Technical Specifications
DEILIVERY AND STORAGE OF MATERIALS
ENVIRONMENTAL CONDITIONS
INTERIOR APPLICATIONS
EXTERIOR APPLICATIONS
PANEL MICROCRACKING
INSTALLATION
All materials should be delivered and stored in their original unopened package and stored in an
enclosed shelter providing protection from damage and exposure to the elements. Even though the
stability and durability of USG Durock® Brand Cement Board with EdgeGuard is unaected by the
elements, moisture and temperature variations may have an eect on the bonding eectiveness of
basecoats and adhesives. Store all USG Durock® Brand Cement Board with EdgeGuard panels flat.
In cold weather and during USG Durock® Brand Cement Board with EdgeGuard panel and tile
installation, temperatures within the building shall be maintained within the range of 40 to 100°F
(5 to 38°C). Adequate ventilation shall be provided to carry o excess moisture.
The building shall be enclosed and the HVAC system operating so that wood framing shall reach
the moisture content it will reach in service. Do not install board when the board is wet.
In exterior applications, USG Durock® Brand Cement Board with EdgeGuard should not be left
uncovered for a period of time exceeding 90 days. Discoloration or staining may occur due to
exposure to the elements which will not aect performance of the panel. Finishes, leveling/skim
coats and basecoats should not be applied to USG Durock® Brand Cement Board with EdgeGuard
panel that is wet or frozen or that contains frost. After application, and for at least 24 hours,
finishes, leveling/skim coats and basecoats should be eectively protected from rain and excessive
moisture. In cold weather and during finish applications, USG Durock® Brand Cement Board with
EdgeGuard panel, skim or basecoat, mortar, finish material and air temperature must be at least
40°F (5°C) and must remain at this temperature or higher for at least 24 hours after application.
Hot and dry weather may aect working time of leveling/skim or basecoat and finish materials.
Under rapid drying conditions, dampening or light fogging of board, leveling/skim or basecoat
surface may be required to improve workability.
USG Durock® Brand Cement Board with EdgeGuard is formulated to develop fine microcracking (also
called multiple cracking) in the panel. The microcracking process helps to evenly relieve the stored
strain energy in the product due to handling and installation, external loads and/or panel restrained
movement. The presence of microcracks in the panel should not be considered a product defect.
A. Install cement board with ends and edges closely abutted, but not forced together. Stagger
end joints in successive courses.
B. For flooring applications over a wood-based substrate, laminate USG Durock® Brand Cement
Board with EdgeGuard to subfloor using Type 1 organic adhesive or latex-modified thin-set
mortar suitable for bonding cement board. Fasten to subfloor with 1-1/4 in. (32 mm) USG
Durock™ Brand Tile Backer Screws for wood framing (or equivalent) or 1-1/2 in. (38 mm) hot-
dipped galvanized roofing nails spaced 8 in. (203 mm) o.c. in both directions with perimeter
fasteners at least 3/8 in. (10 mm) and less than 5/8 in. (16 mm) from ends and edges. Drive
nails and screws so that bottoms of heads are flush with panel surface to ensure firm panel
contact with subfloor. Do not overdrive fasteners. Prefill joints with tile-setting mortar or
adhesive and then immediately embed USG Durock™ Brand Tile Backer Tape and level joints.
C. For wall application, fasten USG Durock® Brand Cement Board with EdgeGuard panels to
framing with specified fasteners. Drive fasteners into field of panels first, working toward ends
and edges. Hold panels in firm contact with framing while driving fasteners. Space fasteners
maximum 8 in. (203 mm) o.c. for walls, 6 in. (152 mm) o.c. for ceilings, with perimeter fasteners
at least 3/8 in. (10 mm) and less than 5/8 in. (16 mm) from ends and edges. Drive nails and
screws so bottoms of heads are flush with panel surface to ensure firm panel contact with
framing. Do not overdrive fasteners. Approved fasteners include: USG Durock™ Brand Tile
Backer Screws for steel framing (or equivalent), 1-1/4 in. (32 mm) and 1-5/8 in. (41 mm) for
14- to 20-gauge steel framing; USG Durock™ Brand Tile Backer Screws for wood framing (or
equivalent), 1-1/4 in. (32 mm), 1-5/8 in. (41 mm) and 2-1/4 in. (57 mm) for wood framing. Nails
(1-1/2 in. [38 mm] hot-dipped galvanized roofing nails). Prefill joints with tile-setting mortar or
adhesive and then immediately embed USG Durock™ Brand Tile Backer Tape and level joints.