Minnesota Lathing & Plastering Bureau
Suggested Guide Specifications For
PORTLAND CEMENT PLASTER (STUCCO) OVER CONVENTIONALLY FRAMED
AND SHEATHED SUBSTRATES
Section 09220
DISCLAIMER:
THIS GUIDE SPECIFICATION IS INTENDED FOR USE BY A QUALIFIED
SPECIFIER. THE GUIDE SPECIFICATION IS NOT INTENDED TO BE USED
VERBATIM AS AN ACTUAL SPECIFICATION WITHOUT APPROPRIATE
MODIFICATIONS FOR THE SPECIFIC USE INTENDED.
IT IS SUGGESTED THAT THIS GUIDE SPECIFICATION BE INTEGRATED INTO
AND COORDINATED WITH THE PROCEDURES OF EACH DESIGN FIRM AND
THE REQUIREMENTS OF SPECIFIC PROJECTS.
PART 1
1.01
GENERAL
SUMMARY
A. Section Description: Portland Cement Plaster over conventionally framed
and sheathed substrates.
B. Section Includes:
1. Water-Resistive Barrier
2. Lath and accessories
3. Plaster materials
4. Optional acrylic primer
5. Acrylic finish
C. Products installed by others but not supplied under this section:
1. Flashing Papers/Membranes: Rough window sills shall be properly
covered with reinforced coated vapor barrier, grade A or B product
under the direct supervision of the general contractor.
2. Flashing and Sheet Metal: Refer to Section 07600. Fabrication and
installation of related flashing and sheet metal components shall be
under direct supervision of general contractor. Mechanic shall be
experienced and competent in sheet metal trade.
3. Joint Sealers: Refer to Section 07900. Installation of joint sealant
shall be under direct supervision of the general contractor. Joint
sealant installer shall be experienced and competent in the
installation of elastomeric construction sealants.
1.02
RELATED SECTIONS
*NOTE TO SPECIFIER: DELETE OR ADD SECTIONS AS APPLICABLE TO SUIT PROJECT
REQUIREMENTS.
09220-1
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.
M.
N.
Section 01330 – Submittal Procedures
Section 05400 – Cold-Formed Metal Framing
Section 06110 – Wood Framing
Section 06160 – Sheathing
Section 07600 – Flashing and Sheet Metal
Section 07900 – Joint Sealers
Section 08100 – Metal Doors and Frames
Section 08500 – Windows
Section 08310 – Access Doors and Panels
Section 08400 – Entrances and Storefronts
Section 08520 – Aluminum Windows
Section 08550 – Wood Windows
Section 09250 – Gypsum Board
Section 10200 – Louvers and Vents
1.03
REFERENCES
A. American Society for Testing and Materials (ASTM) Standards. Most
current version.
1. ASTM C 79: Standard Specification for Treated Core and Nontreated
Core Gypsum Sheathing
2. ASTM C 91: Standard Specification for Masonry Cement
3. ASTM C 150: Standard Specification for Portland Cement
4. ASTM C 206: Standard Specification for Finishing Hydrated Lime
5. ASTM C 260: Standard Specification for Air-Entraining Admixtures for
Concrete
6. ASTM C 847: Standard Specification for Metal Lath
7. ASTM C 897: Standard Specification for Aggregate for Job-Mixed
Portland Cement- Based Plasters
8. ASTM C 926: Standard Specification for Application of Portland
Cement-Based Plaster
9. ASTM C 979: Standard Specification for Pigments for Integrally
Colored Concrete.
10. ASTM C 1063: Standard Specification for
11. Installation of Lathing and Furring to Receive Interior and Exterior
Portland Cement-Based Plaster
12. ASTM D 578: Standard Specification for Glass Fiber Strands
B. Portland Cement Plaster (Stucco) Manual: Portland Cement Association
C. UBC Standard 14-1: Kraft Waterproof Building Paper
1.04
SYSTEM DESCRIPTION
*NOTE TO SPECIFIER: EDIT ARTICLE B SUBSECTION 1 OR 2 BELOW TO SUIT PROJECT
REQUIREMENTS.
09220-2
A. Portland Cement Plaster (Stucco): A proportioned field mixed blend of
portland cement, masonry cement, sand, glass fibers, acrylic admixture
and potable water.
B. Finish Options.
1. Stucco Finish Coat: A proportioned field mixed blend of white
portland cement, hydrated lime, silica sand, acrylic admixture and
water.
2. Acrylic Finish: A proprietary mixture of 100 percent acrylic polymer,
aggregate, water and pigments.
C. Functional Criteria.
1. General: System shall be applied to vertically oriented substrates and
shall be protected from weather exposure harmful to coating
performance. Horizontally oriented surfaces shall be sloped for
positive drainage.
2. Substrate Conditions.
a. Substrates shall be sound, dry and free of dust, laitance and
contaminants.
b. Substrate dimensional tolerances: Flat within 1/4 (0.25) inch in
any 4 foot surface radius.
3. Expansion and Control Joints: Continuous expansion and control
joints shall be installed at locations noted on the drawings.
1.05
SUBMITTALS
*NOTE TO SPECIFIER: EDIT PARAGRAPHS BELOW TO SUIT PROJECT REQUIREMENTS.
A. Submit in accordance with Section 01330:
1. Product Data: Acrylic finish manufacturer's product information,
evaluation reports, testing information, certificates and warranty.
2. Shop Drawings: Detail drawings of [ ____________ ].
3. Samples: [Indicate quantity] 24 inch square samples of portland
cement plaster with [stucco] [acrylic finish] in each color and texture
specified, for preliminary approval. Each sample shall be prepared
using the same tools and techniques proposed for Project application.
1.06
QUALITY ASSURANCE
*NOTE TO SPECIFIER: EDIT PARAGRAPHS BELOW TO SUIT PROJECT REQUIREMENTS.
09220-3
A.
Plastering Contractor Qualifications
1. Contractor shall provide a list of completed work of equal scope.
2. Contractor shall hold a current certificate from the manufacturer of the
acrylic finish to apply that material.
B. Field Mock-Ups: Prepare field mock-ups to match preliminary samples
approved by the Architect.
1. The Architect shall determine location and size.
2. Mock-up(s) shall accurately represent the products to be installed on
the project, utilizing the same tools, and techniques proposed for
Project application.
3. The approved mock-up(s) shall be available and maintained at the
job site for reference.
C. Pre-Installation Conference: Schedule a pre-installation conference with
the Owner and/or Architect and General Contractor, to review the work of
this Section.
1.07
DELIVERY, STORAGE AND HANDLING
A. Deliver materials in original containers with labels intact and legible. Store
and protect materials in cool, dry location, out of sunlight, protected from
weather and other harmful environment, and at a temperature above 40°
F and below 110° F in accordance with manufacturer's instructions.
1.08
PROJECT/SITE CONDITIONS
*NOTE TO SPECIFIER: EDIT PARAGRAPHS BELOW TO SUIT THE PROJECT REQUIREMENTS.
A. Protect adjacent construction materials that are likely to be soiled by the
application process.
B. Environmental Requirements
1. Cement Plaster
a. Cold Weather
1) Do not use frozen materials or materials that have been
previously frozen.
2) Do not apply cement plaster to frozen surfaces or surfaces
containing frost.
3) Installation Ambient Air Temperature: Do not mix materials or
apply cement plaster when ambient temperature is less than
40° F. Ambient air temperature must remain at 40° F and
rising, and remain so for a minimum 24 hours thereafter.
b. Hot Weather
1) Protect cement plaster from uneven and excessive
evaporation during hot, windy, or dry weather. Avoid
application in direct sunlight.
2) In hot, windy or dry weather, the cement plaster should be
spray misted with potable water and then covered with a
single sheet of clear polyethylene plastic.
2. Acrylic Primer and Finish Coatings
09220-4
a. Comply with acrylic finish manufacturer's recommendations for
conditions affecting product performance
b. Protect installation from direct precipitation during the application
and the setting/curing period of primer and finish coat. Ensure
that the finish is fully set prior to removing protective covering.
c. Do not use frozen materials.
d. Apply acrylic primer and/or finish only when ambient air
temperature is 40° F and rising. Ambient air temperature shall
remain at 40° F for a minimum of 24 hours or longer if required,
until the coatings are completely dry.
e. Do not apply acrylic primer and/or finish to "brown" coat of
cement plaster if sun is directly on the wall surface and
temperature is 75° F or higher. Protect from direct sunlight.
PART 2
PRODUCTS
*NOTE TO SPECIFIER: EDIT PARAGRAPH A or B, DEPENDING ON SUBSTRATES. WOOD
BASED SHEATHINGS REQUIRE TWO LAYERS OF GRADE D BUILDING PAPER. EDIT
PARAGRAPH E BELOW TO LIST ACCEPTABLE ACRYLIC FINISHES
2.01
MATERIALS
A. Building Paper: Minnesota State Building Code, Type I, Grade D, Style 2.
1. Moisture Vapor Transmission: 35 grams/square meter/24 hours.
2. Water Resistance: 10 minutes minimum.
B. Asphalt Felt: International Building Code, International Residential Code,
No. 15 asphalt felt complying with ASTM D 226 for Type 1 felt.
C. Metal Lath: ASTM C847, self-furring, expanded galvanized steel lath, not
less than 3.4 pounds per square yard.
1. Shapes used as grounds shall be sized and dimensioned to provide
required plaster thicknesses.
2. Weather-exposed accessories shall be fabricated of galvanized steel
or zinc alloy materials.
3. Profile of casing beads and control joints shall provide screed flange
and/or embedment section.
4. Corner reinforcing shall be galvanized welded wire "Corneraid"
(Stockton Wire Products) or equal and be fabricated for full
embedment in the "brown" coat.
5. Provide standard trim items including control joints, casing beads and
base screeds.
D. Plaster Materials
1. Portland Cement: ASTM C150, Type I. Fresh and free of lumps.
2. Masonry Cement: ASTM C91. Fresh and free of lumps.
3. Hydrated Lime: ASTM C206, Type S.
4. Sand: ASTM C897. Moist and loose.
5. Water: Clean and potable.
09220-5
6. Fiber: ASTM D578. 0.5 inch long chopped fiberglass, polypropylene
or nylon strands, alkali-resistant.
7. Admixtures: Acrylic liquid admix Acryl 60 (Thoro systems Products,
Inc.) or equal.
E. Acrylic Finish
1. Factory prepared acrylic finish by [ indicate manufacturer(s) ].
2. [Indicate Color].
3. [Indicate Texture].
2.02
MIXES
*NOTE TO SPECIFIER: DELETE ARTICLE B, SUBSECTION 4 IF STUCCO FINISH WILL BE USED.
DELETE ARTICLE C, SUBSECTION 3 “STUCCO FINISH COAT” IF ACRYLIC FINISH WILL BE
USED.
A. General
1. Accurately proportion materials for each batch using measuring
devices of known volume.
2. Size batches for complete use within one hour after mixing.
3. Withhold 10 percent mixing water until mixing is nearly complete,
then add as needed to produce necessary consistency. Keep water
to a minimum.
B. Mechanical Mixing
1. Mix each batch separately.
2. Maintain mixer in clean condition before, during and after plaster
preparation.
3. Maintain mixer in continuous operation while charging mixer.
4. Mix factory prepared acrylic finish in accordance with manufacturers
instructions.
C. Mix Proportions by Volume
1. Dry Materials – Scratch Coat
a. 1 cubic foot portland cement
b. 1 cubic foot masonry cement.
c. 1.5 to 2.5 pounds of 1/2 inch chopped fiber.
d. 4 cubic feet sand.
2. Dry Materials – Brown Coat
a. 1 cubic foot portland cement.
b. 1 cubic foot masonry cement.
c. 1.5 to 2.5 pounds of 1/2 inch chopped fiber.
d. 5 to 6 cubic feet sand.
3. Dry Materials – Stucco Finish Coat
a. 1 cubic foot white portland cement
b. 3/4 cubic foot lime.
c. Pigments as required.
d. 3 cubic feet silica sand.
4. Mixing Liquid: 3 parts water and 1 part acrylic admixture.
09220-6
PART 3
EXECUTION
3.01
EXAMINATION
A. Examine the areas and conditions under which the work is to be
performed and notify the General Contractor in writing of conditions
detrimental to the proper and timely completion of the work.
B. Do not proceed with installation until unsatisfactory conditions have been
corrected.
3.02
INSTALLATION
A. Building Paper Asphalt Felt
1. Shall be free from holes and breaks other than those created by
fasteners.
2. Apply horizontally with the upper layer lapped over the lower layer not
less than 2 inches. Where vertical joints occur, paper shall be lapped
not less than 6 inches.
*NOTE: MINNESOTA STATE BUILDING CODE REQUIRES TWO LAYERS OF BUILDING PAPER
ON WOOD BASED SHEATHINGS.
B. Lath: Attach to framing or substrate in accordance with ASTM C1063,
lapping sides not less than 1/2 inch and ends not less than 1 inch.
C. Accessories
1. Attach level, plumb and true to create a proper screed and
depth for the cement plaster.
2. Install control joints to create panels relatively square, not larger than
144 square feet, and with no dimension exceeding 18 feet or a length
to width ratio of 2-1/2:1, unless otherwise shown on the Drawings.
D. Access Panels and Vents: Install accurately located and secured to
substrate with appropriate fasteners as per sections 08310 and 10200.
E. Portland Cement Plaster
1. Total thickness to meet code requirements.
2. Nominal plaster base coat thicknesses
a. First coat "scratch: 3/8 inch.
b. Second "brown": 3/8 inch.
3. Apply the scratch coat of cement plaster with sufficient force (by hand
or machine) to fill solidly openings in the lath.
4. Horizontally cross rake the scratch coat slightly to provide key for
second base coat. Coat must be uniform in thickness.
5. The double-back method of application (first and second coats are
applied and cured as one system) may be used.
a. Apply the second coat (brown) as soon as the scratch coat is
rigid.
6. Apply second coat to provide the required total thickness. Coat must
be uniform in thickness. Rod off level to screeds, to provide a true flat
plane. Follow this by wood floating or darbying the surface. Fill voids
and dress surface for finish.
09220-7
7. Completed second coat of cement plaster shall cure a minimum 7
days, prior to application of the finish coat.
*NOTE TO SPECIFIER: DELETE ONE OF THE FOLLOWING PARAGRAPHS TO SUIT THE
PROJECT REQUIREMENTS.
F. Stucco Finish Coat
1. Stucco finish coat shall be applied with sufficient material and
pressure to bond to and cover the brown coat.
G. Acrylic Finish Coat
1. Comply with manufacturers' instructions for mixing and application of
acrylic primer and acrylic finish.
2. Apply finish continuously and in one operation to the entire wall/soffit
area maintaining a "wet" edge so that completed finish is free of
scaffold lines and other imperfections due to application methods.
3. Completed finish texture(s) and color(s) shall be consistent with the
approved field samples/mock-ups.
09220-8
3.03
CLEANING
A. Remove spattering of plaster and acrylic finish from other finished
surfaces, paving and walks.
B. Remove and legally dispose of plaster system installation debris material
from project site.
04/2001
UPDATED 12/04
09220-9