
Provide combustion air per s. Comm 23.06.
Maintain manufacturer's and UDC clearances to combustibles and clearances for
servicing.
Provide lighting for servicing the appliance.
Provide a solid walkway to the appliance and solid platform under and around
the appliance for servicing.
The attic framing must be designed to support the furnace and servicing loads.
Isolate the appliance from any loose insulation that could enter the combustion
chamber.
Isolate the appliance from any drafts caused by power attic venting of the attic.
2009-23-3
23.045
Also, the furnace must be able to withstand freezing temperatures which may
adversely affect condensing-type furnaces.
23.045 Solid-Fuel-Burning Appliances
Effective February 1, 1989, solid-fuel-burning appliances had to be tested, listed and labeled by
an accepted testing agency. (See s. Comm 21.32 commentary for approved agencies.)
At the time the Dwelling Code was first written (1980), nationally recognized standards on
solid-fuel-type appliances were not available. Since that time, Underwriters' Laboratories have
developed standards for testing and listing solid-fuel- burning appliances. Most models on the
market are now tested, listed and labeled by approved independent agencies. When a specific
installation instruction approved by the testing/listing agency is more or less stringent than
s. Comm 23.045, then the listing agencies instructions govern.
23.045(3)(b) Co-venting of Solid-Fuel Appliances
Note that this section does not allow co-venting of solid-fuel appliances. Each fireplace,
woodstove, or other solid-fuel appliance must be vented to its own flue.
23.045(4) Chimney Connectors
Question: Does a solid fuel appliance in front of an existing fireplace opening require a
chimney connector?
Answer:
Usually, for proper operation, a smokepipe is needed from the appliance outlet to
the opening of the actual chimney flue per its listing. Additionally, a factory-built
fireplace's listing must be compatible for such an alteration.
23.045(6) Appliance Clearances
The requirement for proper clearances in this section refers to clearances to combustibles. It
should be remembered that an appliance still needs to comply with s. Comm 23.045(2) for the
proper servicing clearances.
A wood-frame wall with gypsum board or plaster finish is still considered a combustible wall for
determining appliance and smokepipe clearances. Heat is readily conducted to the studs
underlying the gypsum board. Over a period of time, the ignition temperature of the wood
decreases as it is dried out and chemically changed. Noncombustible surface protection is only
effective if there is at least a 1-inch air space between it and the combustible construction.
23.045(10) Combination Appliances
Note that this section requires combination appliances or dual-fuel appliances to be listed for the
combination use. If allowed by the listing, the units may be vented by the same flue.
Table 23.045-C specifies the floor mounts for solid-fuel-burning appliances.
23.06 Combustion Air for Wood Stoves
2009-23-4
23.06
Question:
Answer:
Comm 23.06(2). How do I calculate if a wood stove needs outside combustion air
because of small room size?
If the appliance is listed, then an hourly input rating is given and the calculation is
straightforward. An unlisted appliance's hourly input BTU rating can be figured on
the following basis:
BTU input = C x 60% (% firebox fill) x 40 lbs. wood x 8600 BTU x 1 fireboxfull
hr.
cu. ft.
lb. wood
2 hrs.
= 103,200 BTU/HR x C
cu. ft.
where: C = firebox capacity (cu. ft.) = l x w x h
= product of inside firebox dimensions in feet.
23.06 Combustion Air
The code offers several methods to supply adequate combustion air. Below is a highlighted
listing of the options. Also see the optional Makeup and Combustion Air Worksheet at the end
of this chapter.
Method 1. Inside Air (Discontinuous Vapor Retarder) [23.06(3)]: Allows combustion air to
be drawn from an inside space if the building has a discontinuous vapor barrier, as is permitted at
boxsills or below grade walls by s. 22.38(2)(c). The space shall provide a room volume of at
least 50 cubic feet per 1000 btu/hr combined input rating of all open combustion appliances in
that space. An inside space may include several rooms if connected with high and low openings,
with each opening providing one square inch of clear opening per 1000 btu/hr input rating, but
not less than 100 square inches each.
Method 2. Inside & Outdoor Air (Continuous Vapor Retarder) [23.06(4)(d)]: If a building
has a continuous vapor barrier, and therefore cannot use the method of 23.06(3) of taking all air
from inside, but does have a room volume of at least 50 cubic feet per 1000 btu/hr combined
input rating of all open combustion appliances in that space, then it can use a method of
supplementing the inside air with outside air. It shall be via a single, direct or ducted, exterior,
high opening, sized at one square inch per 5,000 btu/hr combined input rating.
Method 3. Single Outdoor Opening (Gas Appliances Only) [23.06(4)(c)]: If serving only gas
appliances, then from outdoors via a single, direct or ducted, exterior, high opening sized at one
square inch per 3,000 btu/hr combined input rating, but not less than the combined cross
sectional areas of the appliance flue collars or draft hood outlets in that space.
Method 4. Prorated Inside Air Credit Plus Outdoor Air [23.06(2)(d)]: For method 1, per
current national standards [2006 NFPA 54-9.3.4], we will also allow a combination of drawing
inside and outside combustion air, unless prohibited by the appliance manufacturer. This is done
by taking a pro-rated credit for an inside space that partially meets method 1, and then making up
the difference by pro-rating the outside combustion air otherwise required by Method 5
[23.06(4)(c)]. Example: If the inside space provides only 25 cubic feet per 1,000 btus, or half of
2009-23-5
23.06
the size required by method 1, then the additional direct or ducted outside combustion air, as
calculated by method 5 can be reduced by one half.
Method 5. Two Outdoor Openings [23.06(4)(b)]: From outdoors via high and low direct or
vertically ducted exterior openings, each sized at one square inch per 4,000 btu/hr combined
input rating or via horizontally ducted openings, each sized at one square inch per 2,000 btu/hr
combined input rating.
EXAMPLE:
1.
Determine if the space in which the heating appliances are located is large enough to supply
combustion air by itself per Method 1 pers. Comm 23.06(3).
a.
The plans indicate a utility room will be constructed which houses a:
(1) Gas-fired furnace (100,000 BTU input).
(2) Gas-fired water heater (33,000 BTU input).
b.
The utility room size is approximately 12 ft. long by 5.5 ft. wide. This is 66 sq. ft. in
area. The rest of the basement is 934 sq ft. in area.
The "Typical Section" drawing shows the room height to be 7 ft. 6 in. plus the depth
of the floor joists 9 1/4 in. Therefore, the height then becomes 8.27 ft. The section
also indicates that the vapor retarder is omitted on the boxsill, so s. Comm 23.06(3)
may be used.
The volume of the room equals 66 sq. ft. times 8.27 ft. or 545 cu. ft.
c.
The minimum room volume on the basis of the equation in s. Comm 23.06(3) is:
Volume = 100,000 BTU furnace + 33,000 BTU water heater x 50 cu ft = 6650 cu. ft.
1,000
Since the 545 cu. ft. is smaller than 6650 cu. ft., the utility room is too small and
another method of supplying combustion air must be used.
2.
Try Method 1 again, but draw combustion air from the whole basement via openings in the
utility room walls.
a.
The volume of the room equals 1000 sq. ft. times 8.27 ft. or 8270 cu. ft. which
satisfies the calculated required volume of 6650 cu ft above.
b.
Two openings are required (high and low), each sized as follows:
Opening Area = (100,000 BTU + 33,000 BTU) = 133 sq. in.
1,000
2009-23-6
23.08(1)
c.
This also satisfies the requirement for a minimum 100 sq in openings. (Two 1-sq. ft.
= 144 sq.in. openings would suffice.)
OR
3.
Try Method 3 per s. Comm 23.06(4)(c) single outdoor opening between the utility room
and the exterior. Since the appliances are all gas-fired, this method may be used. (We
could take a prorated credit per Method 3 of s. Comm 23.06(2)(d) for the utility room, but
because of it smallness, we will not bother in this example.)
a.
The minimum size of the single opening is determined as follows:
Opening Area = 133,000 BTU = 44 sq. in.
3,000
b.
An 8" round duct, which provides 50 sq in, would satisfy this. However, you must
also check that the combined flue collar areas of the appliances would be met:
The water heater has a 3" diameter collar which is 3.14(1.52) = 7sq in. in area.
The furnace has a 6" diameter collar which is 3.14(32) = 28 sq in. in area.
The combined area is 7 sq in + 28 sq in = 35 sq in - OK
c.
Consideration should be given to the blocking effect of screens and louvers in air
intake openings. Assuming 1/8" screen, multiply the 50 sq in of the 8" diameter duct
by 0.8 to arrive at 40 sq. in., which is too small and must have a transition to
something like a 8” x 8” square termination of steel louver [thus 48 in2 = 64 in2 x 0.75
louver factor per Comm 23.06(5)(c)] which still satisfies the requirement.
Subchapter IV  Delivery Systems
23.07 Duct Sizing
Table 23.07 sets minimum and maximum air velocities in ducts. Meeting minimum duct sizes
reduces air noise, occupant discomfort and fan inefficiencies. Meeting maximum duct sizes
economizes on materials, provides adequate air throw at outlets and may help fan efficiency.
See the commentary under 23.02 for an example of duct sizing calculation.
23.08(1) Ducts Used for Other Purposes
Question: Can electrical, telephone or cable TV wiring be run through air return or supply
ducts? Can supply ducts be run through air return ducts or joist spaces used as
returns?
Answer:
No, with three exceptions per National Electrical Code 300-22:
- Teflon-insulated wiring.
- Metal enclosed wiring.
- Romex wiring run perpendicularly to the length of a joist or stud space used as
a return air plenum.
2009-23-7
23.08(4)
The department will also allow water and waste piping run perpendicularly through
a duct if no pipe joints or cleanouts are within the duct. All penetrations have to be
sealed to maintain duct pressures and prevent air leakage. In addition the size of
the penetrating utility through the duct can NOT effect the velocity or capacity of
the duct to transmit the required air volume of the duct.
23.08(4) Underground Ducts
Also applicable to underground ducts is s. Comm 22.42 which requires R-8 insulation. The
more restrictive requirement controls.
23.08(7) Duct Support
Table 23.08-B was revised in 2009 to clarify the support of rigid ducts, including hanger options.
Question:
Answer:
Is there a maximum length of “flex-duct” that is allowed by the Code?
No, many people feel that since the Commercial Code limited duct length, the UDC
also should. There is no maximum length in the code; however, you must not
exceed the static pressure loss in Table 23.07 for air distribution systems.
Therefore, from a practical standpoint, flex-ducts will need to be less than 10-14
feet. In no case shall the minimum/maximum velocities or the maximum static
pressures be exceeded. Also note that there is a listing [and price] difference
between flex-duct and flex-connector, which are tested to different standards and
have different material limitations. For example the current commercial code does
not limit flex-duct length, however flex-connector does limit installed length at 14’.
For exhaust fans, it may be necessary to increase the fan capacity if the static
pressure is excessive due to a restrictive duct system. This is not to say that
adequate support of flex-duct or flex-connectors should be ignored, as the listing
for these products do have maximum bend radius and acceptable dip limitations.
23.09(1) Volume and Backdraft Dampers
Register dampers do not satisfy the requirement for volume duct dampers due to their looseness.
If duct volume dampers will be concealed behind finish materials, access panels shall be
provided to allow future adjustment. Alternatively, dampers may be placed behind registers,
which could be removed for future access to the dampers. This is now a requirement listed in
Comm 23.09(1)(b) to have access to the dampers for adjustment at later times.
23.09(2)(b) Return Air Openings
Question: Is it necessary to have a return air opening in each room that has a supply air
opening?
Answer:
No. If doors are undercut or other air transfer means are provided, it would not be
necessary to have a return air opening in each room. However, the air must at least
be transferred to a return duct serving the same floor level.
2009-23-8
23.11(1)
Question:
Answer:
In a two-story house, may a return air grille, at the base of the stairs to the second
floor, serve the second floor? (Can the stairway serve as a return air system?)
No. Per this code section there must be return grilles located on both floors.
23.10(1) Solar System Piping
Question: Can PVC (plastic) piping be used in a solar wet-heat system?
Answer:
Section Comm 23.10 addresses the subject of piping for wet-heating systems.
However, this section does not speak specifically to the kind of piping materials. It
only says that the material shall accomplish the calculated results without stress or
other detriment.
This section is also supplemented by s. Comm 71.25, Liquid Systems, of the Solar
Energy Systems Code which became effective July 1, 1986. The Solar Energy
Systems Code includes voluntary construction quality standards for solar collectors
and their supporting mechanical systems.
Section Comm 71.25 does allow plastic piping for some systems if the material
meets s. Comm 84.30 of the Plumbing Code.
Subchapter V  Chimneys and Vents
23.11(1) Summary of Common Vent and Chimney Types.
Classification
Other names
Cont. oF
Max. oF
Use
1. Single-wall
metal pipe
2. BW vent
3. B vent
Class C
--
--
Only as connector in residence
-Gas vent
550o
470o
---
Wall furnace (2”x4” wall)
Listed gas appliance with hood
4. L vent
5. Residential type
factory-built
chimney
a. Standard
Oil vent
Class A
All-fuel
Solid-fuel
Metal Chimney
570o
--
Gas or oil appliance per listing
1000o
1700o
1000o
2100o
--
(1000o)
1800o
--
--
--
b. HT (high
temperature)
6. Masonry
chimney with liner
7. Factory-built
fireplace and
chimney package
23.11(1) Power Venters
2009-23-9
Gas, oil and solid fuel
appliances
except
closedchamber solid fuel appliances
Includes closed chamber solidfuel appliances
Includes closed chamber solidfuel appliances
Per listing
Clearance
Per Comm 23.045
and 23.15
Per listing
B-1” to B-3”
B-2”x 4”, B-2”x 6”
L-1” to L-3”
1” – 2”
1” – 2”
1” – 2”
21.30(9)
Per listing
23.11(2)(b)
Question:
Answer:
Can power-vented appliances be used?
Yes. There are two types of power-vented appliances. One type is designed,
manufactured and listed as a unit. These are installed per their listing.
The second type is an add-on power venter designed and manufactured by a
manufacturer other than the appliance manufacturer. These units must either be
tested and listed for connection to specific appliance types.
Co-venting with either type must be done strictly per their listing because of
possible backdrafting and variable pressure conditions.
23.11(2)(b) Horizontal Vent Termination
Question: What is required for vent sizing when multiple appliances share a common vent and
equipment is changed or replaced?
Answer:
Gas vents are to be sized for the appliances currently connected to them.
Therefore, if the new equipment is either larger or smaller, the common vent may
have to be altered in size. This applies replacement equipment.
23.13 Physical Guarding of Chimneys and Vents
Question: Does an accessible chimney or vent need to be guarded against physical damage
when located in a space like a garage?
Answer:
Yes, normally a metal chimney usually does require to be guarded as part of its
listing. A metal vent may require guarding as part of its listing.
23.14(2) Dryer Venting
Question: May plastic vent pipe or flex-vent be used for clothes dryers?
Answer:
Probably not. Comm 23.14 (2) requires gas-fired clothes dryers to be vented to the
exterior with metal vent pipe. If the vent piping is concealed, then it shall be rigid
metal. Most manufacturers of even electric clothes dryers also recommend metallic
vents; however, some still allow plastic vents to be used.. Due to various safety and
fire hazards, the department recommends metal for all dryers that way if equipment
is changed out later to a gas dryer it would still be compliant.
2009-23-10
23.16(1)
Exit Terminals of Mechanical Draft and Direct-Vent Venting Systems.
Above diagram is gas vent terminal clearances from the Appendix of NFPA 54 standard.
Subchapter VI  Fuel Supply Systems
23.16(1) LP Gas Storage Tanks
Section Comm 23.16(1) states that LP gas tanks are subject to Ch. Comm 40, LP Gas Code.
That Comm 40 adopts NFPA 58 – 2004, Standard for the Storage and Handling of Liquefied
Petroleum Gases, which is summarized below. (Piping after the first stage regulator, with some
exceptions, is subject to NFPA 54, National Fuel Gas Code which is adopted by s. Comm 20.24).
We recommend you purchase the actual codes from NFPA at address shown in Table 20.24-10.
The following NFPA 58 and Comm sections summarize this section.
NFPA 58
Comm
40.43
Installer of a tank or tanks of 125 gallon or larger capacity shall
have certificate of installation form SBD 9656 and if over 2000
gallons shall notify the local fire department within 10 days.
[6.3.1]
[6.2.1]
See attached excerpted table and figures for minimum distances
between tanks and nearest other tank, important building or
adjoining property line.
23.16(1)(b)
No LP tanks inside dwellings.
2009-23-11
23.16(1)
[6.4.5.2]
[6.6.3.1]
Loose or piled combustible material and weeds not permitted
within 10 feet of tank.
23.16(1)(c)
Tanks to have welded steel supports and to be installed on
concrete pads or foundations.
[6.4.5.3]
No barriers around tank to trap leaked gas or to impede
firefighting.
[6.6.1.2]
Tank protected against damage by vehicles where likely.
(Four-foot tall concrete filled 6-inch steel posts are acceptable.)
[6.6.1.4]
Tanks to be properly painted.
[6.7.4.3]
First stage regulators to be as close as possible to the container
and outside of buildings.
[6.7.2.10]
Install first stage regulator downstream of tank shutoff valve.
[6.7.4.4]
Regulators to be securely anchored. Regulator outlet to be
protected to prevent entry of ice, snow or debris.
[6.7.4.5]
Regulator outlet to at least 3 feet horizontally away from any
building opening below the level of such outlet.
[6.7.4.6]
Min. 5' between pressure regulator and sources of ignition.
2009-23-12
23.16(1)
Figures below are from Appendix of NFPA 58-2004 standard.
2009-23-13
23.16(2)
23.16(2) Oil Storage Tanks
Section Comm 23.16(2) states that oil tanks are regulated by Comm 10, Flammable and
Combustible Liquids Code, which covers oil equipment and is summarized below:
Comm 10 & NFPA 31
Ch. Comm 10 adopts NFPA 31-2006, Standard for the Installation of Oil-Burning Equipment,
for tank requirements, which are summarized below for inside tanks Consult the code and
standard for further details.
4.3.1
7.5.8
7.5.9(1)
7.5.9(2)
7.5.11
7.5.11.2
7.5.11
7.5.12
7.5.14
8.2.1
8.3.2(1)
8.3.4
"
8.7.1
8.7.3
8.7.5
8.7.6
8.7.5.1
8.7.11
8.8.3
8.9.1
Tank normally located in lowest building level
Minimum 5' between tank and any source of heat.
Tank pitched 1/4" per foot to outlet.
Shutoff required at outlet of tank.
Both fill pipe and vent pipe installed on tank.
Vent pipe larger than largest withdraw or fill pipe or 1¼” minimum diameter.
Fill pipe and vent pipe to terminate outside.
Gauging device required on tank.
Tanks provided with rigid non-combustible supports
Piping to be metallic.
Fill pipe terminates at least 2' from any building opening at same or lower level.
Metal cover required on fill pipe.
Oil fill pipe to be identified.
Vent piping pitched to tank.
Vent pipe protected from physical damage.
Vent pipe to terminate at least 2' from any building opening.
Weatherproof hood required on vent termination.
Vent to terminate above snow or ice level
Vent to terminate at least 5' from any air inlet or flue gas outlet of any
appliance.
Gauge to visually or audibly tell tank filler when tank is full.
Piping to be tested.
23.16(2) Gas Piping Systems
This National Fire Protection Association Standard (NFPA) Standard 54 – 2006 is adopted by the
code for gas piping installation only. The requirements of the National Fuel Gas Code are
summarized below.
Question:
Answer:
Is copper piping for natural gas permitted within a dwelling?
Yes, if, per s. 5.6.2.3 of NFPA 54, there are no more than 0.3 grains of hydrogen
sulfide per 100 cubic feet of gas. To this department's knowledge, all gas delivered
to Wisconsin meets this limit. Installations conforming with NFPA-54 are
acceptable and comply with the UDC. Municipalities or local utilities may not
require the use of only black iron pipe if the installation complies.
2009-23-14
23.16(2)
NFPA 54-2006
Part 1
General
1.1.1.1
Code applies from point of delivery to gas utilization device for
both natural and LP gases.
["Piping" includes pipe (rigid) and tubing (flexible).]
Part 5
Design, Materials and Components
5.4.1
Piping sized to provide an adequate supply of gas - see
following tables.
5.6.2
Acceptable pipe - steel (black or galvanized), wrought iron,
copper*, brass*, aluminum alloy (aboveground interior only).
5.6.3
Acceptable tubing - copper* (Type K or L), aluminum alloy
(aboveground interior only), steel.
*Max. 0.3 grains of hydrogen sulfide/100 ft.3 (Wisc. okay).
5.6.4.1
Plastic pipe and tubing acceptable for underground exterior
uses only. (Plastic LP gas piping per NFPA 58.)
5.6.8
Acceptable joints and fittings.
5.6.8.1
5.6.8.2
- Pipe - threaded, flanged, brazed, welded, flared (nonferrous).
- Tubing - AGA approved tubing fittings, brazed (1000 DF
min., no phosphorous), flared.
5.6.7.4
Pipe dope or tape on threaded joints unless not required by
fitting manufacturer.
5.7.2.3
No sources of ignition (electrical equipment, flue gas exhausts,
combustion air intakes, etc.) within 3 feet of gas meters.
5.8.5.1(1)
Interior pressure regulators to be vented outside or ventlimited.
5.8.5.2
Per NFPA 58, s. 6.7.4.5, LP gas regulator to be vented so outlet
is no less than 3 feet horizontally away from any building
opening below the outlet.
5.12
Listed shutoff valves
2009-23-15
23.16(2)
Part 7
Installation
7.1.2.1
Underground piping to have 18" cover, 12" if not subject to
hazard.
7.1.5
Underground piping to be sleeved and caulked at foundation
entrance.
7.1.6.1
Piping underneath buildings in a conduit vented to outside and
sealed at building entrance.
7.2.1
Aboveground exterior piping securely supported and coated or
wrapped at foundation entrance.
7.2.5
Piping okay in accessible above-ceiling spaces, including
plenums, but no valves allowed.
7.2.5
Piping not allowed in:
- Circulating air ducts.
- Clothes chute.
- Chimney or gas vent.
- Dumbwaiter or elevator shaft.
- Ventilating duct, but okay in combustion air duct.
7.2.6.2
Piping support on center spacing:
- Pipe – ½" - 6', - ¾" or 1" - 8'; - 1-¼" - 10'
- Tubing – ½ " - 4'; - 5/8" or 3/4" - 6'; - 7/8" or 1" - 8'
Vertical piping must be supported a minimum at each floor.
7.3.2
Following fittings not allowed in concealed piping:
- Unions.
- Tubing fittings, except by brazed fittings.
- Compression couplings made by combination of fittings.
- Right-and-left couplings.
- Bushings.
- Swing joints.
7.3.2(4)
Reconnection into existing concealed piping:
- In pipe by welding, flanges, or ground joint union with
center punched nut to prevent loosening by vibration.
- Not allowed in tubing.
7.3.3
Piping not allowed in solid (such as concrete) partitions.
2009-23-16
23.16(2)
Part 8
7.3.4
Tubing, if not rigidly secured, can be concealed in partitions if
protected against nail penetration with 0.05” thick or 16 gauge
sheet metal or equivalent at penetrations of studs, plates and
firestops and 4" beyond.(Note that per CSST standard,
protection is for 5" beyond member.)
7.3.5.2
Piping in slab floors to be laid in channels with removable
covers or must have minimum 1-1/2” concrete around them.
7.7.1
7.7.1.2
7.7.1.4
7.7.1.5
7.7.2.1
Outlets:
- Not allowed behind doors.
- Unthreaded portion of pipe to protrude at least 1" out of
walls and ceilings and
- 2" above floors (quick connect devices exempt).
- To be capped when not used.
7.9.1
Gas shutoff valve required upstream of pressure regulator.
7.9.2.2
Exterior shutoff valve required at each building served.
7.13.1
Piping to be electrically continuous and bonded to any
grounding electrode (may use equipment grounding conductor)
but not to be used as a grounding electrode.
Testing
Installer shall test system at the greater of 3 psi or 1-1/2 times working pressure for at least 10
minutes prior to putting in service. If pressure drop is detected, then joints shall be tested with
gas detector, soap and water or equivalent nonflammable solution
Part 9
Equipment (Connections to Piping)
9.1.17
Equipment supported not to strain piping or connections.
9.6.1
9.6.1(1)
9.6.1(2)
9.6.1(3)
9.6.1(4)
9.6.1(6)
Equipment connectors allowed:
- Rigid pipe.
- Tubing.
- Listed connectors (in same room only and where not subject
to damage).
- Listed hose connector (outdoors only).
- Listed nonmetallic gas hose connectors.
9.6.4
9.6.4.1
9.6.4.1(1)
Equipment shutoffs:
- Within 6' of appliance.
- Upstream of connector.
2009-23-17
23.16(2)
9.6.4.1(1)
9.6.4.1(2)
- Union downstream of valve.
- Decorative appliances in fireplace, if listed for that use.
9.6.7
Sediment trap required at all appliances except lights, ranges,
dryers, gas fireplaces and outdoor grilles.
9.6.8
Piping not to interfere with appliance servicing (24" away from
access panels).
Sizing Gas Piping
1.
Determine appliance gas demand from name plate or the following Table C-1.
-
Natural Gas - Use cubic feet per hour which equals BTU input divided by average BTU
heating value per cubic foot of gas (typically 1000 BTU per cubic foot).
-
LP Gas - Use BTU input.
2.
Measure the length of piping from point of delivery to the most remote outlet in the
building.
3.
Using the appropriate table, select the column showing the measured length or next longer
length. This is the only column that will be used for the whole system.
4.
In the selected column, find the gas demand, or next higher demand, of the most remote
outlet and piping section.
5.
Opposite this demand figure, find the correct gas piping size in the far left column.
6.
Proceed in a similar manner for each outlet and each section of gas piping using the same
column. For each piping section, determine the total gas demand supplied by that section.
2009-23-18
23.16(2)
Table C-1
Approximate Gas Input for Typical Appliances
Appliance
Input
BTU per hour
(Approximate)
65,000
25,000
40,000
Range, Free Standing, Domestic
Built-In Oven or Broiler Unit, Domestic
Built-In Top Unit, Domestic
Water Heater, Automatic Storage
30 to 40 Gallon Tank
Water Heater, Automatic Storage
50 Gallon Tank
Water Heater, Automatic Instantaneous
(2 Gallons Per Minute
Capacity (4 Gallons Per Minute
(6 Gallons Per Minute
Water Heater, Domestic, Circulating or Side-Arm
Refrigerator
Clothes Dryer, Type 1 (Domestic)
Gas Light
Incinerator, Domestic
35,000
50,000
142,800
285,000
428,400
35,000
3,000
35,000
2,500
35,000
For specific appliances or appliances not shown above, the input should be determined from the
manufacturer's rating.
Table C-17
Maximum Capacity of Semi-Rigid Tubing in Thousands
of BTU per Hour of Undiluted Liquefied Petroleum Gases
(at 11 Inches Water Column Inlet Pressure)
(Based on a Pressure Drop of 0.5 Inch Water Column)
Outside
Diameter,
Inch
10
3/8
39
1/2
92
5/8
199
3/4
329
7/8
501
Length of Tubing, Feet
20
26
62
131
216
346
30
21
50
107
181
277
40
19
41
90
145
233
50
-37
79
131
198
2009-23-19
60
-35
72
121
187
70
-31
67
112
164
80
-29
62
104
155
90
-27
59
95
146
100
-26
55
90
138
Table C-4
Maximum Capacity of Pipe in Cubic Feet of Gas per
Hour for Gas Pressures of 0.5 Psig or Less and a
Pressure Drop of 0.5 Inch Water Column
(Based on a 0.60 Specific Gravity Gas)
Nominal
Iron Pipe
Size,
Inches
Internal
Diamet
er,
Inches
Length of Pipe, Feet
10
20
30
40
50
60
70
80
90
100
125
150
175
200
1/4
0.364
43
29
24
20
18
16
15
14
13
12
11
10
9
8
3/8
0.493
95
65
52
45
40
36
33
31
29
27
24
22
20
19
1/2
0.622
175
120
97
82
73
66
61
57
53
50
44
40
37
35
3/4
0.824
360
250
200
170
151
138
125
118
110
103
93
84
77
72
1
1.049
680
465
375
320
285
260
240
220
205
195
175
160
145
135
1-1/4
1.380
1,400
950
770
660
580
530
490
460
430
400
360
325
300
280
1-1/2
1.610
2,100
1,460
1,180
990
900
810
750
690
650
620
550
500
460
430
2
2.067
3,950
2,750
2,200
1,900 1,680
1,520
1,400
1,300
1,220
1,150
1,020
950
850
800
2-1/2
2.469
6,300
4,350
3,520
3,000 2,650
2,400
2,250
2,050
1,950
1,850
1,650
1,500
1,370
1,280
3
3.068
11,000 7,700
6,250
5,300 4,750
4,300
3,900
3,700
3,450
3,250
2,950
2,650
2,450
2,280
4
4.026
23,000 15,800 12,800 10,900 9,700
8,800
8,100
7,500
7,200
6,700
6,000
5,500
5,000
4,600
2009-23-20
23.16(2)
2009-23-21
Table C-6
Maximum Capacity of Semi-Rigid Tubing in Cubic Feet
of Gas per Hour for Gas Pressures of 0.5 Psig or Less
and a Pressure Drop of 0.5 Inch Water Column
(Based on a 0.60 Specific Gravity Gas)
Outside
Diameter,
Inch
10
20
30
40
50
60
70
80
90
100
125
150
175
200
3/8
27
18
15
13
11
10
9
9
8
8
7
6
6
5
1/2
56
38
31
26
23
21
19
18
17
16
14
13
12
11
5/8
113
78
62
53
47
43
39
37
34
33
29
26
24
22
3/4
197
136
109
93
83
75
69
64
60
57
50
46
42
39
7/8
280
193
155
132
117
106
98
91
85
81
71
65
60
55
Length of Tubing, Feet
Table C-16
Maximum Capacity of Pipe in Thousands of BTU per Hour
of Undiluted Liquefied Petroleum Gases (at 11 Inches Water Column Inlet Pressure)
(Based on a Pressure Drop of 0.5 Inch Water Column)
Nominal
Iron Pipe
Size,
Inches
1/2
3/4
1
1 1/4
1 1/2
2
Length of Pipe, Feet
10
275
567
1071
2205
3307
6221
20
189
393
732
1496
2299
4331
30
152
315
590
1212
1858
3465
40
129
267
504
1039
1559
2992
50
114
237
448
913
1417
2646
60
103
217
409
834
1275
2394
2009-23-22
70
96
196
378
771
1181
2205
80
89
185
346
724
1086
2047
90
83
173
322
677
1023
1,921
100
78
162
307
630
976
1811
125
69
146
275
567
866
1606
150
63
132
252
511
787
1496
23.18
23.16(4) Shutoff Valves
Question: Can a water-type valve be used as a manual gas shutoff valve?
Answer:
No. Gas shutoff valves must be approved by AGA or UL for such use. Their
approval will be indicated on the valve.
Question:
Answer:
Is a manual shutoff device acceptable on a gas fireplace starter?
Yes. (Gas log systems shall be installed per their listing.)
Subchapter VII  Equipment Location and Operation
23.17(2) Equipment Location
Section Comm 23.17(2) requires indoor equipment to be installed with a minimum of 24 inches
clearance for service. This service clearance is only required on the face(s) of the equipment
with service panels. Otherwise, lesser clearances as allowed by the listing are acceptable.
23.18 Equipment Operation
Question:
Balancing and testing of every HVAC system is required by Comm 23.18(2), can the UDC inspector ask for a copy of that balancing report or pressure test?
Answer:
Yes, at the final inspection a copy of that documentation should be found on site.
Note that the duct sealing requirements of Comm 22.43 may be related to the
testing of the ventilating system, as are toilet exhausts and make-up air supplied.
Some inspectors or owners may wish to know what sort of items should this testing and/or
balancing report have included. Guidance from commercial building code Comm 64.0313 on
this issue could help to be used as reference in order determine what information is required to
be addressed and the means by which the information may be recorded. Included below is the
note from that code section:
Note: National Environmental Balancing Bureau (NEBB) Procedural Standards, the
Associated Air Balance Council (AABC) National Standards, the Sheet Metal and Air
Conditioning Contractors National Association, Inc (SMACNA) as issued in "HVAC
SYSTEMS Testing, Adjusting & Balancing" or equivalent balancing procedures are
acceptable to the department.
It is known SMACNA even provides general forms for use in balancing. Some of the forms in
SMACNA are impractical for use in residences since the systems are so simple, but at least
SMACNA does provide information on what information is required to be addressed, and the
means by which the information may be recorded for future review by the contractor who
balanced the system, the owner, as well as the UDC inspector &/or Dept. representative should
there be any questions as to the performance of the HVAC system at a future time.
2009-23-23
23.18
Summary of Rules for Water Heaters Used for Space Heating
1/12/09
Note: Chs. Comm 20-25 apply to one- and two-family dwellings built since 1980, Chs. Comm
60-66 apply to commercial and multi-family dwellings. Chs Comm 82-87 apply to all buildings.
•
•
•
•
•
•
•
Listing: Per ss. Comm 23.04(5) and Comm 64.0301(3), water heaters used for space
heating need to be listed for such use. The data plate shall indicate that the unit can be used
for space heating. Note in Comm 23.04(5)(a) specifies that they be listed per ANSI Z21.10.1
or ANSI 21.10.3 [for inputs < 75 MBH or over 75 MBH respectively]. The typical listing is
for dual use, which means that in addition to the heating use, it shall also be used for potable
use, which may be satisfied with at least one properly connected water fixture.
Alternatively, s. Comm 64.0301(3)(b) allows unlisted equipment if a standard is cited by the
manufacturer and then a Wisconsin engineer tests the appliance to it.
WI Boiler Code: This code does not require all water appliances used for space-heating to
be considered boilers and to comply with boiler standards.
Efficiency: Federal appliance efficiency standards have usurped our efficiency requirements
for smaller appliances for which they have developed a standard. They require that a
manufacturer meet the standard applicable for the type of appliance that they market an
appliance as being classified. There is a federal standard for potable water heaters. There is
a federal standard for boilers, which would apply to water heaters used for space heating
only. There is only a federal standard for water heaters in general, not specifically dual-use
water heaters. We do not have an efficiency standard for dual-use water heaters in either
residential or commercial occupancies. There is NO state or local responsibility or authority
to enforce the federal rules.
Sizing: Per s. IECC Table 404.5.2 footnote h, for multi-family housing, a dual-use water
heater shall be sized by proportion for both uses with a maximum 1 hour potable water
recovery period at winter design temperature for space heating. Otherwise, for UDC
purposes, the appliance shall be sized and documented to provide sufficient heat.
Plumbing Code: Any equipment or piping that comes in contact with potable water must
meet the potable water plumbing materials standards. (A WI Plumbing Products Approval is
not required anymore.) The installation of the system that comes in contact with the potable
water system must be installed by a properly credentialed plumber. A floor drain must be
provided for the water heater, if the water heater is installed on the lowest floor level. If a
heat exchanger is used and only food grade additives are used, it may be a single-wall heat
exchanger. If non-food grade additives are used, then the heat exchanger shall be a vented,
double wall heat exchanger as required by s. Comm 84.41(3)(d). The valving and safety
devices on the system must comply with the Plumbing Code.
Nonpotable piping: If the listing permits the installation of backflow prevention at the
water heater inlet or isolation of the water heater, then non-potable material potable water
materials may be used. Nonpotable, heat distribution piping standards are not specified in
either code.
Backflow Protection: If backflow protection is installed, then the buildings water system is
no longer available for expansion of the heated water. The temperature-pressure relief valve
must be selected in coordination with the backflow preventer. There needs to be an
2009-23-24
23.18
•
•
expansion tank or other expansion means provided. These items, if allowed, shall be
installed per the water heater's listing and Wisconsin plumbing code.
Isolated Water Heaters: If a water heater is installed with no connection to the potable
water system, then proper water expansion means shall be provided per the water heater's
listing.
Pipe Insulation - Per ss. Comm 22.44 and IECC 503.2.8, heating pipes shall be insulated to
minimum R-4 when passing through unheated spaces [unless IECC 403.3 with R-2 applies].
2009-23-25
23.18
Optional Uniform Dwelling Code (UDC) Makeup and Combustion Air Worksheet (1/12/09)
Project Address ___________________________ Completed by: _______________ Tel. ______________
Background: The UDC applies to all one and two family dwellings built since June 1, 1980. Section Comm 23.02
of the UDC requires that outside makeup air be supplied to balance mechanical exhaust ventilation, including
required bathroom fans, so that adequate air change occurs, without backdrafting of open combustion heating
appliances. Section Comm 23.06 of the UDC requires that adequate combustion air be supplied to heating
appliances for complete fuel combustion and flue gas venting purposes, which should minimize carbon monoxide
hazards. This worksheet demonstrates compliance with both requirements.
If your dwelling does not have any open combustion appliances, then you do not have any combustion air
requirements and, by code, can rely upon infiltration through building cracks for makeup air. Open combustion
appliances are those which use air from within the dwelling for combustion.
NOTES: Typical appliance values are given in the tables, however use actual values if known.
Round pipe has the following areas: 3" dia. pipe - 7 sq in, 4" - 12 sq in, 5" - 20 sq in, 6" - 28 sq in, 8" - 50 sq in,
10" - 79 sq in, 12" - 113 sq in.
Opening Restrictions: If louvers or screening is provided on an opening, then multiply its gross area by the
following factors to obtain the net area (alternatively, knowing the net area, divide to obtain the gross area): 1.0 for
1/4" hardware cloth, 0.8 for 1/8" screen, 0.75 for metal louvers, 0.5 for metal louvers and 1/8" screen, and 0.25 for
wood louvers [per Comm 23.06(5)(c)].
A. Makeup Air - Complete the following table for exhaust fans, but not recirculating, whole house fans, attic fans
or inlets of balanced ventilation systems.
Intermittent Exhaust Fans
Bathroom fan (min. 50 cfm)
Resid. kitchen range hood
Downdraft range exhaust
Electric clothes dryer
Gas clothes dryer
Typical Exhaust CFM
75
180
400
175
150
OR Actual CFM
Number
x
x
x
x
x
Total (cfm)
SubTotal
Intermittency Adjustment Factor X .40
Adjusted Total
Any constant exhaust fans without dedicated makeup air +
Net Grand Total Makeup Air Required
You can provide makeup air via the following methods (check appropriate boxes). Note that openings or ducts
shall be provided between the source of the makeup air and the exhaust fans.
Intake fans with a capacity equal to the Grand Total above. If ducts are connected to the fan, the fan
capacity shall be appropriately adjusted.
Openings to the outside, ducted to the return plenum of the furnace to provide tempering and distribution.
Multiply the Grand Total by the appropriate restriction factor for louvers or screening to obtain the gross
makeup air required:
_________(Net Grand Total Makeup Air Required) ÷ _______ (Opg Restr. Factor) = _________ (Adjusted
Makeup Air Reqd)
The calculated capacity for round intake duct is: 3" - 38 cfm; 4" - 69 cfm; 6" - 157 cfm; 8" - 279 cfm (Circle
planned size)
2009-23-26
23.18
Section Comm 23.02(3)(a)2. requires outside makeup air openings to have shutoff means of automatic or gravity
dampering for periods when no makeup air is required. Because of this dampering requirement, you may not use
makeup air openings for combustion air openings, which are prohibited to have dampers.
B. Combustion Air (Note that appliance manufacturer requirements may be more restrictive.)
There are several methods of providing combustion air, of which you will choose one for each group of appliances
in a common space. First, complete the table for open combustion appliances on the next page to determine if
you can comply with method 1 or 2, below, which allows at least some inside combustion air. Otherwise, choose
another method from the next page.
1. Inside Air (Discontinuous Vapor Retarder): Allows combustion air to be drawn from an inside space if the
building has a discontinuous vapor barrier, as is permitted at box sills by s. 22.38(2)(c)2. The space shall
provide a room volume of at least 50 cubic feet per 1000 btu/hr combined input rating of all open combustion
appliances in that space. Room Interconnection: An inside space may include several rooms if connected
with high and low openings, with each opening providing one square inch of clear opening per 1,000 btu/hr
input rating, but not less than 100 square inches each. Remember to apply the above Opening Restriction
Factors for louvers on the openings.
Room Interconnection:
Net Sq. In Req'd at Input/1,000:
(Min. 100 in2) ÷ ____(Opg. Restr. Factor) = ______sq. in. each opg;
Appliance
Furnace
Appl.
Group
Number
Gas
Other
Gas or Oil Water heater
Typical
BTU/hr
Input
Actual
BTU/hr
Input
100,000
Total BTU/hr in
Each Numbered
Group of
Appliances That
Share a Space
Room or
Interconnected (per
Method 1)
Space
Volume
Room Volume
Divided by
[Total BTU/hr
in Room ÷
1,000]*
Appl. Group 1
50,000
Appl. Group 2
Gas clothes dryer
35,000
Gas fireplace
50,000
Gas range
Wood stove or fireplace
(Input per cu. ft. of firebox
capacity)
65,000
100,000
Appl. Group 3
*If any room, or interconnected group of rooms, provide less than 50 cu ft per 1,000 BTU/hr of all
appliances within, per the last column of the table, or the dwelling has a continuous vapor barrier, then
choose one of the appropriate methods below. Enter the appliance group number in front of the applicable
method. You can skip to Method 4 or 5 if the room is small and isolated.
2. Inside & Outdoor Air (Continuous Vapor Retarder): If dwelling has a continuous vapor barrier, and
therefore cannot use method 1 of taking all air from inside, but per the above table has a room volume of at
Appl
least
50 cubic feet per 1000 BTU/hr combined appliance input rating, then provide supplemental outside air
Group#
via a single, direct or ducted, exterior, high opening, sized at one square inch per 5,000 btu/hr combined input
______ rating.
Exterior Opening:
÷ ____(Opg. Restr. Factor) = ____sq. in.; Planned Opg. Dim.: ____
Net Sq. In. Required at Input/5,000:
2009-23-27
23.18
Room Interconnection:
Net sq. in. Req'd at Input/1,000:
(Min. 100 in2) ÷ ____(Opg. Restr. Factor) = _____sq. in. each opg;
3. Single Outdoor Opening (Gas Appliances Only): If serving only gas appliances, then provide outdoor air via a
single, direct or ducted, exterior, high opening sized at one square inch per 3,000 BTU/hr combined input
rating, but not smaller than the combined cross sectional areas of the appliance flue outlets in that space.
Appl
Group#
a. Sizes & areas of flues: ________________________________ Total flue area:
______
b. Net Sq. In. Required at Input/3,000:
sq in.
sq in..
Greater of a. or b.: _______ ÷ ______(Opg. Restr. Factor)= ________sq. in.; Planned Opg. Dim.: ________
4. Prorated Inside Air Credit Plus Outdoor Air: Calculate the pro-rated credit for an inside space that partially
meets method 1, and then make up the difference by pro-rating the outside combustion air otherwise required
Appl
by method 5. Example: If the inside space provides only 25 cubic feet per 1,000 BTU/hr (per last column of
Group#
table above), or half of the size required by method 1, then the additional direct or ducted outside combustion
air,
as calculated by method 5 can be reduced by one half.
______
Pro-rating credit: 100% - [ ________ (Actual room vol. per 1000 BTU/hr) x 2)] = __________
5. Two Outdoor Openings: Provide outdoor air via high and low, direct or vertically ducted, exterior openings,
each sized at one square inch per 4,000 BTU/hr combined input rating; or via horizontally ducted openings,
each
sized at one square inch per 2,000 BTU/hr combined input rating.
Appl
Direct
or Vertical Ducts: Sq In Required at Input/4,000:
sq in x
(Credit from 4.) =
sq in.
Group#
______
Horizontal Ducts: Sq In Required at Input/2,000:
sq in x
(Credit from 4.) =
sq in.
Net Sq. Inches Required: _______ ÷ ____(Opg. Restr. Factor) = ______sq. in.; Planned Opg. Dim.: ______
2009-23-28
Chapter Comm 24
ELECTRICAL STANDARDS
Electrical Standards
Electrical wiring in new homes shall comply with the most recent version of the Wisconsin
Administrative Electrical Code, ch. Comm 16.
Chapter Comm 16 adopts the current version of the National Electrical Code (NEC) standard by
reference subject to the changes, additions, or omissions specified in Comm 16 Subchapter III.
Electrical inspectors shall obtain a copy of Comm 16 in addition to the NEC.
(Many inspectors personally cross-reference Comm 16 modifications into their NEC code book
effectively merging the two codes into one working document.)
The NEC is generally revised every three years. Chapter Comm 16, in turn, adopts the most
recent version of the NEC. Wisconsin certified electrical inspectors are notified when the most
recent version of the NEC is, in fact, adopted and effective in Wisconsin.
2009-24-1
Chapter Comm 25
PLUMBING
Well Water Supply
Private well construction standards are regulated by the Department of Natural Resources
through Chapter NR 812. Some counties (zoning, health departments) may also be involved in
enforcement of well requirements.
Maximum Residential Water Heater Temperature Settings
Various state legislation regulates residential water heater settings. Although there are no
inspection responsibilities for inspectors, you may be interested in these requirements. They
require:
• Manufacturers to set water heater thermostats no higher than 125dF and to affix labels to
heaters warning of the dangers and costs of higher settings. (s. 134.81, Wis. Stats.)
• Gas or electric public utilities to send an annual notice to customers on the dangers and
costs of higher thermostat settings. (s. 196.373, Wis. Stats.)
• Landlords to set water heater thermostats no higher than 125°F (or at the minimum
setting if that is over 125°F) before any new tenant occupies the premises. (s.
704.06, Wis. Stats.)
For further information, contact the Wisconsin Department of Agriculture, Trade and Consumer
Protection, (608) 267-9512 or (800) 422-7128.
Section Comm 82.10 (2) of the Plumbing Code, referenced by s. Comm 25.01, requires that if a
dwelling is connected to a private on-site waste treatment system (POWTS) or public sewer, then
it shall be provided with a water closet, wash basin, kitchen sink and bathtub or shower. These
fixtures shall be piped with an adequate water supply. A non-water based alternative to the water
closet, such as a privy or composting or incinerating toilet may be installed per Ch. Comm 91,
Sanitation, if not prohibited by the county or municipality.
Unless required by the county or municipality, a dwelling not served by a POWTS or public
sewer does not require any plumbing fixtures. However, the dwelling shall be provided with an
adequate source of potable water. If not prohibited by the county or municipality, it may be
provided with an alternative non-water based toilet per Ch. Comm 91.
As before, any plumbing work done prior to legal occupancy, not including the installation of
alternative non-water based toilets, shall be done by licensed plumbers. After occupancy, any
plumbing work shall be done by licensed plumbers or the owner-occupant of a single-family
home. Local ordinances may require post-occupancy plumbing work to be done only by licensed
plumbers.
2009-25-1