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1.01 Scope
This specification covers the minimum requirements for
the application of a stucco
system, including general information pertaining to
the design and application of stucco.
NOTE:
This specification serves as a guide for the
development of a specification
for a particular project.
1.02 Contractor
Scope of Work
The work of this section includes all the equipment,
materials and labor necessary to
complete a stucco system, as indicated in this Stucco
Resource Guide and/or in project
documents (drawings and specifications).
1.03 Related
Sections (Section numbers
may be different depending upon specification format)
A. Section 01200
Project Meetings
B. Section 01630
Substitutions
NOTE:
Product substitutions will be considered only
under the terms and
conditions of section 01630.
C. Section 03300
Concrete
D. Section 04220
Unit Masonry
E. Section 05410
Load-Bearing Steel Studs
F. Section 06110
Wood Framing
G. Section 07240
Exterior Insulation and Finish Systems
H. Section 07600
Flashing and Sheet Metal
I. Section 07900
Joint Sealants
J. Section 09110
Non-Load-Bearing Steel Studs
K. Section 09250
Gypsum Sheathing Board
L. Section 09900
Painting
Details in this Stucco Resource Guide may show a single
layer of water-resistant
barrier for drawing clarity only. Refer to the Guide
Specification
section 3.38-B. The recommendation is for two layers.
1.04 Reference
Standards
A. National Building
Code Canada
B. City Building Code
Vancouver, B.C.
C. Building Codes - International,
NFRA, California, Uniform
D. Stucco Resource Guide
(NWCB)
E. American Concrete Institute
ACI 524R: Guide to Portland Cement Plastering
F. Federal Specifications
FS UU-B-790a: Building Papers, FS FF-N-105B: Nails,
Wire Staples for Application of Gypsum Board, FS QQ-W-461H:
Wire, Steel and Carbon (round
, bare & coated)
G. Portland Cement Plaster
(Stucco) Manual by PCA
H. ASTM Standards
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ASTM A526:
Steel Sheet, Hot-Dip Galvanized, Commercial Quality
ASTM C91: Masonry
Cement
ASTM C144: Aggregate
ASTM C150: Portland
Cement
ASTM C1328: Plastic
Cement
ASTM C206: Hydrated
Lime
ASTM C260: Air-Entraining
Admixtures
ASTM C494: Chemical
Admixtures for Concrete
ASTM C841: Installation
of Interior Lathing and Furring
ASTM C847: Metal Lath
ASTM C897: Aggregate
for Job-Mixed Portland Cement Plaster
ASTM C926: Application
of Portland Cement-Based Plaster
ASTM C932: Surface-Applied
Bonding Agents for Exterior Plastering
ASTM C979: Pigments
for Integrally Colored Concrete
ASTM C1032: Woven
Wire Plaster Base
ASTM C1063: Installation
of Lathing and Furring for Portland Cement Plaster
ASTM D1784: Rigid
Poly (Vinyl Chloride) PVC Compounds |
I. NAAMA Standard ML/SFA 920
NOTE:
Current editions at date of bid.
Use references and standards applicable to project.
1.05 Standards for Work
All work to be performed per Northwest Wall and Ceiling
Bureau recommendations.
A. Stucco Resource Guide and project construction documents.
NOTE:
Project construction documents to indicate type
of stucco assembly.
(Refer to Stucco Assemblies
section of this Stucco Resource Guide).
1.06 Submittals
A. Submittal requirements
by the stucco contractor are to be indicated in the
construc-tion documents. The following is a list of
documents that may be requested.
1. Product literature.
2. Samples and/or mock-ups
of system.
3. Certification of compliance
of materials and/or product literature.
4. Product literature
for all additives and proprietary components.
5. Finish sample for texture
and color for architect/owner approval.
NOTE:
Delete submittals not required.
Plastering contractor is not to proceed with
work until the required
submittals have been approved.
1.07 Quality
Assurance for Scope of Stucco Work
A. Pre-installation meeting.
B. Wall assembly fire-resistance
rating: _______ hour(s).
NOTE:
Construction documents shall indicate the type
of fire and/or sound
assembly rating required for project.
Construction documents to indicate fire-resistance
assembly test
required.
C. Scope of Work
Responsibilities Tables section of this Stucco
Resource Guide.
D. Stucco Quality
Assurance Checklist section of this Stucco Resource
Guide.
E. If required and feasible,
an approved finish coat on a portion of the building.
Location of finish coat sample as directed by the architect.
NOTE:
Delete if not applicable.
F. Applicator qualifications.
The plastering company shall meet the following
requirements:
1. Specialize in this
scope of work.
2. Have qualified and
properly trained people to perform work.
3. Be licensed, bonded
and insured.
4. Be in good financial
standing and capable of meeting the financial obligations
associated with the stucco scope of work on the project.
5. Have documented experience
in quality work of comparable scope.
6. Be recommended as a
qualified installer by NWCB or national or regional
Wall
and Ceiling Association (Plastering Association) or
approved by architect prior
to bid.
7. Contractor shall be
able to meet schedule requirements set at time of bid.
1.08 Delivery,
Storage, Handling and Setup
A. Materials at job site
to be in original containers with labels intact and
legible.
NOTE:
Exception: Basecoat sand
B. All trim accessories
and lath and/or other specified products to be shipped
to job site
in original containers. Any damaged or bent materials
shall be replaced.
C. All sack materials
to be stored above ground, dry and protected.
NOTE:
General contractor shall provide suitable site
for delivery, storage and
handling of materials.
General contractor shall provide suitable site
for plastering operation.
1.09 Environmental Conditions
A. Cold Weather Conditions:
1. Do not apply cement
plaster when ambient temperature is less than 35....F
(2....C).
2. Do not apply cement
plaster to any frozen surfaces or surfaces containing
frost.
Protect plaster coats against freezing for a period
of 24 hours after application.
3. Do not use frozen materials.
4. Hoarding (tenting),
heat and ventilation must be provided if cement plastering
is done in a temperature below 35....F (2....C).
NOTE:
The plastering contractor is not responsible
for these requirements.
Maintain adequate ventilation. Vent heaters to
outside.
5. Admixtures of cement
plaster for cold weather condition must be approved
and
used in accordance of manufacturers recommendations.
B. Warm Weather Conditions:
1. Protect the basecoats
and finish coat of cement plaster from uneven and
excessive evaporation in warm, windy weather. (Refer
to section on curing in
Part III)
NOTE:
Moist-curing is recommended.
2.01 Weather-Barrier
Backing/Water-Resistant Barrier
A. Water-resistant paperFederal
Specification UU-B-790a, grade D/30-minute or 60-
minute
B. Spunbonded olefin housewrap
manufactured and designed specifically for stucco.
C. Flashing material around
rough wall openings shall be a reinforced coated vapor-barrier,
grade A or B product, sheet metal, PVC plastic, or other
approved
membrane. The application of the flashing is not the
responsibility of the stucco contractor. Refer to the
Scope of Work Responsibilities section of
this Stucco
Resource Guide.
2.02 Window head, door, louver
and/or other penetration-plus wall opening pan-type
flashing - 26-gauge galvanized sheet metal, or PVC plastic.
NOTE:
Construction documents to indicate responsibility
for installation of
window head flashing and other stucco component flashing.
2.03 Tie Wire
Hanger and tie wire to be galvanized and annealed low-carbon
steel:
FSQQ-W-461g. AS
A. Hanger wire No. 8.1620
inch (4.12 mm)
B. Tie wire 18 gauge.0475
inch (1.22 mm)
C. Tie wire 16 gauge.0625
inch (1.59 mm)
2.04 Runner- and Cross-Furring
Channels
Cold-rolled galvanized steel channels, 1 1/2 inches
(38 mm) and 3/4 inches
(19 mm), a
minimum of 33,000 psi yield strength and a minimum of
.0538-inch bare steel thickness,
ASTM A526.
NOTE:
Suspended soffits/ceilings1 1/2-inch (38
mm) main runner, 3/4-inch
(19
mm) cross furring.
2.05 Furring Hat
Channels
Furring channel, galvanized 7/8-inch (22
mm), 20-gauge.
2.06 Fasteners Shall Comply
with:
A. NailsFS FF-N-105
B. StaplesFS FF-N-105
C. ScrewsASTM C
646
D. Power-driven fastenersper
building code approval
NOTE:
All fasteners to be corrosion-resistant and new.
2.07 Lath
NOTE:
Architect/specifier to indicate in construction
documents the type or
types of lath (A, B, C or D).
Delete types of lath not applicable.
Self-furring paperback lath (a
combination of lath and grade D 60-
minute water-resistant barrier) is not recommended
over a vertical
concrete or concrete masonry surface if the construction
documents.
require a water-resistant barrier for these surfaces.
A. Self-furring woven wire lath 17 gauge1 1/2-inch
(38 mm) opening, galvanized.
Shall comply with ASTM 1032.
NOTE:
For vertical surfaces only.
B. Self-furring diamond-mesh metal lath galvanized,
2.5 or 3.4 pounds per square yard.
Shall comply with ASTM 847.
NOTE:
2.5-pound-per-square-yard self-furring lath may
be used for a sheathed
framing construction system, 16 inches (400
mm) o.c., or for attachment
directly to concrete or concrete masonry.
C. Self-furring welded
wire lath, 16 gauge wire, galvanized openings not to
exceed 2
inches x 2 inches (50 mm x 50
mm). Shall comply with ASTM 933.
NOTE:
For vertical surfaces only.
D. 3/8-inch (10
mm) rib lath, galvanized. ASTM 847
NOTE:
For soffit condition with open-frame construction,
with supports 24
inches (600 mm) o.c.
2.08 Trim Accessories
NOTE:
Trim Accessories shall be fabricated from galvanized
steel, zinc (alloy),
PVC or anodized aluminum.
Depth (the grounds)
of accessories depends on the required thickness of
cement plaster basecoat, without the finish coat.
If the construction documents do not indicate
the type of accessories to
be installed, the plastering contractor shall select
the accessories in
accordance with these standards.
Accessories of PVC plastic or zinc (alloy)
are recommended if corrosion
is a concern because of environmental conditions.
Accessories with a finish surface lip flange
and/or embedment flange to
key into cement plaster are recommended.
It is recommended that PVC or aluminum reveals,
when used in
conjunction with 2-inch x 2-inch welded wire lath, incorporate
a strip of
expanded metal lath over the solid reveal flanges.
A. Steel accessories
per ASTM C 841
B. PVC plastic accessories
per ASTM D 1784 & C 1063
C. Aluminum accessories
from extruded alloy 6063 T5
D. General types of accessories:
1. Foundation weep screed:
______________________________________
2. Casing bead type no.
66 (JMOLD): _______________________________
3. Corner reinforcement
(corner bead): ______________________________
NOTE:
No. 1A expanded corner beads for interior gypsum
plaster are not
recommended.
E. Soffit vents ______________________________
F. Drip screeds ______________________________
G. Trim accessory joints
(control joints), expansion joints, or revels____________
NOTE:
Construction documents shall reference type,
style and manufacturers of
accessories.
Delete accessories not applicable for the project.
2.09 Bonding Agents
Bonding agents must conform to ASTM C 932, nonoxidizing,
non-crystallizing,
non-re-emulsifiable.
NOTE:
Apply per manufacturers recommendations.
Apply bonding agents only to clean, structurally
sound surfaces
(concrete, concrete masonry and
cement plaster).
Indicate manufacturer and brand name.
Delete if not applicable.
2.10 Plaster Materials
NOTE:
Delete cements not applicable.
A. Stucco basecoat
1. Portland Cement: ASTM
C 150 Type I or Type I/II
2. Masonry Cement: ASTM
C 91 Type I or Type I/II
3. 1-P Portland Cement:
ASTM C 595
4. Manufactured basecoat
cement for stucco
NOTE:
Indicate manufacturer as per NWCB and/or regional
wall and ceiling
association recommendation.
B. Hydrated lime: ASTM
C 206 Type S
C. Stucco finish
1. White portland cement,
ASTM 150 Type I or Type I/II
2. Regular portland cement,
ASTM 150 Type I or Type I/II
3. Manufactured stucco
finish
NOTE:
Indicate manufacturer as per NWCB and/or regional
wall and ceiling
association recommendation.
NOTE:
Do not use frozen aggregate.
A. Basecoat sand
NOTE:
ASTM C144 or C897
Natural or manufactured
Washed and free of deleterious materials
Locally available sand that approximates ASTM
C144 or C897, but
which may be nonconforming, can be approved for use
if past perfor-mance
indicates that it is an appropriate material.
B. Finish coat sand
NOTE:
ASTM C897
Natural or manufactured
Freshwater washed and free of deleterious materials
Locally available sand that approximates ASTM
C144 or C897, but
which may be nonconforming, can be approved for use
if past perfor-mance
indicates that it is an appropriate material.
2.12 Water Potable, clean, free
from impurities.
2.13 Admixtures
NOTE:
No household-type detergents or chlorides shall
be permitted.
Only admixtures manufactured specifically and
approved for use in a
stucco mix shall be permitted.
Admixtures without supporting documentation and
appropriate testing
or industry performance will not be approved by the
NWCB and/or
regional wall and ceiling association.
A. Fibers: 1/2-inch (13
mm) long, ASTM C 1116
NOTE:
Recommended as part of basic basecoat mix.
Only in basecoats, not in finish coat.
Polypropylene, nylon or alkali-resistant glass
fibers.
Use only types specifically manufactured for
a stucco basecoat and per
manufacturers recommendations.
B. Air-entraining admixtures:
NOTE:
ASTM C 260
Amount used shall be consistent with manufacturers
recommendations.
Use only products approved by the NWCB and/or
regional wall and
ceiling association.
C. Water-reducing admixtures
NOTE:
ASTM C494, Type A
Amount used shall be consistent with manufacturers
recommendations.
Use only products approved by the NWCB and/or
regional wall and
ceiling association.
D. Accelerating admixtures
NOTE:
ASTM C494, Type C and E.
Must be non-chloride or chloride with rust-inhibitors.
Amount used shall be consistent with manufacturers
recommendations.
Use only products approved by the NWCB and/or
regional wall and
ceiling association.
E. Pump-aid admixtures
NOTE:
Amount used to be consistent with manufacturers
recommendations.
Use only products approved by the NWCB and/or
regional wall and
ceiling association.
2.14 Coloring
Compounds for Job-site Stucco Finish
NOTE:
Delete if not required.
A prepackaged colors recommended
rather than B raw color
pigments.
A. Prepackaged colors
NOTE:
ASTM C979
Use only coloring compounds manufactured for
a job-site stucco finish.
Identify manufacturer, brand name and color code.
Mix with finish coat materials according to manufacturers
recommen-dations.
Best color uniformity can be achieved with prepackaged
products.
B. Raw Color Pigments
NOTE:
ASTM C979
Natural or synthetic iron oxides
Identify manufacturer, brand name and color code.
Mix with finish coat materials in proportions
which replicate a
previously approved sample.
Variation in the uniformity of color is normal
when raw pigments are used.
2.15 Mix Proportions
NOTE:
Proportions are parts by volume for basecoats
and job-site stucco finish
coat.
Use standard measuring devices and know volumes
for all materials.
Sequential batches to be proportionally alike.
All mixing in a mechanical mixer.
Continue to mix for 3-5 minutes after all ingredients
have been added.
Add fibers 2-3 minutes before mixing is complete.
Factory-prepared stucco finish coat per manufacturers
requirements.
Admixtures per manufacturers requirements.
Cement materials shall be based on full bag increments.
Shovel count can be used for measuring sand if
standardized first.
Use enough water to produce suitably plastic
cementitious material,
keeping water to a minimum.
Sequence of materials: (1)
water, (2) half of sand,
(3) all of the cement
and/or lime, (4) balance
of sand and (5) water for
workability.
Brown coat may contain the higher
volume of sand.
For integral color finish, factory-prepared finishes
will result in truer
and more consistent color.
Sand per sum of cementitious material.
For mix no. 1, 3, 4 and 5, volume of sand in
first coat shall the same or
less than volume in the second (brown)
coat, not to exceed 4 parts of
sand per sum of cementitious materials.
For mix no. 2, volume of sand in first coat shall
be the same or less than
volume in the second (brown)
coat, not to exceed 3 1/2 parts of sand per
sum of cementitious materials.
Amount of fibers per mix per manufacturers
recommendations.
A. Basecoat mix parts by volume
(ASTM C 926) and finish coat mix parts by volume
(ASTM C926)
NOTE:
Select one of the five mixes or another approved
ASTM C926 mix for the
project. Do not interchange components. Once project
has been started,
do not switch to another mix.
Architect to indicate which one of the five mixes
to use. If mix is not
shown in construction documents, plastering contractor
may use one of
the five mixes shown in this Guide Specification.
Delete mixes not to be used in the project.
Volume of sand per sum of cementitious material.
Mix No. 1Basecoat
Portland cement .............................. 1
Masonry cement ............................. 1
Sand ............................................ 3
1/2 - 4 1/2
Fibers ............................................
per manufacturers recommendations
Mix No. 2Basecoat
Portland cement .............................. 1
Lime ............................................ 1/4
- 1/2
Sand ............................................ 3-4
Fibers ............................................
per manufacturers recommendations
Mix No. 3Basecoat
1-P portland cement ........................ 1
Masonry cement ............................. 1
Sand ............................................ 3
1/2 - 4 1/2
Fibers ............................................
per manufacturers recommendations
Mix No. 4Basecoat
Plastic cement ................................. 1
Sand ............................................ 3
1/2 - 4 1/2
Fibers ............................................
per manufacturers recommendations
Mix No. 5Basecoat
Portland cement .............................. 1
Plastic cement ................................. 1
Sand ............................................ 3
1/2 - 4 1/2
Fibers ............................................
per manufacturers recommendations
B. Job-site stucco finish
coat
White portland cement.................... 1
(or regular portland cement)
Lime ............................................ 1
- 2
Sand ............................................ 3
NOTE:
Add manufactured coloring compounds to job-site
stucco finish mix per
manufacturers recommendations.
Delete if not applicable.
C. Manufactured stucco
finish
NOTE:
Mix and apply per manufacturers recommendation.
Manufacturer to be approved by NWCB and/or regional
wall and ceiling.
2.16 Acrylic Finish
NOTE:
A proprietary finish material by EIFS manufacturer,
approved by NWCB
and/or regional wall and ceiling association.
100-percent acrylic polymer material in finish.
Mix and apply per manufacturers recommendations.
Delete if not applicable.
3.01 Examination
A. Prior to starting lathing
or plastering work, carefully inspect installed work
of other
trades to verify that work is complete to the point
where work of this section may
properly commence.
B. Notify the architect
or proper authorities in writing of conditions detrimental
to the
proper and timely completion of the lathing and/or plastering
work.
C. Do not begin installation
until all unsatisfactory conditions are resolved.
D. A pre-construction
meeting is recommended with the architect and/or owner,
primary
contractor and representatives responsible for the windows,
framing, flashing, roofing,
sealants, stucco and any other building components interfacing
with the stucco.
NOTE:
The examination of conditions is the responsibility
of all parties involved
in the project.
3.02 Performance
A. The work shall
be performed by a skilled and trained work crew.
NOTE:
Work shall be performed to create a rigid, secure,
level or plumb finish
surface, with line dimensions and/or contours as indicated
in reference
standards or project documents.
B. Install specified
products and/or systems in accordance with reference
standards,
manufacturers recommendations and this Stucco
Resource Guide, unless indicated
otherwise in project documents.
C. Flashings shall be
installed prior to start of lathing or may be required
to be
integrated at the time of lathing. Flashing is not the
scope of work of the contractor
responsible for the stucco assembly.
3.03 Installation of Stucco
Trim Accessories
NOTE:
Refer to details and other portions of this Stucco
Resource Guide for
additional information
A. Verify that substrate
and work by other trades are complete to the point at
which
installation of trim accessories may properly commence.
NOTE:
Do not begin work until unsatisfactory conditions
are resolved.
B. Attachments shall be
firm enough to hold trim accessories in place without
misalignment during plastering.
NOTE:
Flanges or attachment points of trim accessories
shall be secured
to substrate in accordance with requirements of manufacturers
of
approved fasteners. Space per manufacturers directions.
It is recommended that PVC or aluminum reveals,
when used in
conjunction with 2-inch x 2-inch welded wire lath, incorporate
a strip of
expanded metal lath over the solid reveal flanges.
C. It is recommended
that trim accessories have a small top flange lip
that goes over
the stucco and/or flange that embeds into the stucco.
D. Zinc alloy or PVC is
recommended if trim accessories are exposed to a high-salt
environment.
E. Install individual
trim-accessory sections to each other at end joints
for accurate
alignment.
F. Install trim accessories
in a manner that ensures a true, level and plumb stucco
surface, and moisture resistant.
NOTE:
Accurate alignment of trim accessories may require
shimming, limited to
the thickness of stucco.
Sections of flashing or trim accessories that
butt each other (at corners
or another condition) need to be lapped, caulked,
or have a strip of self-adhering
membrane over the joints. This is to prevent moisture
from
getting to the building structure.
G. Install the trim accessories
in accordance with the required thickness of stucco
basecoat and finish coat requirements. (Refer
to Plaster Thickness section)
NOTE:
Depth (grounds)
of trim accessory to be in accordance with the
thickness of stucco. (Refer to
Plaster Thickness Tables)
For example, 3/4-inch (19-mm)
stucco requires a minimum ground of a
casing bead to be 3/4 inch (19
mm).
H. Install the longest
possible lengths of trim accessories. A minimum continuous
section (length) of 7 feet
(2 m) is recommended.
3.04 Trim Accessory Joints
NOTE:
Installation to be in accordance with section
3.03Installation of
Stucco Trim Accessories.
Trim accessory joints refer to various types:
control joints, expansion
joints, reveals, and/or any other devices or systems
that divide (break) the
stucco membrane surface.
Architect is to select the type of joint and
indicate on drawing the
location of joints.
Trim accessory joints provide relief of stresses
from the structure and
cement-plaster curing process.
Trim accessory joints provide for a plaster stop
and a screed.
Aluminum and/or PVC reveals require that when
the lath is installed
over the flange, it totally covers it. The welded wire
and woven wire lath
shall be installed so as the crotch of the lath is over
the flange.
It is recommended that PVC or aluminum reveals,
when used in
conjunction with 2-inch x 2-inch welded wire lath, incorporate
a strip of
expanded metal lath over the reveal flanges.
A. The water-resistant
barrier must continue unbroken behind trim accessory
joints in
vertical or horizontal direction.
B. Locate to trim accessory
joints strategically at points where building movement
is
anticipated.
1. Wall penetrations
2. Structural plate lines
3. Junctures of dissimilar
substrates
4. Existing construction
joints in structure
5. Columns
6. Cantilevered areas
C. Joints are recommended
in stucco assemblies with lath reinforcement but have
limited use in direct-applied stucco over concrete or
concrete masonry surface.
D. It is recommended that
trim accessory joints be weather-sealed by embedment
in
caulking at intersections when placed end-to-end and
at the terminations.
E. It is recommended to
install vertical joints continuously and to abut horizontal
joints
to vertical (be sure that water-resistant
barrier runs continuously behind joints).
NOTE:
The use of horizontal reveals, flashing designs
and/or other horizontal
surface breaks may prevent continuous vertical joints.
Expansion joints govern over control joints.
F. Install longest possible
lengths. No termination of a section within 24 inches
(600
mm) of an intersection, with the exception of
pre-manufactured trim accessory joint
intersections.
G. It is recommended
that trim accessory joints be installed on framed, sheathed
construction so as to create stucco panel of 150 to
180 square feet (14 m 2 to 17
m 2 )
in as square a configuration as possible.
NOTE:
Maximum recommended length of a panel is 18 feet
(5.5 m). Panel size
approximately 3-to-1 ratio.
H. It is recommended
that trim accessory joints be installed with concrete
or concrete
masonry construction so as to create a stucco assembly
(with lath reinforcement)
of
200 to 250 square feet (18 m 2
to 23 m 2 ).
I. Installing control
joints over continuous lath is an approved method.
NOTE:
Control joint is a one-piece trim accessory.
Control joint may be installed in the field
of panel only if there is
framing or wood sheathing continuous substrate behind
it for attachment.
Control joints to be wire tied to lath with 18-gauge
tie wire (recom-mended
method when lath goes over sheathing board other than
wood).
J. The recommendation
for the installation of expansion joints or reveals
is to break the
lath and lap it over on top of each of the flanges.
NOTE:
Control joints may also serve as expansion joints,
if so specified and
detailed.
Expansion joints and/or reveals may consist of
one or two pieces.
Control joints are limited in their degree of
movement. Two-piece
expansion joints provide greater movement.
K. Sheathed framed construction
with vertical trim accessory joints that require the
lath
to be terminated (cut)
and installed on top of the flanges shall be placed
at framing
member locations. Lath shall be attached with appropriate
fasteners through the
trim accessory flange, sheathing and into the framing
member.
NOTE:
The lath/flange on each side of the trim accessory
joint to be attached to
a framing member. Double framing supports would be required
at these
locations.
This condition does not pertain to control joints
installed over continu-ous
lath.
3.05 Lathing for Soffits
A. Suspended soffits/ceilings
shall be erected so that the finished basecoat cement
plaster surface is true to line and level, with allowable
tolerance of 1/4 inch (6 mm)
in 10 feet (3.1 m)
NOTE:
Construction documents shall indicate the approximate
amount of
deflection of structure to which suspended soffit is
attached..34 Northwest
No attachment of soffit/ceiling abutting to walls
or fascia (in order to
prevent transfer of stresses).
Vertical compression struts to withstand upward
wind pressures are not
required unless indicated in project documents.
NWCB recommends a soffit framing system with
sheathing (refer to
3.06-B) because it incorporates a gypsum sheathing
board attached to
furring hat channels. This type of assembly
produces a better stucco
soffit. The sheathing board provides rigidity to the
framing system and
helps produce a uniform stucco thickness.
Refer to sections 3.03 and 3.04.
B. Spacing, attachment,
size and type of hangers, fasteners and inserts shall
be as
required in reference standards in section 1.04.
NOTE:
Fasteners and inserts shall have up-to-date testing
information from
manufacturers.
3.06 Lathing Systems
for Suspended Soffits (for details,
see soffit section)
NOTE:
For additional suspended soffit configurations
(size, spans and spacing),
refer to reference standards in section 1.04.
(ASTM C1063)
Construction documents to indicate either the
soffit framing system
(refer to 3.06 A) or soffit
framing system with sheathing (refer
to 3.06 B).
A. Soffit framing system
1. Hanger wires maximum
support 16 square feet (1.5 m
2 )
2. 1 1/2-inch
(38-mm) main runner channels o.c. spacing 48
inches (1.2 m)
3. 3/4-inch (19-mm)
cross-furring channels o.c. spacing 13 to 16 inches
(325 to
400 mm)
4. 3.4-pound-per-square-yard
diamond-mesh lath
5. Wire-tie lath to cross-furring
channels with 18-gauge tie-wire, 6 inches (150
mm) o.c.
B. Soffit framing system
with sheathing
1. Hanger wires, maximum
support 16 square feet (1.5 m
2 )
2. 1 1/2-inch (38-mm)
main runner channels, maximum o.c. spacing 48 inches
(1.2 m)
3. 20-gauge furring hat
channels, spaced maximum 16 inches (400
mm)
4. 1/2-inch (13-mm)
gypsum sheathing board
5. 3.4-pound-per-square-yard
self-furring diamond-mesh lath attached through
gypsum sheathing board into furring channels, maximum
6 inches (150 mm)
o.c. with type S screwswafer head1 inch
(25 mm) long.35 Northwest
3.07 Soffit Lathing System to
Wood Joist
A. 3/8 inch (10 mm) rib
lath attached 6 inches (150 mm)
o.c., with one of the following:
1. Roofing nails: 11
gauge 7/16-inch diameter head 1-inch long
2. Staples: 16 gauge
3/4-inch crown 1 1/4-inch long
3. Screws: type W
wafer head 1-inch long
NOTE:
Fasteners must penetrate into the wood a minimum
of 3/4 inch (19 mm)
both legs of staple must penetrate wood. Fasteners to
be centered,
minimum 3/8 inch (10 mm) from edge of wood joist.
Maximum spacing of wood joist 24 inches (600
mm) o.c.
3.08 Application of Stucco Basecoat
for Soffits
NOTE:
Do not use the double-back method of applying
the basecoats.
Verify trim accessories and lath are installed
so as to provide proper
screeds, thickness and alignment for plastering.
Do not begin plastering work until unsatisfactory
conditions are resolved.
Cement plaster can be applied by trowel or machine.
Apply basecoat to entire horizontal surface and/or
section without
interruption or cold joints.
A. Indicate the permissible
mix number and its proportions to be used for the basecoat
NOTE:
Delete basecoat mixes not applicable to this
project.
Do not change selected mix or proportions after
plastering operation has
started.
Measurement of ingredients (materials
of the mix) to be done with
devices of known volume, accurate, and successive batches
proportion-ally
alike.
Use only enough mix water to make plaster a workable
consistency.
Admixtures to be submitted for approval.
Basecoat admixtures designed for improving the
mix or for enhancing the
plaster application must have been manufactured strictly
for that
purpose.
Admixtures must be accurately measured and used
only in accordance
with manufacturers recommendations.
B. Apply stucco first
(scratch) coat in a nominal thickness
of 3/8 inch (10 mm). First
coat to completely embed the lath. First coat to be
thick enough to allow for scoring
of cement plaster surface. (Refer
to Plaster Thickness Tables)
NOTE:
Scoring of the first coat should be uniform and
shallow, approximately 1/
8 inch (3 mm).
C. Moist cure the first (scratch)
coat for a minimum of 48 hours before application of
the second (brown)
coat.
NOTE:
First coat to be hard and rigid before receiving
the second coat.
D. Apply stucco second
(brown) coat
in a nominal thickness of 3/8 inch (10
mm)
over stucco first coat. Second coat thickness to bring
the combined basecoats (first
and second) thickness to a nominal thickness
of 3/4 inch (19 mm). (Refer to
Plaster
Thickness Tables)
NOTE:
Apply second coat over a damp first coat. If
required, apply a fine spray
of clean water, so as to dampen only. Do not saturate.
Allow water
sheen to disappear before applying the second coat.
E. Apply the second coat
with sufficient material and pressure to ensure a tight
uniform
bond to the first coat.
NOTE:
Apply second coat so as not to deform or crack
the first coat.
F. Rod the second coat
to a true, even plane, filling surface defects with
cement plaster.
G. Trowel-float the second
coat surface uniformly.
NOTE:
The floating process densifies the basecoat and
provides a proper surface
for the finish coat application.
Float the basecoat after it has set and when
moisture is still present in it.
Floating the basecoat that is to receive an acrylic
finish coat is critical
because of the thickness of this finish.
3.09 Curing of Soffit BasecoatRefer
to section 3.40.
NOTE:
After the second coat has been applied, moist
cure it as required, and then
wait a minimum of seven days before the start of finish
coat application.
3.10 Stucco Finish CoatRefer to section 3.41.
3.11 Acrylic Finish CoatRefer to section 3.42.
3.12 Additional Types of FinishesRefer to section
3.43.
3.13 Cement Plaster Direct to Concrete
NOTE:
Concrete to be cured for a minimum of 28 days..37
Northwest
Not recommended for horizontal surfaces (other
than ceilings/soffits).
Concrete surface to be straight and true, in
accordance with standards.
Concrete surface to be clean, no form release
agents, no curing compounds
or other elements in concrete surface preventing a proper
bond.
Concrete should be in good condition and have
uniform absorption rate
over entire surface.
Concrete in poor condition (spalling, delamination,
voids) or other
surface defects requires repair before plastering.
If the concrete surface is not in proper condition,
self-furring lath must
be installed.
If there is any concern about the bondability
of the cement plaster direct
to concrete, a test area is recommended. Apply 1/4
- 1/2 thick, by 1x1
of cement plaster basecoat to concrete; let it cure
for 3 - 4 days. Then try
to remove it. Do this type of test at more than one
location.
Acrylic finish coat is not recommended for concrete
retaining walls.
3.14 Stucco Finish Coat Direct to ConcreteRefer
to Stucco Wall Assemblies section
detail A6 in this Stucco Resource Guide.
NOTE:
The finish coat over concrete is used to enhance
the surface appearance;
it is not designed to true up the surface.
Smooth troweled stucco finishes are not recommended
because of the
possibility of very fine map cracking. If smooth troweled
finish is specified,
surface should be painted with a high-quality acrylic
exterior paint.
A. Apply liquid bonding
agent directly to concrete surface in accordance with
the
recommendation of manufacturer of the material.
B. Application of the
stucco finish coatRefer to section 3.41.
3.15 Acrylic Finish Coat
Direct to ConcreteRefer to section 3.42.
NOTE:
Do not apply finish until all irregularities
on the concrete surface have
been corrected.
3.16 Two Coat Stucco Direct
to ConcreteRefer
to Stucco Wall Assemblies section
detail A7 in this Stucco Resource Guide.
NOTE:
This method provides for an economical way of
creating an acceptable
level finished wall surface.
The system provides a leveling basecoat (brown
coat) over the concrete
surface and makes a suitable base for the finish coat
with limited total
stucco thickness of 1/2 inch (13
mm).
Refer to section 3.13..38 Northwest
A. Apply liquid bonding
agent directly to concrete surface only in accordance
with the
recommendation of manufacturer of the material.
B. Install trim accessoriestermination
trim accessory, corner reinforcements (corner
beads), trim accessory joints (control joints) and other
specified accessories in
accordance with sections 3.03 and 3.04.
NOTE:
Install per related detail sections of this Stucco
Resource Guide.
Delete trim accessories not applicable.
Depth (grounds)
of trim accessory to be in accordance with the thickness
of stucco. (Refer to Plaster Thickness
Tables)
Install so as to provide the required screed
and ground and to create a
true and level surface. (Refer
to Plaster Thickness Tables)
C. Trim accessory attachment
NOTE:
The installation of fasteners and their pullout
resistance shall be in
accordance with the manufacturers recommendations
and safety
requirements.
If there is any question on the pullout strength
of the fasteners, sample
testing on the wall is recommended.
The psi of the concrete, how long the concrete
has cured and the physical
condition of the concrete affect the selection of proper
fasteners for the
attachment of trim accessories and lath.
Fastener head shall be capable of lapping over
two or more strands
(recommended to be placed at the
crotch of the trim accessory flange)
and/or lapped over attachment hole.
D. Indicate type of stucco
termination trim accessory (casing
bead):
_________________________________________________________________
Indicate name of manufacturer (optional):
_______________________________
E. Attach termination
trim accessory to concrete surface with hardened concrete
stub
nails; low-velocity, power-actuated pins or drill-and-drive
fasteners. Fastener heads
minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch (19
mm);
spacing of fasteners 8 to 12 inches (200
to 300 mm) o.c.
F. Indicate the type of
corner reinforcement (corner bead):
_______________________
Indicate name of manufacturer (optional):
__________________________________
NOTE:
Corner reinforcement is recommended at vertical
exterior and slanted
corners.
G. Attach corner reinforcement
to concrete surface with hardened concrete stub nails;
low-velocity, power-actuated pins or drill-and-drive
fasteners. Fastener heads
minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch ( 19 mm);
spacing of fasteners 12 inches (300
mm) o.c. staggered.
H. Indicate the type of
trim accessory joint (control
joint, expansion joint, reveal or
other style): __________________________________________________________
Indicate name of manufacturer (optional):__________________________________
NOTE:
The use of trim accessory joints (control
joints) is limited on a stucco
system direct to concrete masonry, and they are not
required as
frequently as for framed construction.
Control or expansion joints are recommended at
locations of concrete
expansion joints (construction
joints).
Control joints are recommended if the area exceeds
250 square feet
(23 m 2 ). Panel should
be in as square a configuration as possible.
The location of trim accessory joints and the
type are by the architect.
I. Attach trim accessory
joints to concrete surface with hardened concrete stub
nails;
low-velocity, power-actuated pins or drill-and-drive
fasteners. Fastener heads
minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch (19 mm);
spacing of fasteners 12 inches (300
mm) o.c. staggered.
J. Application of stucco basecoat
NOTE:
Inspect concrete surface to ensure it is in proper
condition for a direct
application of cement plaster.
Do not begin plastering work until unsatisfactory
conditions are
resolved.
Cement plaster can be applied by trowel or machine.
Apply basecoat to entire wall panel and/or section
without interruption
or cold joints.
K. Indicate the permissible
mix and its proportions to be used for the basecoat
NOTE:
Delete basecoat mixes not applicable to this
project.
Do not change selected mix or proportions after
plastering operation has
started.
Measurement of ingredients (materials
of the mix) to be done with a
device of known volume. Measure accurately. Make successive
batches
proportionally alike.
Use only enough mix water to make plaster a workable
consistency.
Admixtures are for improving the basecoat mix
or enhancing the plaster
application. Use products manufactured strictly for
this purpose and in
accordance with manufacturers recommendations.
L. Apply basecoat (brown
coat) in a nominal thickness of 3/8 inch (10 mm). Refer
to
Plaster Thickness Tables.
NOTE:
Basecoat direct to concrete 3/8 inch to 1/2 inch
(10 to 13 mm) thick, not
greater than 1/2 inch (13 mm)
M. Apply basecoat with
sufficient material and pressure to ensure tight contact
with
concrete surface and uniform thickness.
N. Rod the basecoat to
a true and even plane, filling basecoat surface defects
with
cement plaster.
O. Trowel-float the basecoat
surface uniformly.
NOTE:
The floating process densifies the basecoat and
provides a proper surface
for the finish coat application.
Float the basecoat after it has set and when
moisture is still present in it.
(The float should not adhere to
the surface that is to be worked)
3.17 Curing of BasecoatRefer to section 3.40.
3.18 Stucco Finish CoatRefer to section 3.41.
3.19 Acrylic Finish CoatRefer to section 3.42.
3.20 Additional Types of FinishesRefer to section
3.43.
3.21 Two-Coat Stucco Direct to Concrete Masonry CMURefer
to Stucco Wall
Assemblies section detail A4 in this Stucco Resource
Guide.
NOTE:
This method consists of a leveling basecoat (brown
coat) followed by a
finish coat.
Concrete masonry is an excellent substrate for
direct-applied cement plaster.
The two-coat stucco system trues up the surface,
creating a water-resistant
membrane and pleasing finished surface.
This system is recommended and commonly used
over a concrete
masonry substrate or other similar types of surfaces
that will develop the
required bond.
Reinforcement lath is omitted in this system.
Do not tool the mortar
joints of the concrete masonry assembly. It is recommended
to have
mortar joints struck flush with the surface.
Concrete masonry wall must have been cured in
accordance with
industry standards (a minimum
of 30 days) before application of cement
plaster basecoat and carry the designed dead loads before
plastering.
Concrete masonry surface to be clean, no substances
on the surface or in
the units and/or joints which would prevent a proper
bond with the
stucco basecoat.
Coated (painted) concrete masonry surfaces require
self-furring lath
attached in accordance with standards or the removal
of the coating.
The degree of the masonry wall misalignment will
dictate either the
direct application of a two-coat stucco system or the
use of self-furring
lath in order to achieve a true wall surface plane.
Concrete masonry assembly shall be constructed
in accordance with its
application standards.
A. Install trim accessoriestermination
trim accessories (casing beads),
corner
reinforcements (corner beads);
trim accessory joints (control
joints) and other
specified accessories according to sections 3.03 and
3.04 to concrete masonry
substrate.
NOTE:
Install per related detail sections of this Stucco
Resource Guide.
Delete trim accessories not applicable to project.
Depth (grounds)
of trim accessory shall be in accordance with the
thickness of stucco. (Refer to
Plaster Thickness Tables)
Install so as to provide the required screed
and ground in accordance
with a nominal stucco thickness of 1/2 inch (13
mm) and to create a true
and level surface. (Refer to Plaster
Thickness Tables)
B. Trim accessory attachment
NOTE:
The installation of fasteners and their pullout-resistance
requirements
shall be in accordance with the manufacturers
requirements and safety
recommendations.
If there is any question on the pullout strength
of the fasteners, sample
testing on the wall is recommended.
Fastener head shall be capable of lapping over
two or more strands
(recommended to be placed at the
crotch of the trim accessory) and/or
lapped over attachment hole.
Spacing or fasteners depends on type and size
of the concrete masonry
units.
For substrates of concrete masonry units, brick
or tile, it is recommended
that the fasteners be placed in the mortar joints. This
will minimize
damage to the individual units.
C. Indicate types of
termination trim accessories (casing
beads):
____________________________________________________________________
Indicate name of manufacturer (optional):__________________________________
D. Attach termination
trim accessory to concrete masonry surface with hardened
concrete stub nails; low-velocity, power-actuated pins
or drill-and-drive fasteners.
Fastener heads minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch
(19 mm); spacing of fasteners
8 to 12 inches (200 to 300 mm)
o.c.
E. Indicate the type of
corner reinforcement (corner
bead):_______________________
Indicate name of manufacturer (optional):
_________________________________
NOTE:
Corner reinforcement is recommended at vertical
exterior and slanted
corners.
F. Attach corner reinforcement
to concrete masonry surface with hardened concrete
stub nails; low-velocity, power-actuated pins or drill-and-drive
fasteners. Fastener
heads minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch
( 19
mm); spacing of fasteners 12 inches (300
mm) o.c. staggered.
G. Indicate the type of
trim accessory joint (control
joint, expansion joint, reveal or
other style): _________________________________________________________
Indicate name of manufacturer (optional):
_________________________________
NOTE:
Control or expansion joints are recommended at
locations of concrete
masonry expansion joints (construction
joints).
The use of trim accessory joints (control
joints) is limited on a stucco
system direct to concrete masonry and are not recommended
as
frequently as for framed construction.
Control joints are recommended if the area exceeds
250 square feet
(23 m 2 ). Panel should
be in as square a configuration as possible.
The location of trim accessory joints and the
type are by the architect.
H. Attach trim accessory
joint to concrete masonry surface with hardened concrete
stub
nails; low-velocity, power-actuated pins or drill-and-drive
fasteners. Fastener heads
minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch (19
mm);
spacing of fasteners 12 inches (300
mm) o.c. staggered.
I. Application of stucco
basecoat
NOTE:
Inspect concrete masonry surface to ensure it
is in proper condition for a
direct application of cement plaster.
Do not begin plastering work until unsatisfactory
conditions are
resolved.
Cement plaster can be applied by trowel or machine.
Apply basecoat to entire wall panel and/or section
without interruption
or cold joints.
J. Indicate the permissible
mix number and its proportions to be used for the basecoat:
NOTE:
Delete basecoat mixes not applicable to this
project.
Do not change selected mix or proportions after
plastering operation has
started.
Measurement of ingredients (materials of the
mix) to be done with a
device of known volume. Measure accurately. Make successive
batches
proportionally alike.
Use only enough mix water to make plaster a workable
consistency.
Admixtures are for improving the basecoat mix
or enhancing the plaster
application. Use products manufactured strictly for
this purpose and in
accordance with manufacturers recommendations.
K. Apply basecoat (brown
coat) in a nominal thickness of 1/2 inch (13
mm). Refer to
Plaster Thickness Tables.
NOTE:
Basecoat direct to concrete masonry surface 3/8
inch (10 mm) to 5/8 inch
(13 mm) thick, not greater
than 5/8 inch (13 mm).
L. Apply basecoat with
sufficient material and pressure to ensure tight contact
with
concrete masonry surface and uniform thickness.
NOTE:
Dampen the substrate by spraying with clean water
just before starting
plastering.
It is advisable first to apply a dash bond coat
or liquid bonder to the
concrete masonry surface in order to uniform the suction
and help
prevent the telegraphing of the mortar joints. Dash
coat does not replace
one of the specified number of coats.
M. Rod the basecoat to
a true, even plane, filling basecoat surface defects
with cement
plaster.
N. Trowel-float the basecoat
surface uniformly.
NOTE:
The floating process densifies the basecoat and
provides a proper surface
for the finish coat application.
Float the basecoat after it has set and when
moisture is still present in it.
(The float should not adhere to
the surface that is to be worked)
3.22 Curing of BasecoatRefer to section 3.40.
3.23 Stucco Finish CoatRefer to section 3.41.
3.24 Acrylic Finish CoatRefer to section 3.42.
3.25 Additional Types of FinishesRefer to section
3.43.
3.26 Stucco Assembly Attached to ConcreteRefer
to Stucco Wall Assemblies section
detail A8 in this Stucco Resource Guide.
NOTE:
This system is recommended if a greater thickness
of stucco is necessary
or if the concrete surface will not provide an adequate
bond for direct
application of cement plaster.
Concrete surface to be in good condition, no
large voids, no spalling and
no delamination. Concrete to be true and straight.
Surface to be within tolerance standards for
a concrete tilt-up or poured-in-
place walls.
Concrete to be cured a minimum of 30 days before
start of any stucco
work.
Do not begin installing trim accessories or lath
until all unsatisfactory
conditions are resolved.
A water-resistant barrier is not required for
this stucco assembly. A
combination self-furring lath and water-resistant barrier
(paperback
lath) is recommended if the project documents
specify a water-resistant
barrier.
A. Install trim accessoriestermination
trim accessories (casing beads),
corner
reinforcements (corner beads),
trim accessory joints (control
joints) and other
specified accessories in accordance with sections 3.03
and 3.04.
NOTE:
Install per related detail sections of this Stucco
Resource Guide.
Delete trim accessories not applicable to project.
Depth (grounds)
of trim accessory shall be in accordance with the
thickness of stucco. Refer to Plaster Thickness Tables.
Install so as to provide the required screed
and ground in accordance
with a nominal stucco thickness of 3/4 inch (19
mm) and to create a true
and level surface. (Refer to Plaster
Thickness section)
Install per manufacturers recommendations.
B. Trim accessory and
lath attachment
NOTE:
The installation and pullout resistance of fasteners
shall be in accor-dance
with manufacturers recommendations and safety
requirements.
Fasteners shall be placed in the crotch of the
flange and/or the crotch of
the lath.
The psi of the concrete, how long the concrete
has cured and the
physical condition of the concrete affect the selection
of proper fasteners
for the attachment of trim accessories and lath.
If there is any question on the pullout strength
of the fasteners, sample
testing on the wall is recommended.
Bend lath and continue around corners, a minimum
of 12 inches (300
mm).
Apply so as long dimension of lath is horizontal.
Apply lath taut.
Attachment of lath should be at furring points.
C. Indicate type of stucco
termination trim accessory (casing
bead):
___________________________________________________________________
Indicate name of manufacturer (optional):
_________________________________
D. Attach termination
trim accessory to concrete surface with low-velocity,
power-actuated
pins or drill-and-drive fasteners. Fastener heads minimum
of 3/8-inch (10-
mm) diameter, length of fasteners 3/4 inch (19
mm); spacing of fasteners 8 to 12
inches (200 to 300 mm)
o.c.
E. Indicate the type of
corner reinforcement (corner bead):
______________________
Indicate name of manufacturer (optional):
_________________________________
NOTE:
Selection of proper type in accordance with specified
finish coat.
A welded-wire plastic-nose or PVC corner bead
is recommended if finish
coat is a sand-finish stucco or acrylic finish coat.
Corner reinforcement is recommended at vertical
exterior and slanted
corners.
F. Attach corner reinforcement
to concrete surface with low-velocity, power-actuated
pins or drill-and-drive fasteners. Fastener heads minimum
of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch (19
mm); spacing of fasteners 12 inches
(300
mm) o.c. staggered, or attach to lath with 18-gauge
tie wire, spaced 12 inches (300
mm) o.c. staggered.
G. Indicate the type of
trim accessory joint (control
joint, expansion joint, reveal or
other style): _________________________________________________________
Indicate name of manufacturer (optional):
_________________________________
NOTE:
Trim accessory joints (control
joints) are recommended , but not as
frequently as on framed and sheathed construction. Refer
to section 3.04.
Control joints are recommended for areas greater
than 200 square feet
(18 m 2 ). Maximum recommended
length of a panel is 20 feet (6
m).
Panel size should not exceed a 3-to-1 ratio.
The location of trim accessory joints and the
type are by the architect.
H. Attach trim accessory joints to concrete surface
with low-velocity, power-actuated
pins or drill-and-drive fasteners. Fastener heads minimum
of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch (19 mm); spacing
of fasteners 12 inches (300
mm) o.c.
NOTE:
Attachment method depends on type and function
of trim accessory
joints.
The recommendation is for the control joints
be installed over the
continuous lath, except at specified locations requiring
an expansion-type
trim accessory joint.
I. Installation of expansion
joints requires lath to be cut and attached to both
sides of
the expansion joint flange staggered 12 inches (300
mm) o.c., attach with wire ties or
appropriate fasteners into concrete surface. (Control
joints installed on top of lath.)
NOTE:
Expansion joints are recommended where there
are concrete expansion
joints (construction joints).
J. Install galvanized
self-furring diamond-mesh metal lath, 2.5 or 3.4 pounds
per
square yard (1.4 kg/m 2 or 1.8
kg/m 2 ) to vertical concrete surface (walls).
For
horizontal concrete surfaces (ceilings),
use 3.4-pound-per-square-yard (1.8
kg/m 2 )
self-furring lath.
NOTE:
Lath shall be applied with the long dimension
of sheets horizontal.
Diamond-mesh lath is recommended rather than
other styles of stucco
reinforcement lath because of the smaller size of opening
in the lath
provides for easier and more positive securing of fasteners
into a concrete
surface.
K. Attach lath to concrete
surface with hardened concrete stub nails; low-velocity,
power-actuated pins or drill-and-drive fasteners. Fastener
heads minimum of 3/8-
inch (10-mm) diameter,
length of fasteners 3/4 inch (19
mm).
L. Spacing of fasteners
for 2.5-pound-per-square-yard lath to walls shall be
16 inches
(400 mm) o.c. horizontally
and 7 inches (180 mm) o.c.
vertically. Spacing of
fasteners for 3.4-pound-per-square-inch lath to walls
shall be 24 inches (600 mm)
o.c. horizontally and 6 inches (180
mm) vertically. Spacing of fasteners for lath
to
ceilings shall be 16 inches (400
mm) and 7 inches (180 mm)
o.c.
3.27 Stucco Assembly Attached to Concrete/Application
of Stucco Basecoat
Refer to section 3.39 in
this Stucco Resource Guide.
3.28 Curing of BasecoatRefer to section 3.40.
3.29 Stucco Finish CoatRefer to section 3.41.
3.30 Acrylic Finish CoatRefer to section 3.42.
3.31 Additional Types of FinishesRefer to section
3.43.
3.32 Stucco Assembly Attached to Concrete MasonryRefer
to Stucco Wall Assem-blies
NOTE:
This system is used if a greater thickness of
stucco is required than is
recommended for stucco directly applied or if the concrete
masonry
surface will not provide an adequate bond with the cement
plaster.
A concrete masonry wall must have been cured
in accordance with
industry standards (a minimum
of 30 days) before application of stucco
assembly.
A concrete masonry surface is to be in good condition,
no spalling or
delamination, and no large voids.
Do not tool the mortar joints of the concrete
masonry assembly. It is
recommended to have mortar joints struck flush with
the surface.
A concrete masonry substrate shall be aligned
in accordance with its
application standards.
A. Install trim accessoriestermination trim accessories
(casing beads), corner
reinforcements (corner beads);
trim accessory joints (control
joints) and other
specified accessories in accordance with sections 3.03
and 3.04.
NOTE:
Install per related detail sections of this Stucco
Resource Guide.
Delete trim accessories not applicable to project.
Install per manufacturers recommendations.
Depth (grounds)
of trim accessory to be in accordance with the
thickness of stucco. (Refer to
Plaster Thickness Tables)
Install so as to provide the required screed
and ground in accordance
with a nominal stucco thickness or 3/4 inch (19
mm) and to create a true
and level surface. (Refer to Plaster
Thickness Tables)
B. Trim accessory and
lath attachment
NOTE:
The installation and pullout resistance of fasteners
shall be in accor-dance
with manufacturers recommendations and safety
requirements.
Fasteners shall be placed in the crotch of the
trim accessory flange and/
or the crotch of the lath.
The type and condition of the concrete masonry
surface affect the selection
of proper fasteners for the attachment of trim accessories
and lath.
If there is any question on the pullout strength
of the fasteners, sample
testing on the wall is recommended.
Bend lath and continue around corners, a minimum
of 12 inches (300
mm), or install a corner reinforcement.
Apply so as long dimension or lath is horizontal.
Apply lath taut.
Attachment of lath should be at furring points.
Fasteners shall be placed in the crotch of the
flanges and or the crotch
of the lath.
Spacing of fasteners may depend on type and size
of the concrete
masonry units.
For substrates of concrete masonry units, brick
or tile, it is recom-mended
that the fasteners be placed in the mortar joints.
(This will
minimize damage to the individual units).
C. Indicate type of termination
trim accessory (casing bead/foundation
weep screed):
___________________________________________________________________
Indicate name of manufacturer (optional):
_________________________________
D. Attach termination
trim accessory to concrete masonry surface with hardened
concrete stub nails; low-velocity, power-actuated pins
or drill-and-drive fasteners.
Fastener heads minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch
(19 mm); spacing of fasteners
12 inches (300 mm) o.c.
E. Indicate the type of corner reinforcement (corner
bead): ______________________
and name of manufacturer (optional):
_____________________________________
NOTE:
Corner reinforcement is recommended at vertical
exterior and slanted
corners.
Selection of proper type in accordance with specified
finish coat.
A welded wire plastic-nose or PVC corner bead
is recommended if finish
coat is a sand-finish stucco or acrylic finish coat.
F. Attach corner reinforcement
to concrete masonry surface with hardened concrete
stub nails; low-velocity, power-actuated pins or drill-and-drive
fasteners. Fastener
heads minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch (19 mm);
spacing of fasteners 12 inches (300
mm) o.c. staggered.
G. Indicate type of trim
accessory joint (control joint,
expansion joint, reveal or other
style): ______________________________________________________________
Indicate name of manufacturer (optional):
_________________________________
NOTE:
Control or expansion joints are recommended at
locations of concrete
masonry expansion joints (construction
joints).
Trim accessory joints (control
joints) are recommended, but not as
frequently as for framed construction.
Control joints are recommended for areas greater
than 200 square feet.
Maximum recommended length of a panel is 20 feet (6
m). Panel size
should not exceed a 3-to-1 ratio.
The location of trim accessory joints and the
type are by the architect.
H. Attach trim accessory
joints to concrete masonry surface with hardened concrete
stub nails; low-velocity, power-actuated pins or drill-and-drive
fasteners. Fastener
heads minimum of 3/8-inch (10-mm)
diameter, length of fasteners 3/4 inch (19
mm);
spacing of fasteners 12 inches (300
mm) o.c. staggered.
I. Installation of expansion
joints requires lath to be cut and attached to both
sides of
the expansion joint 12 inches
(300 mm) o.c. staggered, with appropriate fasteners,
into concrete masonry joints.
J. Installation of lath
reinforcement to concrete masonry
NOTE:
Do not begin lathing work until all unsatisfactory
conditions are
resolved.
A water-resistant barrier is not normally required
or recommended for
this stucco assembly. A combination self-furring lath
and water-resistant
barrier (paper-backed lath) is the style of lath recommended
if the
project documents specify a water-resistant barrier
over the concrete
masonry substrate.
Lath shall be applied with the long dimension
of rolls and/or sheets
horizontal.
K. Indicate type of self-furring
lath: _________________________________________
Indicate name of manufacturer (optional):
_________________________________
Refer to section 2.07 for lath selection.
NOTE:
Delete lath types not applicable.
If type of lath is not specified, it is the contractor
installing the lath who
selects the type for the project. Lath selected by contractor
is to be
installed only after it has been approved.
All lath to be in accordance with this Stucco
Resource Guide and its
reference standards. Refer to section 1.04.
L. Attach lath to concrete
masonry surface with hardened concrete stub nails; low-velocity,
power-actuated pins or drill-and-drive fasteners. Fastener
heads minimum
of 3/8-inch (10-mm) diameter,
length of fasteners 3/4 inch (19
mm).
M. Spacing of fasteners for attachment of woven wire
lath, welded wire lath and 2.5-
pound-per-square-yard diamond-mesh lath: 16 inches (400
mm) o.c. horizontally.
For attachment of 3.4-pound-per-square-yard diamond-mesh
lath: 24 inches (600
mm) o.c. horizontally. Vertical attachment of
lath shall be 7 inches (180 mm).
3.33 Stucco Assembly Attached to Concrete Masonry/Application
of Stucco Basecoat
Refer to section 3.39 in this Stucco Resource
Guide.
3.34 Curing of BasecoatRefer to section 3.40.
3.35 Stucco Finish CoatRefer to section 3.41.
3.36 Acrylic Finish CoatRefer to section 3.42.
3.37 Additional Types of FinishesRefer to section
3.43.
3.38 Stucco Assembly to Sheathed ConstructionRefer
to Stucco Wall Assemblies
section details A2 and A3 in this Stucco Resource Guide.
NOTE:
Framed construction refers to a wood framing
assembly or a light-gauge
steel framing assembly with appropriate sheathing.
It is recommended that the minimum size of wood
framing member the
stucco system is going over be 2x4 and standard or better
grade.
It is recommended that the minimum size of steel
framing members be 3
1/2 inches (88 mm) and
a minimum of 20-gauge (.0329)
Open-frame construction is an approved framing
method for attachment
of stucco assembly, but not recommended for best performance.
Exterior sheathing board to have firm contact
with framing members (no
gaps).
Framing assembly (substrate)
to be true, straight and level. Align in
accordance with its application standards.
It is recommended that the wood framing and wood
sheathing board
have a moisture content of less than 19 percent before
starting the scope
of the stucco work.
Stucco is classified as a brittle exterior cladding,
which means the
cement plaster membrane is not flexible. The substrate
to which the
stucco systems is attached must be rigid and a minimum
design
deflection of L/360.
The structure of the building to which the stucco
system is installed can
be load or non-load bearing walls.
It is recommended that the shear value of the
wall to be created by the
structure itself, not the stucco system.
Appropriate exterior sheathing boards over which
to install the stucco
assembly:
1. Exterior gypsum sheathing
2. Glass-mat gypsum sheathing
3. Cementitious backer
board (may require paperback lath)
4. Exterior-grade plywood
5. Oriented strand board
Exterior-grade plywood and oriented strand board
shall be installed with
a minimum of 1/8 inch (3 mm)
gap along all panel edges and ends.
Exterior sheathing boards to be installed per
the manufacturers
recommendations and building code requirements.
Exterior sheathing board, once installed, requires
protection from
climatic conditions, until the installation of the stucco
system.
Do not begin stucco system work until all unsatisfactory
conditions are
resolved.
Sections of flashing or trim accessories that
butt each other (at corners
or another condition) need to be lapped, caulked,
or have a strip of self-adhering
membrane over the joints. This is to prevent moisture
from
getting to the building structure.
A. The stucco contractor
is to install stucco system component flashing
(window head
flashing, expansion joint/weep flashing) only
if this scope of work is indicated in the
project construction documents and stated in the stucco
contractors performance
contract.
NOTE:
Stucco system component flashing does not refer
to standard roof or
other types of building flashing.
Refer to the section details and Scope
of Work Responsibilities section
of this Stucco Resource Guide.
Delete if not applicable to project.
B. Install a water-resistant
barrier WRB as part of the stucco assemby.
Water-resistant
barrier, per F.S. UU-B-790A grade D 60-minute; spunbounded
olefin housewrap for
a stucco system, or an approved weather-resistant barrier
designed for a stucco
system.
NOTE:
It is required to use water-resistant barriers
with all wood or steel framed
structures.
This guide requires two layers of Grade D 60-minute
building paper or
two layers of olefin housewrap over the wood sheathing.
A combination
of these two water-resistant barriers can be used. The
first layer is to be
the housewrap water-resistant barrier.
It is recommended that two layers of water-resistant
barrier be installed
over all types of sheathing boards.
All flashing and water-resistant barrier to be
installed in such a manner
so as to prevent moisture from entering at all edges
(tops and sides).
Do not damage, in any way, the water-resistant
barrier during installa-tion.
If damage occurs, repair before starting the trim and
lathing work
and/or completely replace the water-resistant barrier.
The water-resistant barrier is to be installed
shingle-fashion so that
natural direction of water flow would be over and onto
the next sheet.
Install long dimension horizontal to framing.
Water-resistant barrier shall have horizontal
laps of 2 inches (50 mm)
minimum. Vertical laps shall be 6 inches (150 mm) minimum.
C. Attach water-resistant
barrier to sheathing with small staples so as it is
taut and flat.
Refer to details in the Window Flashing Applications
section of this Stucco
Resource Guide.
D. Install stucco system
trim accessoriesfoundation weep screed, casing
beads,
corner reinforcements (corner
beads), trim accessory joints (control
joints, expansion
joints, reveals) and other specified accessories
in accordance with sections 3.03 and
3.04.
NOTE:
Install per related detail sections of this Stucco
Resource Guide.
Delete trim accessories not applicable to project.
Install per manufacturers recommendations.
The depth (grounds)
of trim accessory to be in accordance with the
thickness of stucco. (Refer to
Plaster Thickness Tables)
Install so as to provide the required screed
and ground in accordance
with nominal stucco thickness requirements. (Refer
to Plaster
Thickness section.)
Install so as to produce a true and level surface
for the cement plaster.
E. Trim accessory and
lath attachment
NOTE:
The type and condition of the sheathing board
and framing members
affect the selection of proper fasteners for the attachment
of trim
accessories and lath.
The installation and pullout resistance of fasteners
shall be in accor-dance
with manufacturers recommendations and safety
requirements.
Fasteners shall be placed in the crotch of the
trim accessory flange and/
or the crotch of the lath.
If there is any question on the pullout strength
of the fasteners, sample
testing on the wall is recommended.
The same fasteners can be used as a combination
attachment for trim
accessories and lath (and in some construction, the
sheathing board).
Lath shall be applied with long dimension of
the sheets or rolls
horizontal (perpendicular) to framing members. Apply
lath taut.
Bend lath and continue around corners to next
framing member and/or
corner reinforcement.
Attachment of lath should be at furring points.
Thickness of sheathing board or boards dictates
the length of fasteners.
Fasteners to penetrate into wood or steel framing
members. Attachment
into only the sheathing board is not recommended.
Fasteners to penetrate a minimum of 3/4 inch
(19 mm) into wood
framing members.
The thickness of sheathing boards of plywood
and oriented strand board
does not make up part of the minimum 3/4-inch (19-mm)
fastener
penetration requirement.
Fasteners to be centered on flange (ends)
or framing member. A
minimum of 3/8 inch (10 mm)
from edge. Both legs of staple to penetrate
framing member.
Fasteners to penetrate a minimum of 2 full threads
past the steel framing
member flange.
All types of fasteners shall bear tight against
attachment item.
Construction methods and design (layout)
may dictate that some
fasteners only penetrate into sheathing board in order
to attach trim
accessory.
Sheathed framed construction with vertical trim
accessory joints that
require the lath to be terminated
(cut) and installed on top of the flanges
shall be placed at framing member locations. Lath shall
be attached with
appropriate fasteners through the trim accessory flange,
sheathing and into
the framing member. The lath/flange on each side of
the trim accessory
joint is recommended to be attached to a framing member.
Double framing
supports may be required at these locations. This condition
does not
pertain to control joints installed over continuous
lath.
F. Indicate type of termination-at-foundation
trim accessory (foundation weep
screed,
as required by Building Code):___________________________________________
Indicate name of manufacturer (optional):
_________________________________
NOTE:
Refer to Termination at Foundation
detail section of this Stucco
Resource Guide.
Foundation weep screeds and in some design details
casing beads can
serve as a termination for the stucco at the building
foundation area.
Building codes require a foundation weep screed.
Finished edge of stucco surface to be no lower
than 4 inches (100 mm)
from finished grade or 2 inches above a hard surface.
G. Fasteners for attachment
of trim accessories, foundation trim and lath
NOTE:
Refer to section 3.38-E.
Length of fasteners depends on thickness of sheathing
boards.
Stucco contractor has the option of selecting
appropriate fasteners from
list below.
Wood-sheathed framing:
1. Roofing nails: 11-gauge
7/16-diameter head 1 1/2 inches long (i.e.,
1/2 inch
wood sheathing)
2. Staples: 16-gauge
3/4-inch crown 1 3/8 long (i.e.,
1/2 inch wood sheathing)
3. Type W screws: wafer
head 1 1/2 inches long (i.e.,
1/2 inch wood sheathing)
Sheathed steel framing:
1. Type S screws: wafer
head self-drilling 1 inch (25
mm) long (i.e., 1/2 inch
sheating)
H. Indicate type of foundation
trim accessory (foundation weep
screed or casing bead):
___________________________________________________________________
Indicate name of manufacturer (optional):
_________________________________
I. Attach foundation trim
accessory to building structure, with appropriate fastener
selected from list in section 3.38-G. Spacing of fasteners
12 inches (300 mm) o.c.
NOTE:
Refer to the Termination at Foundation
detail section of this Stucco
Resource Guide.
J. Indicate type of termination
trim accessory (casing bead):_____________________
Indicate name of manufacturer (optional):
_________________________________
K. Attach termination
trim accessory to building structure, with appropriate
fastener
selected from list in section 3.38-G. Spacing of fasteners
12 inches (300 mm) o.c.
NOTE:
Refer to detail sections of this Stucco Resource
Guide.
L. Indicate type of corner reinforcement (corner bead):
_________________________
Indicate name of manufacturer (optional): _________________________________
NOTE:
Corner reinforcement is recommended at vertical
exterior and slanted
corners.
Selection of proper type in accordance with specified
finish coat.
A welded wire plastic-nose or PVC corner bead
is recommended if finish
coat is a sand-finish stucco or acrylic finish coat.
M. Attach corner reinforcement to building structure,
with appropriate fastener selected
from list in section 3.38-G, or attach to lath with
18-gauge tie wire. Spacing of
fasteners 12 inches (300 mm)
o.c. staggered.
NOTE:
Refer to the Corners detail section
of this Stucco Resource Guide.
N. Indicate the type of trim accessory joint (control
joint, expansion joint, reveal or
other style): _________________________________________________________
Indicate name of manufacturer (optional):
_________________________________
O. Attach trim accessory
joints to building structure, with appropriate fastener
selected
from list in section 3.38-G. Spacing of fasteners 12
inches (300 mm) o.c. staggered.
NOTE:
Refer to Trim Accessory Joints detail
section of this Stucco Resource
Guide.
Joints are recommended if the area is 150 to
180 square feet (14 to 17
m 2 ). Maximum recommended length of a panel
is 18 feet (6 m). Panel
size should not exceed a 3-to-1 ratio.
The location of trim accessory joints and the
type are by the architect.
The design layout of the trim accessory joints
and the location of framing
members may require the control joints to be attached
to the sheathing
and/or attached with tie wire to the lath.
The application of sealants is recommended in
conjunction with the
installation of trim accessory joints. Refer to section
3.04 and details in
the Trim Accessory Joints section of this
Stucco Resource Guide.
A continuous (unbroken)
water-resistant barrier is required behind all
trim accessory joints.
Control joints are the type of trim accessory
joints recommended for
installation over continuous (unbroken)
lath. Expansion joints and
reveals are types of trim accessory joints which require
the lath to be
broken behind the joint.
If attachment of control joint is to lath or
other trim accessories, use 18-
gauge wire tie 12 inches (300
mm) o.c. to each flange, staggered.
Aluminum and/or PVC reveals require that when
the lath is installed
over the flange, it totally covers it. The welded wire
and woven wire lath
shall be installed so as the crotch of the lath is over
the flange.
P. Installation of expansion
joints and reveals requires lath to be cut and attached
to
both sides of the joint flange.
Q. Indicate type of self-furring
lath: _________________________________________
Indicate name of manufacturer (optional):__________________________________
(Refer to section 2.07 for lath
selection.)
NOTE:
If type of lath is not specified, the contractor
installing the lath selects
the type for the project. Lath selected by contractor
is to be installed
only after it has been approved.
Over sheathing board, lath must be self-furring
type and or use furring
fasteners.
It is recommended that paperback lath not be
used on framed sheathed
construction. Installing the water-resistant barrier
separate from the
lath installation provides a better flashing method
and a uniform
thickness of the stucco. On vertical open-frame construction,
paperback
lath or line wire and paper are required.
R. Attach lath to building
structure, with appropriate fastener selected from list
in
section 3.38-G.
NOTE:
Refer to detail section of this Stucco Resource
Guide.
Install lath with long dimension of sheets/rolls
horizontal, perpendicular
to framing members.
Install so overlapping areas are uniform and
per manufacturers
recommendations and building code requirements.
Install so as lath is level, flat and taut.
Bend lath and continue around corners to next
framing member or
install corner beads..
S. For attachment of
2.5-pound-per-square-yard diamond-mesh lath, the spacing
of
framing studs shall be 16 inches (400
mm) o.c. For attachment of woven wire
lath, welded wire lath and 3.4-pound-per-square-yard
diamond-mesh lath, the
spacing of framing studs shall be 24 inches
(600 mm) o.c. Vertical
fasteners for
attachment of all lath to studs shall be 6 inches (150
mm) o.c. (fasteners to
pentrate
into framing supports studs).
NOTE:
Refer to section 3.36 on trim accessory and lath
attachment.
All spacing is maximum.
3.39 Application of Stucco Basecoat
NOTE:
Verify that trim accessories and lath are properly
secured.
Verify trim accessories and lath are installed
so as to provide proper
screeds, thickness and alignment for the plastering
operation.
Do not begin plastering work until unsatisfactory
conditions are
resolved.
Cement plaster can be applied by trowel or machine.
Apply basecoat to entire wall panel and/or section
without interruption
or cold joints.
Install stucco basecoat in accordance with the
requirements and
references in this Guide Specification and the project
construction
documents.
A. Indicate the permissible
mix number and its proportions to be used for the basecoat:
___________________________________________________________________
Refer to Section 2.15.
NOTE:
Delete basecoat mixes not applicable to this
project.
Do not change selected mix or proportions after
plastering operation has
started.
Measurement of ingredients (materials
of the mix) to be done with
devices of known volume, accurate, and successive batches
proportion-ally
alike.
Use only enough mix water to make plaster a workable
consistency.
Admixtures are for improving the basecoat mix
or enhancing the plaster
application. Use products manufactured strictly for
this purpose and in
accordance with manufacturers recommendations.
B. Apply stucco first
(scratch) coat
in a nominal thickness of 3/8 inch (10
mm).
Refer to Plaster Thickness Tables in this Stucco Resource
Guide. First coat to
completely embed the lath. First coat to be thick enough
to go beyond lath so as to
allow for scoring of cement plaster surface.
NOTE:
Scoring of the first coat should be uniform and
shallow, 1/8 inch (3 mm).
C. Apply stucco second (brown)
coat in a nominal thickness of 3/8 inch (10
mm)
over stucco first coat. Second coat thickness to bring
the combined basecoats (first
and second) thickness to a nominal thickness
of 3/4 inch (19 mm). (Refer to
Plaster
Thickness Tables).
NOTE:
Apply second coat over a damp first coat. If
required, apply a fine spray
of clean water, so as to dampen only. Do not saturate.
Allow water
sheen to disappear before applying the second coat.
D. Apply the second coat
with sufficient material and pressure to ensure a tight
uniform
bond to the first coat.
E. The double-back
method of applying successive coats is recommended.
This
procedure has little or no delay between applying the
second coat over the first coat.
NOTE:
Advantages of this method are that it creates
a better bond between the
two coats, it provides for uniform and better curing
of the basecoat and it
reduces delay on the project.
Apply second coat as soon as the first coat is
rigid enough to receive it.
This method is not recommended for open-frame
construction (vertical
and horizontal surfaces).
F. Rod the second coat
to a true, even plane, filling surface defects with
cement plaster.
G. Trowel-float the second
coat surface uniformly.
NOTE:
The floating process densifies the basecoat and
provides a proper surface
for the finish coat application.
Float the basecoat after it has set and when
moisture is still present in it.
(The float should not adhere to
the surface that is to be worked)
Floating the basecoat that is to receive an acrylic
finish coat is critical
because of the thickness of this finish.
3.40 Curing of Basecoat
A. Climatic conditions
dictate the need for moist-curing.
NOTE:
Cement plaster gains its strength in the first
day or two.
Moist-curing enables the cement materials to
hydrate properly and the
stucco membrane to reach its desired physical properties.
Moist-curing helps prevent craze cracking.
Cement plaster basecoat to cure for a minimum
of seven days before
starting finish coat application. Moist cure for the
first two days.
B. Moist-curing is recommended
when the ambient temperature is 77....F (25....C)
or
higher and/or when the ambient relative humidity is
below 70 percent and the
conditions are windy.
NOTE:
Moist-cure in the morning and/late afternoon
for a period of two days.
Moist-cure with a fine mist of clean water; do
not saturate.
Moist-cure only after the basecoat has set and
is hard.
Extreme weather conditions may require plastic
sheets to retard
evaporation.
C. The stucco basecoat
should be protected from freezing for a period of 24
hours after
application.
NOTE:
Do not moist-cure if basecoat is subject to freezing.
Do not use frozen materials in mix.
Do not apply cement plaster to a surface that
is frozen or contains frost.
3.41 Stucco Finish Coat
NOTE:
Stucco finish coat in this specification
refers to the cement plaster
finish of which there are two types: (1)
Job-site stucco finish coat, and (2)
manufactured stucco finish coat.
For colored (integral color)
stucco finish coat, the use of a manufactured
stucco finish is recommended.
It is recommended that the lighter tones of color
(pastel colors) be used
for mineral stucco finishes.
Stucco finish coat color uniformity cannot be
guaranteed because of a
variety of uncontrollable factors (suction
of basecoat and the application
of the finish coat will vary with climatic conditions).
Manufactured
stucco finish coat will produce the most consistent
color.
Time necessary between the completion of basecoat
(brown coat) and the
application of finish coat will vary with climatic conditions.
It is recommended that the basecoat which is
to receive the finish coat
cure for a minimum of seven days.
(This does not pertain to section 3.14
Finish Coat Direct to Concrete)
For job-site finish coat, it is recommended that
the coloring agents be
from a stucco finish-coat manufacturer.
A. Stucco basecoat (or concrete
surface) is required to be in a proper condition
before
application of stucco finish coat or acrylic finish
coat.
NOTE:
Do not apply finish coat until all irregularities
in the basecoat have been
addressed.
B. Apply stucco finish
coat to damp cement plaster basecoat.
NOTE:
Dampen the basecoat with a mist of clean water
to obtain uniform
suction. Do not saturate: there should not be any visible
water on the
surface when the finish coat is applied.
C. Apply stucco finish
coat in a nominal thickness of 1/8 inch (3
mm). (Refer to Stucco
Thickness Tables).
D. Apply stucco finish
with sufficient material and pressure to ensure a tight
bond with
basecoat (brown coat) or concrete surface.
E. Apply stucco finish
to a uniform thickness and in a consistent finish in
accordance
with style of finish specified.
NOTE:
Apply finish coat starting from the top of the
wall surface and work
down.
Apply finish coat with no interruptions; no cold
joints.
Apply finish coat so there are no scaffold
lines or joint stains.
F. Moist-curing of finish
coat is not recommended, except in severe climatic conditions
(e.g., extreme heat, strong winds
and low relative humidity).
NOTE:
Moist-curing of the stucco finish coat can cause
discoloration.
G. Indicate the type of stucco finish coat:
Job-site mixed stucco finish __________________________________________
Manufactured stucco finish __________________________________________
NOTE:
Delete the type of finish not applicable
H. Indicate the style of stucco finish _________________________________________
(Refer to 3.41-I)
NOTE:
Smooth trowel finish is not recommended when
the material is cement
plaster.
Very heavy textures may have to be applied in
the basecoat because a
nominal stucco finish coat is not thick enough.
It is recommended that a sample of the finish
coat be applied to a wall at
the project site if possible.
Provide style and color sample of stucco finish
coat for approval before
starting the application of finish coat. Delete if not
applicable.
The approved sample to be maintained on project
site until the scope of
stucco work is completed and approved.
Use only enough water in stucco finish coat mix
to make it workable.
I. Styles of stucco finish
1. Sand Float Finish
(fine, medium or course)
2. Machine Dash Finish
(light/medium/heavy)
3. Knockdown Dash Finish
4. Lace Finish
5. Light Comb Finish
6. English Finish
7. Frieze Finish
8. Spanish Finish.
NOTE:
Delete finish styles not applicable.
J. Indicate the color
of stucco finish ________________________________________
3.42 Acrylic Finish Coat
NOTE:
The acrylic finish to be 100-percent acrylic
polymer base.
Acrylic finish coat and manufacturer to be recommended
by NWCB and/
or regional Wall and Ceiling Association.
Basecoat of cement plaster that is to receive
an acrylic finish coat shall
have been floated and/or have a stucco sand-finish.
Do not apply finish until all irregularities
in the basecoat or concrete
surface have been addressed.
A. Indicate style of acrylic finish: __________________________________________
Indicate color of acrylic finish: __________________________________________
Indicate approved manufacturers: ________________________________________
NOTE:
Refer to manufacturer for different styles and
color selection.
B. Apply acrylic finish
over stucco basecoat (brown coat) or concrete surface
a
minimum of 1/16 inch (2 mm) dry thickness.
NOTE:
Acrylic finish to be applied per the manufacturers
recommendations.
Stucco basecoat shall be free of efflorescence.
Apply acrylic finish coat
only at an ambient temperature of 40 °F (4 °C)
and rising. This
temperature is recommended for a minimum of 24 hours
after applica-tion.
Acrylic finish shall maintain a wet edge at all
times. The finished
surface shall have no scaffold or stain lines.
Protect finished surface from climatic conditions
until dry.
It can be difficult to achieve a uniform color
using a spray-applied acrylic
finish. Therefore, it is recommended that a troweled
application of the
acrylic finish be applied first.
Do not moist-cure acrylic finish.
C. Apply acrylic finish
coat with sufficient material to uniformly and completely
cover
the basecoat.
3.43 Additional Types of Finishes
NOTE:
To be approved by NWCB.
A. Factory-mixed 100-percent
acrylic-based elastomeric finish
B. High-quality exterior
acrylic paint.Portland Cement
NOTE:
Applied per manufacturers recommendations
over a stucco finish or
acrylic finish.
C. High-quality exterior
elastomeric paint
NOTE:
Applied over a stucco finish coat or acrylic
finish coat.
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