Continuous Insulation for CodeCompliant, High-Performance Walls
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Polyisocyanurate Insulation Manufacturers
Association (PIMA)
Provider Number: G501
Continuous Insulation for Code-Compliant,
High-Performance Walls
Course Number: CICCHPWLV
Speaker Name/s
Date
Credit(s) earned on completion of
this course will be reported to AIA
CES for AIA members.
Certificates of Completion for both
AIA members and non-AIA
members are available upon
request.
This course is registered with AIA
CES for continuing professional
education. As such, it does not
include content that may be
deemed or construed to be an
approval or endorsement by the
AIA of any material of construction
or any method or manner of
handling, using, distributing, or
dealing in any material or product.
_______________________________________
Questions related to specific materials, methods,
and services will be addressed at the conclusion
of this presentation.
Copyright Materials
This presentation is protected by US and International Copyright laws.
Reproduction, distribution, display and use of the presentation without written
permission of the speaker is prohibited.
© PIMA 2012
Course
Description
This presentation provides a comprehensive overview of
the application of foam sheathing as continuous insulation.
The presentation will instruct attendees in five topic areas;
continuous insulation (CI), applications, energy code
compliance, building code compliance and installation
detailing. Attendees will gain a comprehensive
understanding of the use, properties and benefits of foam
sheathing as continuous insulation.
Learning
Objectives
At the end of this course, participants will be able to:
1. Define continuous insulation (CI), the role of CI and types and
properties.
2. Identify the applications of CI, including its use as exterior
insulation, water-resistive barrier (WRB), air barrier (AB) and
multi-functional (composite sheathing).
3. Understand energy code compliance, including prescriptive,
u-value and performance paths.
4. Understand building code compliance, including fire, structural
(bracing, wind pressure, cladding) and building science (WRB,
AB, vapor barrier [VR] – moisture control) considerations.
Topical Outline
• Topic #1 – Continuous Insulation
– Definition
– Role of Continuous Insulation
– Types and Properties
• Topic #2 – Applications
– Exterior Insulation
– Water-Resistive Barriers (WRB)
– Air Barriers (AB)
– Multi-functional
Topical Outline (cont’d)
• Topic #3 – Energy Code Compliance
– Prescriptive Path
– U-value Path
– Performance Path
• Topic #4 – Building Code Compliance
– Fire
– Structural
– Building Science
Topical Outline (cont’d)
• Topic #5 – Installation Detailing
Introduction
• Why learn about continuous insulation (CI)?
– Used since the early 1900s
– Used on low-slope commercial roofs for a long time
• Scope: CI wall applications only
Introduction
• About PIMA
– Represents polyiso insulation manufacturers and
industry suppliers
• Mission
– Unified voice for rigid polyiso industry
– Advocate for safe, cost-effective, sustainable and
energy-efficient construction
– Leadership, advocacy and education
• pima.org
Introduction – Polyiso
• Widely-used and cost-effective
• Responsible impact on the environment
• Closed-cell, rigid foam board insulation
– Offices
– Health facilities
– Retail and industrial manufacturing facilities
– Warehouses
– Educational institutions
Introduction – Polyiso
• High thermal performance
– Product of choice for energy-aware building owners,
homebuilders and consumers
Introduction – Polyiso
• Key attributes:
– Highest R-value per inch of thickness
– Moisture-resistant, water-repellent panel
– Resistant to solvents
– Excellent dimensional stability
– Superior fire performance
Introduction – Polyiso
• Key attributes of polyiso include:
– Service temperature: -75°F (-60°C)
to 225°F (107°C)
– Long-term R-value
– Recycled content
– Zero ozone depletion potential
– Virtually no global warming
potential
• pima.org
Topic #1 – Continuous Insulation
• Definition (ASHRAE 90.1)
Role of CI
Kinds of Continuous Insulation
• Rigid Foam Plastic Sheathing
– EPS, ASTM C578
– XPS, ASTM C578
– Polyiso, ASTM C1289
Kinds of Continuous Insulation
• Spray foam
– SPF
• Others
– Rock wool
– Fiberglass boards
– Fiberboard
CI has been in successful use
for more than half a century!
R-value per Inch
• Rigid foam plastic sheathing
– High R-value per inch
– Low cost
• Various ASTM “types”
• Successful use on roofs and walls
TABLE 1. Examples of Minimum R-Value Per Inch for Common Types
of Continuous Insulation (Foam Sheathing)
Continuous Insulation Material Type
R-value per Inch of Thickness
EPS (ASTM C578, Type II)
4.0
XPS (ASTM C578, Type X)
5.0
Polyiso (ASTM C1289, Type 1)
6.0
Water Resistance
• Stringent water absorption resistance
requirements
Table 1. Standard Test Methods and Criteria for Moisture Absorption
Resistance Characterization of Various Insulation Board Materials
Insulation Material Type
Polyiso (ASTM C1289)
Fiberboard (ASTM C208)
Maximum Moisture
Content
(% Volume Basis)
ASTM C 209
(2-hour Water
Immersion Test)
1-2%1
7-10%
1. Does not include facers; applies to polyiso core material only.
Water Resistance (Source: APA)
Moisture Sorption Comparison
Durability
• Polyiso sheathing
– Does not rot, decay or corrode
• Other wall sheathing
– Prone to moisture damage
Topic #2 – Applications of CI
• Exterior Insulation Residential
– Minimum R5 CI can be used for climate zones 4 Marine
and 5 and above in the 2009 IECC.
– Minimum R5 can be used for climate zones 3 and
above in the 2012 IECC.
• Exterior Insulation Commercial
– Minimum R3.8 CI can be used for all climate zones in
the 2012 IECC.
• Meets energy code R-values or U-values for walls
Applicable to Various Wall Types
CI Mitigates Thermal Bridging
• Continuous layer of thermal insulation
– Important for steel framing
– Effective insulating concrete/masonry walls
– Considered a “best practice” by building science
experts
– Avoid cold wall surfaces
Thermal Bridging
Creative CI detailing mitigates
this stud challenge
Applications of CI (cont’d)
• Air Barrier (AB)
– Most foam sheathing meets AB requirements
• Check with manufacturer
– Key to seal joints
– Ideal approach is dual air-barrier
Applications of CI (cont’d)
• Water-Resistive Barrier (WRB)
– Only applies to approved products
– Approved flashing tape required
– Quality installations = durable
• Rigorous code acceptance testing
• Very water- and air-infiltration resistant
WRB Installation
(NIST Net-Zero Energy House / BSC / ARES)
Building Science Corporation
Topic #3 – Energy Code Compliance
U.S. Climate Zones
Why Energy Conservation?
• Even small improvements can have a big impact
– Energy code improvements can break even mortgage
cost in 10 months
Why Energy Conservation?
Why Energy Conservation?
Three Basic Approaches for Insulating
Light-Frame Exterior Walls
1. Cavity insulation only
2. Cavity insulation + continuous insulation
3. Continuous insulation (CI) only
Prescriptive Compliance Path (Walls)
Continuous Insulation (CI)
Prescriptive path is based on nominal R-values of insulation,
not actual R-value of the assembly
Energy Code Compliance Equal to or Exceeded
Easier with Polyiso R-value of 6 per inch
U-factor Building Performance
Compliance Path
• Use this approach to:
– Explore alternatives to the prescriptive wall insulation
– More CI, less CI; More cavity, less cavity; etc.
• Must use code-compliant insulation materials
• Must substantiate U-value for assembly
• NOTE: U = 1/Ract ≠ 1/Rnom
U-factor Building Performance Path
(cont’d)
This table is for Residential Buildings
Building Performance Path
• Make full use of trade-offs or demonstrate
whole-building compliance
– Requires approved energy modeling
Topic #4 – Building Code Compliance –
Fire
• Fire safety requirements for foam sheathing
– IBC Chapter 26
– IRC Section R316
– Comprehensive and effective
Foam and OSB Comparison
Fire Performance Advantages
of Polyiso Sheathing
• Thermoset material
• Stays intact during fire exposure
• Remains in place during ASTM E84 tunnel testing
– Meets or exceeds flame spread ratings
Fire Performance Advantages
of Polyiso Sheathing
• Not all foam sheathing materials are equal
– Thermoplastic materials (e.g. polystyrene)
• Soften at 165°F
• Melt at approximately 200°F
• Drip and can continue to burn
Exterior Flame Spread
• NFPA 285 assembly testing
– Not required for Type V
construction and some 1-story
construction
– Not required for IRC construction
Jesse Beitel, Hughes Associates, Inc.
NFPA 285 Assembly Listings
• NFPA 285
– Required for multi-story Type I, II, III and IV buildings
that contain foam plastic insulation
– Many assemblies are approved
– Contact PIMA members
• ACC FSC Link to Fire Performance Material
• fsc.americanchemistry.com/Building-Code/FireMaterial
Topic #4 – Building Code Compliance –
Structural
• Structural
– Wall Bracing
– Wind Pressure
– Cladding Attachment
Structural Code Requirements are No
Different for Walls with CI
• Integration with Wall Bracing (IRC Section R602.10, IBC
section2308.3)
– Must have bracing with or without CI (no difference)
• Integration with framing requirements – stud sizing,
connections, wind uplift load path, etc.
– Must meet all framing requirements with or without CI
(no difference)
• Wind pressure resistance of exterior wall covering
assemblies (IRC R703.1.2, IBC 1403.3)
– All must provide wind pressure resistance
Wall Bracing
• Design factors impact wall bracing decisions
• fsc.americanchemistry.com/Applications
• Code-compliant bracing methods:
– Over-sheathing
– Foam between and/or over intermittent braced wall panels
• All methods have limitations, advantages and
disadvantages
Wind Pressure Resistance
• 2009/2012 IRC code provision proposed by PIMA
– Ensures
all sheathing
materials and
claddings meet
the code
Why? All Wall Coverings or Sheathings
are Subject to Wind Damage
• This is not just a CI problem…
Wood structural panels
Fiber board
Foam sheathing
Foam Sheathing Wind Pressure
Requirements
• Foam sheathing must resist wind pressure as part
of a wall covering assembly :
– Cladding/furring secures foam to resist negative design
wind pressure
• Typical fasteners intended for temporary wind
conditions
– Foam sheathing material must:
• Span between studs
• Have adequate bending strength
Code Compliance Resources
(wind pressure)
• TER No. 1006–01
– sbcri.info/fsc
– Provides path for code
compliance and building
official approval
• ANSI/SBCA/FS 100–2012
– sbcindustry.com/fs100.php
Vinyl Siding Over Foam Sheathing
(wind pressure)
• IRC 2009/2012:
DOE/IBHS/ACC-FSC/NAHBRC/VSI
Whole Building Wind Tunnel Test
Results – OSB/wrap/vinyl
Results – CI/vinyl (vinyl removed)
Cladding Attachment
• ACC-FSC, NYSERDA and SFA
research
– Adopted in NY energy code
• TER No. 1006-01
• Connection requirements
• Code compliance
• Proprietary
fasteners/connectors also
available
• Siding fastener embedment
must be maintained
Topic #4 – Building Code Compliance –
Building Science
• Building Science
– Water-Resistive Barriers (WRB)
– Air Barriers (AB)
– Vapor Retarders (VR)
– Moisture Control
Water-Resistive Barrier
•
•
•
•
WRBs required on all exterior walls
Code requires No. 15 asphalt felt or equal
Rain water is main concern
IRC section R703.2. IBC section 1404.2 is similar.
WRB (cont’d)
• WRB equivalence
– Confirmed by code compliance technical evaluation
report
• Foam sheathing products + flashing tapes = WRB
• Meets energy code and WRB requirements
– Designer/Builder must consider cost of WRB and
insulation strategy
Wait a minute!
• Does foam sheathing trap water in walls with
vapor retarder on the outside of a wall?
– Non-drainable EIFS contains foam sheathing
– Not so fast!
Past EIFS Problems are Misapplied to CI
• Past problems with EIFS
– No drainage of cladding
– No WRB layer
THESE PAST PROBLEMS WITH EIFS
HAVE ALL BEEN ADDRESSED IN
MODERN BUILDING CODES
Past EIFS Problems are Misapplied to CI
• Past problems with EIFS
– Face sealing not done or
done incorrectly
– Leaky window units
– Roof/wall flashing not
installed or improperly
installed
– Used with interior vapor
barrier in mixed warm-humid
climates
THESE PAST PROBLEMS WITH EIFS
HAVE ALL BEEN ADDRESSED IN
MODERN BUILDING CODES
WRB Addresses the “H20 Fear”
• WRBs
– Required for nearly all sidings and wall assemblies
– Must be applied in addition to foam sheathing when
not used as the approved WRB layer
• Fear of water intrusion is a good thing
• Follow current code requirements and technical
evaluation reports
Proper Use of VR with Foam Suppresses
Condensation and Promotes Drying
• IRC and IBC have vapor retarder options for CI
– Zones 1 and 2: Low perm on exterior side of wall
– IRC Section R601.3.1 and IBC section 1405.3.1.
“Warm Wall” VR Requirements
Foam Sheathing Creates
Warm, Breathable Wall
• Continuous insulation
Cladding
– Prevents condensation
Framing
• Non-insulated sheathings
– Greater condensation potential
Cold
Roof
Floor
Warm
Foam Sheathing has Flexible
Vapor Resistance Properties
• Foam sheathing has a successful track:
– WRB moisture performance
– VR properties:
• Full vapor barrier to
• Semi-permeable to
• Permeable
• Meets any climate/application requirement
Air Barrier Requirements
• Air permeability ≤ 0.004 cfm/ft2
• Comply with ASHRAE 90.1:
– Portland cement stucco
– Plywood, OSB sheathing
– XPS and foil-faced polyiso foam sheathing
– Gypsum board
– Spray foam
Topic #5: Installation Details
• Must be installed per manufacturer’s instructions
• Architects can provide construction details for plan
approval
Topic #5: Installation Details
• TER No. 1205–05 at
sbcri.info/fsc
• Provides path for code
compliance and approval
• DXF files also available
Topic #5: Installation Details
• Manufacturer installation instructions
• Detailing of CI wall assemblies with 6"+ of foam
• DOE’s Building America Program
• Alaska REMOTE house
Detailing Tips
• If no more than 2” of CI on a 2x4 wall
– Total wall thickness for window and door frames is no
different than 2x6 construction
– 3.5” + 2” = 5.5”
Detailing Tips
• For thicker applications of CI:
– May need to “box out” window and door openings
– Corner/trim details required
– Furring can provide siding attachment and positive
securement
Example Details (Thick Foam)
THANK YOU!
• Questions?
This concludes The American Institute of Architects
Continuing Education Systems Course
pima.org