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SA932 09305

DUROCK® Brand

systemscement board

DUROCK� Brand DUROCK® Brand Cement Board offers architects, builders and tile contractors a strong, water-durable tile base for Cement Board tub and shower areas. Also an ideal underlayment for tile on floors and countertops in new construction and

remodeling. Board is readily applied over wood or steel framing spaced 16� o.c. with corrosion-resistant wood orsteel screws or hot-dipped galvanized roofing nails. After joints are treated, ceramic wall or floor tile is appliedusing latex fortified mortar or Type I organic adhesive.

DUROCK Brand Cement Board is preferred by many applicators as a base for finishes used in building exteriors.See publication SA700 for complete information on the applications of this product. The 1/2� thick DUROCK BrandCement Boards are Listed by Underwriters Laboratories Inc. for use with UL-Listed solid-fuel room heaters and fire-place stoves. Used as a wall shield, board reduces by two thirds the manufacturer-specified clearance (minimum12�) between room heater or stove and combustible wall surface. Board may also be used as a floor protector inplace of one layer of 3/8� thick millboard. For hearth extensions, see Specification 3.6B.

DUROCK® Brand In addition to standard 1/2� DUROCK Brand Cement Board, DUROCK® Brand Underlayment is available for floors and Underlayment countertops. Its nominal 5/16� thickness helps eliminate transition trim when abutting carpet or wood flooring, and

helps minimize level variations with other finish materials. Its 4� x 4� size is easy to handle and helps cut down onwaste. Applies directly over old substrate on countertops to save time.

DUROCK™ Brand Corrosion-resistant; 8-gauge; wafer heads with countersinking ribs to prevent stripout; self-drilling points. DUROCK

Screws Brand Wood Screws come in three lengths: 1-1/4�, 1-5/8� and 2-1/4�. DUROCK Brand Steel Screws can be usedwith steel framing where steel thickness is from 14 to 20-gauge; they come in two lengths: 1-1/4� and 1-5/8�.Both wood and steel screws have heads a minimum of 0.40� in diameter; their driving recess is a No. 2 “Phillips”design.

DUROCK™ Brand Akali-resistant glass-fiber tape reinforces joints to provide a strong, continuous surface. Each roll 2� x 50�,Joint Tape 2� x 250�or 4� x 150�.

Features and High Strength – High flexural strength resists bending to prevent finish cracking.Benefits of – High compressive strength to resist impact damage.DUROCK® BrandCement Board

Dual Surface – Smooth side for mastic applications; increases adhesive coverage.– Textured surface enhances bonding, reduces tile slip with mortar applications.

Dimensional – Low thermal and hygrometric expansion helps prevent cracking.Stability – Will not swell, soften, decay, delaminate, or disintegrate in water.

Fire-Resistance – Noncombustible panel.– Assemblies with 1/2� DUROCK Brand Cement Board have achieved 1 and 2 hr. fire-resistance ratings.

Light Weight – At approximately 3 psf, the 1/2� thick board is one fourth the weight of a conventional 1� thick metal lath and portland cement plaster system.

Easy Installation – Easy to cut and fasten.– Dry panel application eliminates cement mixing and drying time, shortening job schedules and lowering

in-place cost.

Convenient sizes – May be ordered in sizes to meet job requirements (see table of sizes and packaging).

Versatility – Provides a smooth, sound base for glass and ceramic mosaics; ceramic and quarry tile; lugged tile; thin stone tile; and thin brick.

– Adaptable for fences, fireplace fronts, mobile home skirting, agricultural buildings, UL-listed wall shield/floorprotectors, garage wainscoting and exterior finishes.

DUROCK® BrandCement Board Systems


United States Gypsum Company SA932 3

Limitations 1 Do not use drywall screws or drywall nails.2 Systems using DUROCK Brand Cement Board are designed for positive or negative uniform loads up to 50 psf.

(See publication SA700 for complete information on wind load capacity.)3 Maximum stud spacing: 16� o.c. (24� o.c. for cavity shaft wall assembly); maximum allowable deflection, based on

stud properties only, L/360. Maximum fastener spacing: 8� o.c. for wood and steel framing on floors and walls; 6� o.c. for ceiling applications.

4 Maximum dead load for ceiling system is 7.5 psf.5 Steel framing must be 20 gauge or heavier.6 Not recommended for vinyl flooring.7 5/16� thickness should not be used for walls or ceilings.

Product Data Material Formed in a continuous process of aggregated portland cement slurry with polymer-coated, glass-fiber mesh completely encompassing edges and back and front surfaces.Edges Formed smooth—Patent No. 4,916,004.Ends Square cut.

Sizes and Packaging Type Size (Thickness xWidth x Length)(1) Units (pcs)(2)

Cement Board 1/2� x 32� x 5� 50

1/2� x 36� x 5� 50

1/2� x 32� x 8� 30

1/2� x 36� x 8� 30

1/2� x 48� x 8� 30

5/8� x 36� x 5� 30

5/8� x 32� x 8� 30

5/8� x 48� x 8� 24

Underlayment 5/16� x 48� x 4� 40

5/16� x 36� x 5� 40

(1) Other lengths available. Contact your USG Representative. (2) Stretch-wrapped and shipped in packaging units as shown.

Typical Physical Properties ASTM test Cement UnderlaymentProperty reference board value (1/2�) value (5/16�)Flexural strength-psi C947-81 750 1250

Indentation strength—psi 1� dia. disc @ 0.02� indent. D2394 2300 2300

Uniform load—psf studs 12� o.c. — 50 max. —

Water absorption-% by wt. 24 hrs. C473-84 10 10

Nail pull resistance—lb. 0.4� head diameter (wet or dry) C473-84 125 —

Weight—psf C473-84 3 2

Freeze/thaw resistance—Procedure B number of cycles C666-84 100 100

with no deterioration

Surface burning characteristics—flame/smoke E84 5/0 5/0

Thermal �R�/k value C177 0.26/1.92 —

Standard method for evaluating ceramic floor tile C627 Residential Residential

installation systems

Min. bending radius1—ft. — 8 —

(1) Requires special framing. Details available on request.

Building Refer to current National Evaluation Service Report Nos. 259 and 396 for allowable values and/or conditions of Code Data use concerning material presented in this document.

Standards DUROCK Brand Cement Board exceeds the ANSI Standards for cementitious backer units (CBU). See ANSI A118.9-1992 for Test Methods and Specifications for CBU and ANSI 108.11-1992 for Interior Installation of CBU. AllDUROCK Brand Cement Board products meet ASTM Standard E136 for noncombustibility.

LU®

Listed 34L2For floor protectors and wall shields

09305/UNIBuyLine 3900

1 hour Partitions

Detail/Physical Data Description Fire STC Sound SystemTest Test Reference

Wood-Framed/ 1/2� DUROCK Brand cement panel and 1/4� ceramic tile— UL Des 37 USG-840404 A

Load Bearing 2 x 4 studs 16�o.c.—3-1/2� THERMAFIBER SAFB—panel U329 40 Based on attached with 1-5/8� DUROCK screws or 1-1/2� hot-dipped alternative designgalvanized nails—alternative design 5/8� SHEETROCK Brand —USG-840314gypsum panels, FIRECODE core, one side

1/2� DUROCK Brand cement panel—base layer 15/32� UL Des N/A Bplywood or oriented strand board—2 x 4 studs 16� o.c.— U3033� THERMAFIBER SAFB—panel attached with 1-5/8� DUROCK

screws or 1-1/2� hot-dipped galvanized nails—5/8�

SHEETROCK Brand gypsum panels, FIRECODE core, other side

Steel Framed/ 1/2� DUROCK Brand cement panel—base layer 5/8� UL Des N/A C

Load Bearing1 SHEETROCK Brand gypsum panels or sheathing, FIRECODE U473core—3-1/2� studs 16� o.c.—3� THERMAFIBER SAFB

5/8� SHEETROCK Brand gypsum panels, FIRECODE core, UL Des N/A Dattached with 1-5/8� screws—base layer 1/2� DUROCK U485Brand cement panel—panel attached with 1-1/4� DUROCK

Brand screws —3-1/2� studs 16� o.c.—3� THERMAFIBER

SAFB

1/2� DUROCK cement panel—3-1/2� studs 16� o.c.— UL Des N/A E3� THERMAFIBER SAFB—panel attached with U4041-1/4� DUROCK screws—5/8� SHEETROCK brand gypsum panels, FIRECODE core, other side

Steel Framed/ 1/2� DUROCK Brand cement panel and 1/4� ceramic tile— UL Des 482 SA-840321 G

Non-Load Bearing1 2-1/2� studs 16� o.c.—2-1/2� THERMAFIBER SAFB—panel U442 502 Based on attached with 1-1/4� DUROCK Brand screws—alternative alernative designdesign 5/8� SHEETROCK Brand gypsum panels, FIRECODE —SA-840313core, one side

Plumbing Chase Wall—1/2� DUROCK Brand cement panel and UL Des 61 Based on 3� SAFB H1/4� ceramic tile—1-5/8� studs 16� o.c. in two rows with U445 & 3-5/8� studshorizontal braces—1-1/2� THERMAFIBER SAFB in both stud —SA-840524cavities—panel attached with 1-1/4� DUROCK Brand screws 60 Based on 3� SAFB —alternative design 5/8� SHEETROCK Brand gypsum panels, & alternative designFIRECODE core, one side —SA-840515

1/2� DUROCK Brand cement panel and maximum 1/2� UL Des 472 Based on 5/8� Ipolystyrene insulation board one side—3-5/8� studs U457 SHEETROCK Brand 16� o.c.—3� THERMAFIBER SAFB—panel attached with gypsum panels,1-1/4� DUROCK Brand screws—5/8� SHEETROCK Brand FIRECODE core—gypsum panels, FIRECODE C core,other side USG-840222

Plumbing Chase Wall—1/2� DUROCK Durock cement panel UL Des 57 Based on 3-5/8� Jone side—1-5/8� studs 16� o.c. in two rows with horizontal U458 studs and 3� SAFBbraces—1-1/2� THERMAFIBER SAFB in both stud cavities— —SA-840505panel attached with 1-1/4� DUROCK Brand screws—5/8�

SHEETROCK Brand gypsum panels, FIRECODE C core, other side



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Detail/Physical Data Description Fire STC Sound SystemTest Test Reference

Wood-Framed/ Plumbing Chase Wall—1/2� DUROCK Brand cement panel WHI-495-0505 50 SA-840523 K

Load Bearing and 1/4� ceramic tile—2 rows 2 x 4 studs 16� o.c. on 2 x 8 and 0508 common plate—3-1/2� THERMAFIBER SAFB in both stud load bearing upcavities—panel attached with 1-5/8� DUROCK Brand screws to 50% allowableor 1-1/2� hot-dipped galv. nails 8� o.c. design load

1/2� DUROCK Brand cement panel—base layer 5/8� UL Des U308 N/A LSHEETROCK Brand gypsum sheathing, FIRECODE core—2 x 4 studs 16� o.c.—3� THERMAFIBER SAFB—panels attached with 2-1/4� DUROCK Brand screws or hot-dipped galvanized nails—double-layer 5/8� SHEETROCK Brand gypsum panels,FIRECODE core, other side

Steel-Framed/ 1/2� DUROCK Brand cement panel—base layer 1/2� UL Des U474 N/A M

Non-Load Bearing1 SHEETROCK Brand gypsum panels, FIRECODE C core, both sides —3-5/8� studs 16� o.c.—3� THERMAFIBER SAFB—cement panel attached with 1-5/8� DUROCK Brand screws— alternativedesign double layer 1/2� SHEETROCK Brand gypsum panels, FIRECODE C core, on one side

1/2� DUROCK Brand cement panel and 1/4� ceramic tile— UL Des U443 582 SA-851028 Nbase layer 1/2� SHEETROCK Brand gypsum panels, FIRECODE 562 Based on C core—3-5/8� studs 16� o.c.—3� THERMAFIBER SAFB— alternativecement panel attached with 1-5/8� DUROCK Brand screws— design—alternative design double-layer 1/2� SHEETROCK Brand SA-851016gypsum panels, FIRECODE C core, one side

Plumbing Chase Wall—1/2� DUROCK Brand cement panel and UL Des U444 65 SA-851112 O1/4� ceramic tile—base layer 1/2� SHEETROCK Brand gypsum 62 Based on panels, FIRECODE C core—1-5/8� studs 16� o.c. in two rows alternative with horizontal braces—1-1/2� THERMAFIBER SAFB in both design—stud cavities—cement panel attached with 1-5/8� DUROCK SA-851102Brand screws—alternative design double-layer 1/2�

SHEETROCK Brand gypsum panels, FIRECODE C core, one side

Cavity Shaft Wall—1/2� DUROCK Brand cement panel— UL Des 415 or N/A P5/8� SHEETROCK Brand gypsum panels, FIRECODE core— U4591� SHEETROCK Brand gypsum liner panels set between C-H studs 24� o.c.—1-1/2� THERMAFIBER SAFB—cement board screw attached with 1-5/8� DUROCK Brand screws and laminated to gypsum panel with 4� strip ceramic tile mastic applied with 1/4� notched trowel midway between studs

Steel-Framed/ 1/2� DUROCK Brand cement panel—base layer 5/8� UL Des U404 N/A Q

Load Bearing1 SHEETROCK Brand gypsum sheathing, FIRECODE core—3-1/2� studs 16� o.c.—3� THERMAFIBER SAFB—panel screw attached to studs—double-layer 5/8� SHEETROCK Brand gypsum panels, FIRECODE core, other side—alternate designdouble-layer 1/2� DUROCK Brand cement panel one side

Notes: DUROCK Brand Cement Board, 5/8� thick, may be substituted for 1/2� cement board panels in all assemblies listed above. FIBEROCK® Brand Abuse-Resistant Gypsum Fiber Panels, 5/8� thick, may be substituted for 1/2� SHEETROCK Gypsum Panels, FIRECODE C core, or 5/8� SHEETROCK Gypsum Panels, FIRECODE core, in all assemblies listed above. Where thermal insulationis shown in assembly drawing, the specifiic product is required in the assembly to achieve the stated fiire rating. Fiberglass insution cannot be substituted for THERMAFIBER Insulation.Where the wall is exposed to moisture, use a moisture-resistant barrier behind the cement board.

1 Steel framing must be 20 gauge or heavier.

2 Estimate based on 25 gauge steel studs.




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DUROCK® Brand Cement Board Systems


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3⁄4" min. plywood DUROCK Brand cementboard or underlayment

DUROCK Brand interior tape

liquid or sheet membraneType I organic adhesive or latex-fortified mortar

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wood or steel joists

carpet

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3⁄4" min. plywood or OSB subfloor

Note: For bonding cement backer board to plywood subfloor, use Type 1 organic adhesive orlatex-fortified mortar that is suitable for this kind of application. For application of various types oftiles to cement backer board on floors or countertops, contact the tile manufacturer for the appropriate type of tile-setting mortar.

tile

DUROCK Brand cement board or underlayment Type I organic adhesive or

latex-fortified mortar

Counter tops Floors, interior-wood or steel joists

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hanger

20 ga. min. metal furring channel

DUROCK Brandfastener 6" o.c.

control jointDUROCK Brand cement panel ceramic tile

wire tie

20 ga. min. metal furring channel

hangerwire tie

11/2" channel

23/4"

DUROCK Brand screw 6" o.c.

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1/2" DUROCK Brand cement panel

2"x4" wood stud 16" o.c.

ceramic tile

1/2" SHEETROCK

Brand gypsum panel

DUROCK Brand wood screws 6" o.c.

Type I organic adhesive or latex-fortified mortar



DUROCK Brand cement panel must be primed before application of joint compound or use it on one side only and set the tile side with mastic.

see note above*

*

Wood soffit framingSuspended ceiling detail

Tub and shower - single layer board

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tile

wood or metal studs

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1' to 13⁄4" reinforced mortar bed

shower pan or membrane

sloped fill weep holes

crushed tile or stone

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caulk

tub rim

leveling guide


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horizontal supportat DUROCK Brand panel edge

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DUROCK Brand steel or wood screw 8" o.c.

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setting material

wood or steel studs 16" o.c. max.

membrane (if required)

Walls, interior, and exterior - wood or steel studs



DUROCK Brand tape

4" DUROCK Brand tape embedded in exterior basecoat

water barrier

DUROCK Brand screws at 8" o.c.

exterior finish

in tile areas treat DUROCK Brand joints by embedding 2" DUROCK Brand tape in tile setting material

wood or metalstuds at 16" o.c.

DUROCK Brand panel

2" DUROCK Brand tape


exteriorbasecoat

DUROCK Brand panel

tile settingmortar tile base

pool

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2 x 4 woodstuds 16" o.c.

wood plate

tub


ceramic tile

1/4" space

DUROCK Brandtape

1/2" DUROCK Brand cement panel 32" x 5'-0"

1/2" DUROCK Brand cement panel 32" x 5'-0"

DUROCK Brand screws 8" o.c.

DUROCK Brand tape

1/2" SHEETROCK Brand gypsum panel

support framing for attachment of fixtures

Use SHEETROCK Brand joint treatment system and sealer for finishing DUROCK to gypsum board joints (Refer to 3.7B) in painted areas

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treat DUROCK Brand board joints by embedding DUROCK Brand tape in tile setting material

1/2" SHEETROCK

Brand gypsum panel


Typical bathtub installation

Typical swimming pool installation (tile or exterior finish) DUROCK Brand alkali-resistant tape

DUROCK Brand wood screws

DUROCK Brand steel screws

/8" TYPE S-12an head screw

teel runner

steel framingmember–gauge and size as required

3/8" TYPE S-12pan head screw

steel framingmembers–misc.gauge and depth

Fixture attachment - steel framing

Hot-dipped galvanized roofing nails


Good Design 1 System Performance Systems covered herein have been tested and evaluated for use as described. For other system applications,Practices consult your local representative.

All details, specifications, and data contained in this literature are intended as a general guide for using DUROCK Brand Cement Board Systems. These products must not be used in a design or construction of any given structure without complete and detailed evaluation by a qualified structural engineer or architect to verify suitability of a particular product for use in the structure.

Information in this publication should be used only for DUROCK Brand Cement Board Systems, as physical proper-ties of competitive products may vary. United States Gypsum Company assumes no liability for failure resulting fromthe use of alternative materials or improper application or installation of DUROCK Brand Cement Board Systems asspecified herein.

United States Gypsum Company will provide building officials and design professionals upon written request withtest certification for published fire, sound, and structural data covering systems constructed with Company productsand assembled to meet performance requirements of established test procedures specified by various agencies.

2 Expansion and Contraction Wall surfaces should be isolated with surface control joints (sometimes referred to by the industry as expansion joints) or other means where: (a) a wall abuts a structural element or dissimilar wall or ceiling; (b) constructionchanges within the plane of the wall; (c) tile and thin brick surfaces exceed 16�. Surface control joint width shouldcomply with architectural practices.

Location of building control joints is the responsibility of the design professional/architect. Steel framing atbuilding control joints that extend through the wall (with top and bottom runner tracks broken) should have 1-1/2�cold-rolled channel alignment stabilizers spaced a maximum of 5�0� o.c. vertically. Channels should be placedthrough holes in the 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.

Cement board should be separated at all surface and building control joints. Where vertical and horizontal jointsintersect, the vertical joint should be continuous and the horizontal joint should abut it. Splices, terminals, and inter-sections should be caulked with a sealant complying with architectural practices and sealant manufacturer recom-mendations. Do not apply tile or finishes over caulked sealed expansion joints. (See SA700 for additional information).

3 Water Barrier DUROCK Brand Cement Board is vapor permeable and does not deteriorate in the presence of water. For interior applications, if a vapor retarder or waterproof construction is specified, a separate barrier must be applied over or behind the DUROCK Brand Board. For exterior applications of DUROCK Brand Cement Board, see SA700Exterior Substrate Systems.

4 Swimming Pool Enclosures DUROCK Brand Cement Board Systems may be used for the walls and ceilings around indoor swimming pools.Consideration shall be given to adequate ventilation in plenums and corrosion protection of metal hangers andframing members.

5 Soffits and Ceilings DUROCK Brand Cement Board Systems finished with ceramic tile, thin brick, and textured finish may be used onproperly vented soffits and ceilings with DUROCK Brand Screws spaced 6� o.c. max. A qualified structural engineershould evaluate design including uplift bracing.

6 Steam Rooms and Saunas For steam rooms and saunas where temperatures exceed 120 °F for extended periods, use latex-fortified portlandcement mortar; do not use organic adhesive.

7 Abuse Resistant Partitions IMPERIAL� Brand Finish Plaster and DIAMOND� Interior Finish Plaster can be applied over DUROCK Brand Cement Boardto provide a high-impact resistant wall. See United States Gypsum Company publication SA920 for specifications.

8 Window and Door Openings All window and door openings must be properly flashed and caulked.

9 Smooth Side/ DUROCK Brand Cement Board has a smooth side and a rough side. Use the smooth side for mastic applicationsRough Side and the rough side for mortar applications.



10 Shadowing and Spotting When the outside temperature differs considerably from the building�s interior temperature, airborne dirt can accumulate on the colder regions of walls, causing “shadowing” or “spotting,” particularly over fasteners and framing. This is a natural phenomenon which occurs through no fault in the products.

Where temperature, humidity, and soiling conditions are expected to cause objectionable blemishes, provide a thermal separation between the interior and exterior faces.

11 Leaching and Latex leaching and efflorescence are natural phenomena which occur with the use of latex modified mortars andEfflorescence grouts through no fault in the products. To help protect against their occurrence, follow current industry

guidelines and recommendations.

12 Vapor Retarders Humidity and temperature conditions may require a vapor retarder. Its location should be determined by a qualified mechanical engineer or architect to prevent moisture condensation within the wall.

13 Corrosion Protection All architectural components, such as anodized-aluminum window frames, trims, flashings and casings, shall be protected from alkaline building materials such as cement board, portland cement basecoats, mortars and grouts.

Specifications 1.1 Specify to meet project requirements.Part 1: Scope

General1.2 All materials, unless otherwise indicated, shall be manufactured by United States Gypsum Company and shallQualifications be installed in accordance with its current printed directions.

1.3 All materials shall be delivered in their original unopened packages and stored in an enclosed shelter providing Delivery and protection from damage and exposure to the elements. Damaged or deteriorated materials shall be removed Storage of Materials

from the premises. WARNING: Store all DUROCK Brand Cement Board panels flat. Panels are heavy and can fall over,causing serious injury or death. Do not move unless authorized.

1.4 In cold weather and during DUROCK Brand Cement Panel and tile installation, temperatures within the building shall Environmental Conditions be maintained within the range of 40 to 100 °F. Adequate ventilation shall be provided to carry off excess moisture.

Interior Applications Wood framing shall approximate the moisture content it will reach in service by allowing the enclosed building to stand as long as possible prior to the application of the cement board. Do not install board when the board is wet.Exterior Applications Finishes, leveling/skim coats and basecoats shall not be applied to DUROCK Brand Cement Panelthat is wet or frozen or that contains frost. After application, and for at least 24 hours, finishes, leveling/skim coatsand basecoats shall be effectively protected from rain and excessive moisture.

In cold weather and during finish applications, DUROCK Brand Cement Panel, skim or basecoat, mortar, finishmaterial and air temperature must be at least 40 °F, and must remain at this temperature or higher for at least 24hours after application. Hot and dry weather may affect working time of leveling/skim or basecoat and finish mate-rials. Under rapid drying conditions, dampening or light fogging of board, leveling/skim or basecoat surface maybe required to improve workability.

1.5 Steel or wood wall framing to receive DUROCK Brand Cement Panels shall be structurally sound, free from bow, andFraming in general compliance with local building code requirements. Damaged and excessively bowed studs shall be

replaced before installation of DUROCK Brand Cement Panels. Framing shall be designed (based on stud propertiesalone) not to exceed L/360 deflection for tile and thin brick, L/240 for Direct-Applied Exterior Finish Systems. Steelframing must be 20 gauge or heavier with corrosion-resistant metal coating equivalent to G60 hot-dipped galva-nized. Exterior steel framing should be laterally braced.

1.6 DUROCK Brand Panel should be cut to size with carbide-tipped knife and straight edge. Power saw should be used Installation Practices only if equipped with a dust-collection device and a NIOSH/MSHA-approved respirator is worn.

Contractors installing tile and tile-setting materials should always follow current ANSI specifications and TCAguidelines.




Part 2: 2.1 A Cement BoardProducts Materials —DUROCK Brand Cement Board, 1/2� or 5/8� thickness, 32�, 36�, or 48� width x lengths of 4� to 10�; exceeds

ANSI A118.9-1992 for cementitious backer units.—DUROCK Brand Underlayment, 5/16� thickness, 48� width x 4� length, other sizes available.

B Joint Reinforcement—DUROCK Brand Joint Tape (alkali-resistant), 2� x 50�, 2” x 250’, or 4” x 150’.C Fasteners

—DUROCK Brand Steel Screws (No. 8), 1-1/4� and 1-5/8� for 14 to 20 gauge steel framing; DUROCK Brand WoodScrews (No. 8), 1-1/4�, 1-5/8�, and 2-1/4� for wood framing.

—Nails (1-1/2� hot-dipped galvanized roofing nails).D Subfloor—(5/8�) (3/4�) plywood or oriented strand board (OSB), 4� x 8� sheets, exterior grade or better, exterior

glue conforming with PS-1-66, T&G or back block long edges.E Adhesives/Mortars

Products compatible with alkaline or portland cement-based DUROCK Brand Cement Board:—Meeting ASTM C557-73: multipurpose adhesive (for subfloor to framing attachment).—Meeting ANSI A136.1 Type I.—Meeting ANSI A118.1: dry-set mortar mixed with acrylic latex additive.—Meeting ANSI A118.4: latex portland cement mortar.

F GroutProducts compatible with high pH-based DUROCK Brand Cement Board:—Meeting ANSI A118.6: specify type.

G Tile—Tile shall meet ANSI A137.1.H Membrane—#15-lb. felt or 4-mil polyethylene membrane, if required, in accordance with local building codes.

Part 3: 3.1 A Subfloor—Apply 3/8� bead of multipurpose adhesive to center of top flange of joists. Place 5/8� min. exterior Execution Floors grade plywood or OSB sheets with long dimension across or parallel to wood or steel joists spaced max. 16� o.c.

Fasten plywood to steel joists with 1-15/16� pilot point self-drilling screws spaced 16� o.c. Fasten plywood to wood joists with adhesive and suitable nails or screws spaced max. 12� o.c.

B Panel Application—Laminate 5/16� DUROCK Brand Underlayment to subfloor using Type 1 organic adhesive, latex- fortified mortar or dry-set mortar mixed with acrylic latex additive that is suitable for bonding cement backer boardto plywood subfloor, with 1/4� square-notched trowel for mortar, 5/32� V-notched trowel for adhesive. Place under-layment with joints staggered from subfloor joints. Fit ends and edges closely but not forced together, leaving a 1/8�gap. Fasten to subfloor with 1-1/4� DUROCK Brand Wood Screws or 1-1/2� hot-dipped galvanized roofing nailsspaced 8� o.c. in both directions with perimeter fasteners at least 3/8� and less than 5/8� from ends and edges.

1/2� and 5/8� DUROCK Brand Cement Board—Same procedure as DUROCK Brand Underlayment.

3.2 A Framing—Space wood and steel framing a maximum of 16� o.c. (24� o.c. for UL Design U459 or U415). The studs of Walls freestanding furred walls must be secured to the exterior wall with wall furring brackets or laterally braced with horizontal

studs or runners spaced 4� o.c. max. Laterally brace all steel-framed walls prior to the application of joint treatment.B Panel Application—After tub, shower pan or receptor is installed, place temporary 1/4� spacer strips around

lip of fixture. Pre-cut board to required sizes and make necessary cut-outs. Fit ends and edges closely but not forced together, leaving a 1/8� gap. Install board abutting top of spacer strip. Stagger end joints in successivecourses. Fasten boards to wood studs spaced max. 16� o.c. and bottom plates with 1-1/4� DUROCK Brand WoodScrews or 1-1/2� hot-dipped galvanized roofing nails spaced 8� o.c. Fasten DUROCK Brand Cement Board to steelstuds spaced max. 16� o.c. and bottom runners with 1-1/4� DUROCK Brand Steel Screws spaced 8� o.c. withperimeter fasteners at least 3/8� and less than 5/8� from ends and edges. In double-layer walls where cementboards are installed over base-layer gypsum boards, apply a vapor-permeable water barrier over gypsum boards.

C Shaft Wall—Attach DUROCK Brand Cement Board over base layer of gypsum panels with 1-5/8� DUROCK Brand Steel Screws at 8� o.c. to studs. Since studs are at 24� o.c., laminate cement board to base layer of gypsum panelswith a 4� wide strip of construction adhesive between studs. Apply adhesive with a 1/4� square-notched trowel.

D Exterior Walls—Attach DUROCK Brand Cement Board with corrosion-resistant screws spaced a maximum of 8� o.c. over framing spaced a maximum of 16� o.c. Apply a weather resistive barrier and flashing behind thepanels as required. Follow the exterior finish manufacturer’s recommendations for application over DUROCK

Brand Cement Board.



3.3 A Base—Install minimum 3/4� exterior-grade plywood base across wood cabinet supports spaced maximum Countertops 16� o.c. Position ends and edges over supports.

B Membrane—Staple-attach 15-lb. felt or 4-mil polyethylene film using 1/4� galvanized stapes over plywood base.C Panel Application—Secure 5/16� DUROCK Brand Underlayment to plywood. Fasten to plywood with 1-1/4� DUROCK

Brand Wood Screws or 1-1/2� hot-dipped galvanized roofing nails spaced 8� in both directions and around edges;fit ends and edges closely but not forced together, leaving a 1/8� gap.

Application of 1/2� or 5/8� DUROCK Brand Cement Board—Use same procedure as for DUROCK BrandUnderlayment.

D Joint Finishing—Prefill joints with latex-fortified mortar or Type 1 organic adhesive; completely embed DUROCK

BRAND Interior Tape; and level all joints and outside corners.

3.4 A Framing—Ceiling joists, furring channels or strips must be spaced max. 16� o.c. Framing must be capable ofCeilings supporting the total ceiling system dead load, including insulation, ceramic tile, bonding materials and cement

board, with deflection not exceeding L/360 of the span. When steel framing is used, min. 20 ga. is required.B Panel Application—Apply 1/2� DUROCK Brand Cement Board to framing with long dimension across framing. Center

end or edge joints on framing and stagger joints in adjacent rows. Fit ends and edges closely, but not forcedtogether, leaving a 1/8� gap. Fasten boards to steel framing with 1-1/4� DUROCK Brand Steel Screws spaced 6� o.c.and to wood framing with 1-5/8� DUROCK Brand Wood Screws spaced 6� o.c. with perimeter fasteners at least 3/8�and less than 5/8� from ends and edges. If necessary, provide additional blocking to permit proper attachment.Edges or ends parallel to framing shall be continuously supported.

3.5 A Furring—Cut 1/2� DUROCK Brand Cement Board to panel and furring strip sizes with a scoring tool or circular saw Wall Shield with a carbide-tipped blade. Attach a double layer of furring strips to wall framing with 2-1/4� DUROCK Brand Wood

Screws or 2-1/4� galvanized roofing nails with 3/4� minimum framing penetration.B Panel Application—Attach 1/2� DUROCK Brand Cement Board wall shield through furring to wall framing with 2-3/4�

galvanized roofing nails with 3/4� minimum framing penetration.

3.6 A Panel Application—Apply 1/8� to 1/4� thick latex-fortified portland cement to solid surface—never on top of Floor Protector carpeting or padding. Attach 1/2� DUROCK Brand Cement Board with 1-1/4� DUROCK Brand Wood Screws or 1-1/2�

galvanized roofing nails at 8� o.c. both directions and with 3/4� minimum flooring penetration.B Hearth Extension—To substitute DUROCK Cement Board in hearth extension designs, use the guidelines

specified by local building code and the fireplace manufacturer, and the following formula:k-value DUROCK Brand x Hearth extension = Thickness of DUROCK Brand k-value specified thickness Cement Panels (not less

(specified) than hearth extension thickness specified)

Example: If the fireplace manufacturer or code requires one layer of 3/4� millboard with a k-value of .84, use the formula as follows to determine the required layers of DUROCK Brand Cement Panels:

1.92.84

x .75� = 1.71� or four layers.

Installation of panels for hearth extension is same as 3.6.A.

3.7 A For Tile and Thin Brick—Prefill all DUROCK Brand Cement Board joints, and joints where DUROCK Brand Cement Joint Treatment Boards abut other panels or surfaces such as gypsum board, with tile-setting mortar or adhesive, and thenApplication

immediately embed tape and level the joints.B For Dry Untiled Areas—For small areas where the DUROCK Brand Cement Board will not be tiled, such as a board

extending beyond the tiled area and abutting another surface, treat joints as follows. Seal DUROCK Brand Board with DUROCK Brand or Type I Ceramic Tile Adhesive. (Mix four parts adhesive with one part water.) EmbedSHEETROCK� Brand Joint Tape over joints and treat fasteners with SHEETROCK� Brand Setting-Type Joint Compound(DURABOND� 45 or 90) applied in conventional manner. Flat trowel SHEETROCK Brand Setting-Type Joint Compound over board to cover fasteners and fill voids to a smooth surface. Finish joints with at least two coatsSHEETROCK� Brand Ready-Mixed Joint Compound. Do not apply ready-mixed or setting-type joint compound over unsealed board.




Manufactured by United States Gypsum Company125 South Franklin StreetChicago, IL 60606

© 2002, USG CorporationSA932/rev. 3-02Printed in U.S.A.

Technical Service

800 USG.4YOUWebsite

www.usg.comSamples/Literature

888 874.2450Samples/Literature E-mail

[email protected]/Literature/Fax

888 874.2348Customer Service

800 950.3839

replacement of defective goods.Any claim shall be deemed waivedunless made in writing to us withinthirty (30) days from date it was or reasonably should have been discovered.Note All products described here may not be available in all geo-graphic markets. Consult your local sales office or representativefor information.Safety First!Follow good safety and industrialhygiene practices during handlingand installing all products andsystems. Take necessary precau-tions and wear the appropriatepersonal protective equipment as needed. Read material safetydata sheets and related literature on products before specificationand/or installation.

Metric SpecificationsUSG Corporation, through itsoperating subsidiaries, will pro-vide metric conversions on itsproducts and systems to helpspecifiers match metric designsizes. In addition, some productsare available in metric dimen-sions from selected manufactur-ing plants. Refer to SA100Construction Selector for addi-tional information and a Table ofMetric Equivalents.TrademarksThe following trademarks usedherein are owned by United StatesGypsum or a related company:DUROCK, DURABOND, FIBEROCK,FIRECODE, SHEETROCK, USG,IMPERIAL, DIAMOND.THERMAFIBER isa trademark of ThermafiberLLC.NoticeWe shall not be liable for inciden-tal and consequential damages,directly or indirectly sustained, norfor any loss caused by application of these goods not in accordancewith current printed instructions or for other than the intended use.Our liability is expressly limited to

3.8 A Tile Application—Plan tile layout, then spread DUROCK Brand Ceramic Tile Adhesive with trowel recommended Interior by tile manufacturer held at 45° angle. Apply no more adhesive than can be covered in 20-30 mins. Open timeCeramic Tile will vary according to temperature and humidity. NOTE: When applying over old ceramic tile, allow adhesive toApplication

set 10-15 mins. before applying new tile. Wall tiles may be set top down or bottom up. Press, do not slide, tilesand sheets of tile into adhesive. Maintain accurate joint alignment and spacing as tiles are positioned. Use wooden or rubber-faced beating block, tapped lightly with a mallet to level and ensure solid tile positioning.Check occasionally to ensure at least 95% adhesive transfer to back of tile. Avoid adhesive squeeze-upbetween tiles. It may be necessary to butter adhesive on backs of large pavers and quarry tile. NOTE: Contractorsinstalling ceramic tile should always follow ANSI Specifications and TCA Guidelines. Do not use DUROCK or Type I Ceramic Tile Adhesive for the installation of button back tile, slate, marble and floor tiles over 6� x 6�; instead,use latex-fortified mortar.

B Recommended Adhesive and Mortar Coverage—Recommended adhesive and mortar coverage will vary basedon the substrates and notched trowel sizes commonly recommended by the tile or adhesive manufacturer.

C Drying Time—Do not walk on floors for at least 48 hrs. unless walking boards or plywood sheets are used. To finish job, wait 24 hrs. after tile has been installed for walls and countertops, 48 to 72 hrs. for floors, before

D Grouting—Select, prepare and install grout in accordance with recommendations provided by grout manufacturers.

3.9 A Follow the exterior finish manufacturer’s recommendations for finishes applied to DUROCK Brand Cement Board Exterior Applications B It is recommended that a weather resistive barrier and flashing be installed behind DUROCK Brand Cement

Board in direct-applied finish applications to provide a means for draining any intruding moisture safely from the exterior of the building.

C Follow the manufacturer’s recommendation, design professional, or contract documents for proper sealants andflashings at openings such as windows and doors.

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