Exterior Cement Board Systems (DUROCK). CSI 3-Part Specifications.

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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