SECTION 07480
DUROCK EXTERIOR CEMENT BOARD SYSTEMS
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Use this guide specification to specify DUROCK Brand
Exterior
Cement Board systems by U.S. Gypsum Co. Review a
copy of USG
publication SA-700 before editing specification.
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PART 1 - GENERAL
GENERAL DOCUMENTS
General and Supplementary Conditions of Contract
as well as
Drawings and general provisions of Contract and Division
1
Specification section, apply to work of this section.
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VERSATILE DUROCK EXTERIOR CEMENT BOARDS CAN BE USED
WITH A WIDE
RANGE OF CONSTRUCTION MATERIALS, METHODS, AND FINISHES.
EDIT
BELOW TO DESCRIBE SCOPE OF THIS SECTION AND TO COORDINATE
WITH
OTHER SECTIONS.
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This Section includes exterior wall systems constructed
of cement
board building panels and related materials, including:
Light gage steel framing.
Exterior finish.
Setting and grouting materials for ceramic tile and
thin brick
veneer.
Insulation.
Water barrier membrane.
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GENERAL REQUIREMENTS FOR THIN BRICK, SUCH AS TYPE,
SIZE, AND
COLOR, CAN BE SPECIFIED IN THIS SECTION OR IN DIVISION
4. BUT TO
ASSURE COMPATIBILITY WITH DUROCK CEMENT BOARD, INSTALLATION
MATERIALS AND METHODS SHOULD BE SPECIFIED IN THIS
SECTION.
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Thin brick veneer is specified in Division 4 Section
"Unit
Masonry".
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WHENEVER POSSIBLE, STEEL FRAMING FOR CEMENT BOARD
BUILDING PANELS
SHOULD BE SPECIFIED IN SAME SECTION AS BUILDING PANELS
TO ASSURE
SYSTEM COORDINATION. SEE USG PRODUCT LITERATURE
FOR STEEL
FRAMING SYSTEMS.
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Light gage steel framing is specified in Division
5 Section
"Cold-Formed Metal Framing".
Wood framing is specified in Division 6 Section "Rough
Carpentry".
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FIRE SAFING MAY BE REQUIRED BETWEEN EDGES OF FLOOR
SLABS AND
CURTAIN WALL TYPE CONSTRUCTION. FOR ADDITIONAL INFORMATION,
SEE
USG PRODUCT LITERATURE FOR THERMAFIBER FIRE SAFING
INSULATION.
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Fire safing insulation is specified in Division 7.
Flashings are specified in Division 7 Section "Flashing
and Sheet
Metal".
Sealants for joints in wall system and perimeter
sealing are
specified in Division 7 Section "Joint Sealers".
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VERIFY SUBSTRATE REQUIREMENTS WITH AGGREGATE COATING
MANUFACTURER.
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Stone aggregate in epoxy matrix is specified in Division
9
Section "Aggregate Coatings".
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SEE USG PRODUCT LITERATURE FOR COMPATIBLE DRYWALL
PRODUCTS.
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Gypsum drywall for interior finishes of exterior
walls is
specified in Division 9 Section "Gypsum Drywall".
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GENERAL REQUIREMENTS FOR TILE, SUCH AS TYPE, SIZE,
AND COLOR, CAN
BE SPECIFIED IN THIS SECTION OR DIVISION 9. BUT
TO ASSURE
COMPATIBILITY WITH DUROCK CEMENT BOARD, INSTALLATION
MATERIALS
AND METHODS SHOULD BE SPECIFIED IN THIS SECTION.
SEE USG PRODUCT
LITERATURE FOR DURABOND TILE SETTING AND GROUTING
PRODUCTS WHICH
ARE COMPATIBLE WITH MATERIALS SPECIFIED IN THIS SECTION.
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Ceramic tile veneer is specified in Division 9 Section
"Tile".
QUALITY ASSURANCE
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DELETE OR MODIFY FIRE-RESISTANCE RATING AS REQUIRED
FOR PROJECT.
OTHER APPLICABLE UL DESIGNS INCLUDE U457, U458, U459,
U473 and
U474. EDIT SECTION TO CONFORM TO SELECTED UL DESIGN
REQUIREMENTS.
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Fire-Resistance Rating: As indicated by reference
to design
designation in UL "Fire Resistance Directory";
tested per ASTM E
119.
Steel Framing: UL Design U442.
Wood Framing: UL Design U329.
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USG CAN NOT ACCEPT RESPONSIBILITY FOR PERFORMANCE
OF DUROCK
EXTERIOR CEMENT BOARD OR OTHER DUROCK COMPONENTS
WHEN USED WITH
PRODUCTS WHICH HAVE NOT BEEN TESTED AND APPROVED
BY UNITED STATES
GYPSUM COMPANY AS PART OF THE DUROCK EXTERIOR CEMENT
BOARD
SYSTEM.
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Unit Responsibility: Obtain panel system components
from a
single manufacturer, or from manufacturers recommended
by the
prime manufacturer of cement boards.
SUBMITTALS
Product Data: Submit manufacturer's product literature,
specifications, and installation instructions for
each type of
component specified, including other data as may
be required to
show compliance with these specifications.
Samples: Submit samples as listed below.
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EDIT BELOW TO SUIT PROJECT.
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Cement Board: 12 x 12 inches, apply exterior finish
to one side
in color and texture required.
Metal Framing: 12 inches length, each type.
Fastener: Each type.
Reinforcing Tape: 12 inches length.
Membrane: 12 x 12 inches.
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EDIT BELOW AS REQUIRED. DELETE IF COLORS ARE PRESELECTED
AND
SCHEDULED.
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Grout Samples for Initial Selection Purposes: Submit
samples of
grout and exterior finish showing full range of colors
available.
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RETAIN BELOW IF REQUIRED TO COORDINATE WITH TILE
SUBMITTAL
REQUIREMENTS.
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Grout Samples for Verification Purposes: Submit
samples of grout
applied to tile sample boards specified in Division
9 Section
"Tile".
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SPECIFY ASSEMBLY SAMPLE ONLY IF REQUIRED BY SPECIAL
CONDITIONS.
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Assembly: Provide 2 x 2 feet sample of assembled
panel system,
containing all component materials as specified in
this section
and representative veneer and finish applications
as specified
for the completed system; cut-away construction to
illustrate
construction and attachments.
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DELETE BELOW IF NOT REQUIRED
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Certification for Fire Test Performance: Submit
manufacturer's
fire test report or written certification that assembly
systems
have been tested by an independent laboratory and
comply with
required fire test performance.
DELIVERY, STORAGE AND HANDLING
Deliver materials in original unopened packages,
containers, or
bundles bearing brand name and identification of
manufacturer or
supplier.
Store materials in an enclosed shelter in manner
to keep them
dry, protected from weather, surface contamination,
and damage
from construction traffic and other causes. Neatly
stack cement
boards flat to prevent sagging. Protect emulsion
products from
freezing.
Handle cement boards to prevent damage to edges,
ends or sur-
faces. Protect metal framing members from being bent
or damaged.
If gypsum boards are utilized, handle and store similar
to cement
boards.
PROJECT CONDITIONS
Environmental Requirements, General: Comply with
requirements of
referenced products application standards and recommendations
of
manufacturer, for environmental conditions before,
during and
after application of materials.
Weather Protection: Do not apply finishes to exterior
cement
board if surface is wet, frozen, or contains frost;
or when
ambient temperature is below 45 deg F (13 deg C).
For at least
24 hours after application of finish materials, maintain
temperature at 45 deg F (13 deg C) minimum and protect
from
exposure to rain and moisture.
PART 2 - GENERAL
MANUFACTURER
Subject to compliance with requirements, provide
products
manufactured or supplied by United States Gypsum
Company, unless
otherwise indicated.
STEEL FRAMING MATERIALS
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FRAMING IS ALSO AVAILABLE IN SOME AREAS WITH ALUMINIZED
FINISH
PER ASTM A 463 OR WITH AN ALUMINUM-ZINC ALLOY COATING,
PER ASTM A
792.
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Steel Framing - General: Uncoated steel thickness
shall comply
with ASTM A 568. Hot-dipped galvanize to comply
with ASTM A 525
G60. Fabricate to comply with ASTM C 645.
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SHOW RUNNER AND STUD DEPTH, TYPE, AND GAGE ON DRAWINGS
OR SPECIFY
IN PARAGRAPHS BELOW.
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Runners: Unimast Types CR and UR, 33 ksi minimum
yield strength,
gage as shown on drawings, depth to match studs.
Studs: Size and gage as shown on drawings; provide
following
types:
Unimast Type SJ, 40 ksi minimum yield strength.
Unimast Type ST, 33 ksi minimum yield strength.
Steel Framing Fasteners: Type S-12 self-drilling
screws, 1/2
inch long pan head type or 5/8 inch long low profile
head type
with CLIMASEAL corrosion resistant finish.
Anchors: Provide types required to securely attach
framing to
adjacent construction.
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FOLLOWING ARE EXAMPLES ONLY. SPECIFY FASTENERS SUITABLE
FOR
CONDITIONS OF USE.
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Concrete: 5/32 inch diameter low-velocity power-driven
fastener
with 1-1/2 inches minimum penetration.
Steel: Self-drilling screws.
Plywood Subfloor and Steel Joist Framing: Type S-12
pilot-point
screws, 1-15/16 inches long.
Curtain Wall Clip: Unimast Curtain Wall Slide Clip.
Framing Accessories: Provide bracing, blocking,
metal angles,
and other accessories as shown on drawings and as
required for
application intended.
CEMENT BOARD MATERIALS
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DUROCK EXTERIOR CEMENT BOARD CAN ALSO BE USED AS
AN INTERIOR TILE
BACKER BOARD, SEE USG PRODUCT FOLDER SA-932.
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Cement Board: DUROCK Exterior Cement Board; aggregated
portland
cement board with polymer-coated, woven glass-fiber
mesh embedded
in front and back surfaces.
Thickness: 1/2 inch minimum.
Size: 4 feet wide x 8 feet long.
Faces: Smooth on one side, coarse on other side.
Edges: Formed, smooth, reinforced edges; square
cut ends.
Weight:3 pounds per square foot maximum.
Flexural Strength: 1000 psi minimum per ASTM C 947.
Water Absorption: 10% by weight max., 24 hr. per
ASTM C 948.
Nail Pull Resistance: 125 lbs. min., 0.4 inch head
diameter, wet
or dry, per ASTM C 473.
Freeze/Thaw: 100 cycles with no deterioration per
ASTM C 666
Procedure A.
Flame Spread, Smoke Developed: 5, 0 per ASTM E 84.
Cement Board Fasteners: DUROCK Screws, wafer head,
self-drilling
screw with CLIMASEAL corrosion resistant finish.
Metal Framing: Type S-12, 1-1/4 inches or 1-5/8
inches.
Use 1-5/8 inches fasteners when cement board is installed
over
1/2 inch maximum rigid foam insulation.
Wood Framing: Type S, 1-5/8 inches.
Joint Reinforcement: As follows:
Reinforcing Tape: DUROCK Exterior Tape, 2 inches
wide, polymer
coated woven glass-fiber mesh with pressure-sensitive
adhesive on
one side.
Joint Compound: DUROCK Exterior Basecoat; ready-to-mix
portland
cement mortar containing dry latex polymers; gray.
Surface Control Joint: SHEETROCK Zinc Control Joint
No. 093,
roll-formed zinc.
Trim Accessories: DUROCK corner beads and 1/2 inch
trim angles;
zinc alloy.
Water Barrier: TYVEK HOUSEWRAP, high density polyethylene
fiber
water and air barrier, manufactured by E.I. duPont
de Nemours &
Company.
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NO. 15 ASPHALT FELT CAN BE SPECIFIED INSTEAD OF TYVEK.
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Staples: 1/2 inch crown, 3/8 inch leg; galvanized.
INSULATION
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SHOW INSULATION THICKNESS OR R-VALUE ON DRAWINGS
OR SPECIFY
BELOW. INSULATION CONSIDERATIONS INCLUDE THERMAL
REQUIREMENTS,
VAPOR RETARDER REQUIREMENTS, FIRE PERFORMANCE CHARACTERISTICS,
AND CONDITIONS OF USE.
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Blanket Insulation: THERMAFIBER Mineral Fiber Insulation,
thickness or R-value as shown on drawings.
THERMAFIBER Sound Attenuation Fire Blankets (SAFB);
ASTM C 665,
Type I; 15 flame spread, 0 smoke developed.
THERMAFIBER Fire Safety FS-15 Insulating Blankets;
ASTM C 665,
Type I; 15 flame spread, 0 smoke developed.
THERMAFIBER Fire Safety FS-25 Insulating Blankets,
foil faced;
ASTM C 665, Type III; 25 flame spread, 5 smoke developed.
THERMAFIBER Aluminum Foil-Faced Blankets, foil faced
vapor
retarder with nailing flanges; ASTM C 665, Type III.
Fire Safing Insulation: THERMAFIBER Safing Insulation
and steel
safing clips.
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RIGID INSULATION MAY BE REQUIRED WHEN USING DUROCK
EXTERIOR
FINISH TO HELP CONTROL POTENTIAL "SHADOWING"
ON SURFACE OF WALL
DUE TO CONDENSATION. SPECIFY TYPE OF RIGID FOAM
INSULATION
REQUIRED. DO NOT USE EXPANDED POLYSTYRENE (EPS OR
"BEAD BOARD")
OR EXCEED 1/2 INCH THICKNESS.
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EXTERIOR FINISH MATERIALS
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INCLUDE THIS ARTICLE FOR DUROCK EXTERIOR FINISH,
A STUCCO-LOOK,
WEATHER RESISTANT, TEXTURED COATING.
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Base Coat: DUROCK Exterior Basecoat; ready-to-mix
portland
cement mortar containing dry latex polymers; gray.
Textured Coating: DUROCK Exterior Finish; acrylic
coating, ready
mixed; fine or coarse formulation and color as selected
from
manufacturer's standards.
Mixing: Mix in accordance with manufacturer's instructions.
Water shall be clean and potable.
SETTING AND GROUTING MATERIALS
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INCLUDE THIS ARTICLE IF CERAMIC TILE OR THIN BRICK
VENEER
FINISHES ARE USED. WHITE MORTAR AND GROUT ARE ALSO
AVAILABLE.
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Skim Coat and Mortar: DUROCK or DURABOND Latex Fortified
Mortar;
ready-to-mix, thin-set mortar containing dry latex
polymers,
especially formulated for use with DUROCK Exterior
Cement Board;
gray or white.
Grout: DUROCK Latex Fortified Grout; ready-to-mix
grout
containing dry latex polymers, especially formulated
for use with
DUROCK Exterior Cement Board; gray or white.
Mixing: Mix in accordance with manufacturer's instructions.
Water shall be clean and potable.
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SPECIFICATIONS FOR TILE, THIN BRICK, AGGREGATE COATING,
OR OTHER
FINISH MATERIALS CAN BE INSERTED HERE. COORDINATE
WITH WORK
SPECIFIED IN OTHER SECTIONS.
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PART 3 - EXECUTION
GENERAL
Comply with manufacturer's printed installation instructions
for
products and applications indicated, except where
more stringent
requirements apply.
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RETAIN BELOW IF RATED CONSTRUCTION IS REQUIRED.
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Conform to construction requirements of tested assemblies
used to
demonstrate required fire resistance.
EXAMINATION
Coordinate work of this section with building structural
system;
ensure anchorage provisions have been installed to
receive cement
board system.
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RETAIN BELOW IF WOOD OR METAL FRAMING ARE SPECIFIED
IN ANOTHER
SECTION.
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Examine framing for compliance with requirements
and conditions
affecting work of this section. Do not proceed with
installation
until unsatisfactory conditions have been corrected.
STEEL FRAMING INSTALLATION
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SPACING FOR RUNNER ATTACHMENT AND STUDS SHOULD BE
SHOWN ON
DRAWINGS OR SPECIFIED BELOW. SPACING SHOULD BE DETERMINED
BY
ARCHITECT OR ENGINEER IN ACCORDANCE WITH GUIDELINES
CONTAINED IN
USG PRODUCT LITERATURE. WHERE REQUIRED BY POTENTIAL
DEFLECTION
OF BUILDING STRUCTURE, INDICATE ADDITIONAL REQUIREMENTS
TO ALLOW
FOR "FLOATING" CONSTRUCTION OF EXTERIOR
WALLS.
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Runners: Accurately align and secure to base and
head with power
driven fasteners spaced as shown on drawings.
Studs: Position vertically in runners at spacing
shown on
drawings. Anchor each stud to runner with four screws,
two at top
and two at bottom, with one screw in each flange.
At building control joints that extend through wall,
provide
breaks in top and bottom runner track. Install 1-1/2
inch cold-
rolled channel alignment stabilizers spaced maximum
5 feet o.c.
vertically. Place channels through holes in stud
web of the first
two adjacent studs on both sides of the joint, and
securely
attached to the first adjacent stud on either side
of the joint.
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SHOW DETAILS OF PENETRATIONS ON DRAWINGS.
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At wall penetrations such as windows and doors, provide
additional reinforcement at header, sill, and jambs
to transfer
and support loads.
Provide framing accessories and curtain wall clips
as shown and
drawings and as required for conditions of use.
RIGID FOAM INSULATION
Install rigid foam insulation over framing with fasteners
adequate to hold in place until covered by cement
boards. Butt
ends and edges and stagger joints.
WATER BARRIER
Install water barrier in shingle-like manner beginning
at bottom
of
wall. Overlap edges 2 inches.
CEMENT BOARD
Apply cement board panels with coarse side towards
exterior and
with ends over supports. Stagger end joints in successive
courses. Fit ends and edges closely, but not forced
together.
Fasten cement board panels to framing with specified
fasteners.
Space 8 inches o.c. at walls, 6 inches o.c. at soffits.
Drive
fasteners in field of panels first, working towards
ends and
edges. Hold panel in firm contact with framing while
driving
fasteners. Locate perimeter fasteners at least 3/8
inch from ends
and edges. Drive screws so heads are flush with surface
of
panels. Provide firm panel contact with framing.
Reinforcing Tape: Apply over joints and corners
except where
corner beads or control joints are used. Do not
overlap.
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USE TRIM ACCESSORIES WITH DUROCK EXTERIOR FINISH
AND, IF
REQUIRED, WITH AGGREGATE COATING. OPTIONAL TRIM
ANGLES CAN BE
USED AT PERIMETER OF CEMENT BOARD PANEL SYSTEM.
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Trim Accessories: Install corner beads at outside
corners.
Install trim angles where shown on drawings. Fasten
with
staples.
Vent soffits as shown on drawings.
EXPANSION AND CONTRACTION
Provide surface control joints where shown on drawings
and as
follows:
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ADJUST LISTING BELOW TO PROJECT.
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Wall abuts a structural element or dissimilar wall
or surface.
Construction changes within the plane of the wall.
At control or expansion joints in underlaying construction.
20 feet o.c. maximum for DUROCK Exterior Finish system;
16 feet
o.c. maximum for tile and thin brick finishes.
Separate cement boards behind control joints. Where
vertical and
horizontal control joints intersect, vertical control
joints
shall be continuous and horizontal control joints
shall abut.
Apply sealant to splices, terminals, and intersections
of control
joints as specified in Division 7 Section "Joint
Sealers".
BLANKET AND SAFING INSULATION
Blanket Insulation: Install to completely fill stud
cavity to
thickness required. Tightly butt ends and sides
of blankets.
Staple nailing flanges to sides of wood studs and
plates, do not
attach to face of framing.
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RETAIN ABOVE WITH USING WOOD FRAMING AND INSULATION
BLANKETS WITH
NAILING FLANGES.
RETAIN BELOW IF USING INSULATION BLANKETS WITH VAPOR
RETARDER.
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Install vapor retarder towards the predominately
warm, humid side
of the exterior wall.
Safing Insulation: Install at perimeter of fire
rated floor
slabs and where shown on drawings. Secure with safing
clips
spaced 24 inches o.c. maximum.
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RETAIN FOLLOWING IF EXTERIOR FINISH SYSTEM IS REQUIRED.
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EXTERIOR FINISH SYSTEM
Surfaces to receive exterior finish shall be clean
and dry prior
to application.
Joints: Apply base coat material over reinforcing
tape and trim
accessories and flush with adjacent cement board.
Force base
coat through tape to fill and level joints, or prefill
joints and
then tape and level joints. Allow to set 24 hours
before
application of base coat.
Base Coat: Apply 1/16 inch minimum thick base coat
over entire
surface. Base coat shall be uniform, smooth, and
flat. Allow to
set 24 hours before application of exterior finish.
Textured Coating: Provide 1/16 inch minimum, 3/16
inch maximum
coating thickness in specified texture.
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SPECIFY REQUIRED TEXTURE BELOW.
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Lace Finish: Trowel on a first coat. Before surface
moisture
leaves, skip-trowel on second coat with trowel held
flat.
Spanish Finish: Trowel on a smooth first coat.
Apply a second
coat using random, overlapping trowel strokes.
Sandstone Finish: Trowel on a first coat and immediately
double
back with a second coat. Using a sponge float, press
surface to
achieve required texture.
Float Finish: Trowel on finish and immediately double
back with
a second coat. Rub surface with a wood float using
a uniform,
circular motion to bring sand particles up to the
surface.
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RETAIN FOLLOWING IF TILE OR THIN BRICK VENEER IS
REQUIRED.
CHANGE "TILE" TO "THIN BRICK"
BELOW AS REQUIRED.
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TILE OR THIN BRICK VENEER
Comply with applicable requirements of Division 4
Section "Unit
Masonry".
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RETAIN ABOVE FOR THIN BRICK OR BELOW FOR TILE. IF
RELATED
SECTION IS NOT INCLUDED IN PROJECT MANUAL, IT MAY
BE NECESSARY TO
EXPAND THIS SECTION TO SPECIFY ADDITIONAL REQUIREMENTS.
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Comply with applicable requirements of Division 9
Section "Tile".
Skim Coat: Apply uniform 1/8 inch minimum thick
coat of mortar
over cement board. Surface shall be smooth and flat.
Allow to
set 24 hours before application of tile or thin brick.
Installation: Comply with ANSI A108.5 requirements
for thin-set
installation. Use notched trowel of size required
by thickness
of tile or thin brick. Apply uniform setting bed
to skim coated
surface. Back-butter tile or thin brick and firmly
press into
freshly applied mortar; use sliding and twisting
motion to embed
units and obtain complete mortar contact. Allow
mortar to set
for 24 hours before application of grout.
Grout: Comply with ANSI A108.10 and TCA Handbook
for Ceramic
Tile Installation. Force maximum amount of grout
into joints and
tool grout into joints to provide neat and uniform
appearance.
Clean grout from finished surfaces. Cure grout as
required.
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RETAIN FOLLOWING IF AGGREGATE COATING IS REQUIRED.
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AGGREGATE COATING
Apply to taped exterior cement board surface as specified
in
Division 9 Section "Aggregate Coatings".
SEALANTS
Apply sealants around perimeter of and penetrations
through
cement board building panel systems as specified
in Division 7
Section "Joint Sealers".
END OF SECTION 07480
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Copyright 1991 by U.S. Gypsum Co.
A limited license is extended to qualified design
professionals
to duplicate and print this guide specification for
the purpose
of incorporating products manufactured by U.S. Gypsum
Co. into a
construction specification or purchase order.
Notice: We shall not be liable for incidental and
consequential
damages, directly or indirectly sustained, nor for
any loss
caused by application of these goods not in accordance
with
current printed instructions or for other than the
intended use.
Our liability is expressly limited to replacement
of defective
goods. Any claim shall be deemed waived unless made
in writing to
us within thirty (30) days from date it was or reasonably
should
have been discovered.
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