Technical Specifications
D. Cement board should be cut to size with a knife and straight edge. A power saw should be
used only if it is equipped with a dust-collection device. Installer should wear NIOSH/MSHA-
approved dust mask.
E. If waterproofing is desired, use USG Durock™ Brand Waterproofing Membrane or USG Durock™
Brand Liquid Waterproofing Membrane. See USG Durock™ Brand Waterproofing Membrane
submittal sheet (CB595) or USG Durock™ Brand Liquid Waterproofing Membrane submittal sheet
(CB817) for product information.
Refer to USG Durock® Brand Cement Board System Guide (SA932EG) for complete installation
information, including good design practices. For technical assistance, call USG Technical Service
at 800 USG.4YOU (874-4968).
1. Designed for positive or negative uniform loads up to 60 psf. For complete information on
the use of USG Durock® Brand panels in exterior systems, consult uniform load table on
Page 4 for applicable positive or negative uniform loads on wall systems.
2. Wall applications: Maximum stud spacing: 16 in. (406 mm) o.c. (24 in. [610 mm] o.c. for cavity
shaft wall assembly). Framing shall be designed (based on stud properties alone) not to
exceed L/360 deflection for tile and thin brick, L/240 for direct-applied exterior finish systems.
Maximum fastener spacing: 8 in. (203 mm) o.c. for wood and steel framing; 6 in. (152 mm) o.c.
for ceiling applications.
3. Floor applications: Maximum joist spacing 24 in. (610 mm) o.c. The subfloor system should be
designed with a minimum deflection limit of L/360 for the span. Some finish materials may
require a more rigid subassembly (such as large format tile and natural stone products). In
these cases, follow the manufacturer’s minimum requirements. The subfloor should be APA
Span-Rated Plywood or OSB with an Exposure 1 classification or better with tongue and groove
or back blocked at the unsupported edges.
4. 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.
5. Brittle coatings, such as epoxy coatings, are not recommended for use with USG Durock®
Brand Cement Board with EdgeGuard. USG Durock® Brand Cement Board with EdgeGuard
is intended for use with tile, thin brick and exterior stucco coatings only.
6. Maximum dead load for ceiling system is 7.5 psf.
7. Steel framing must be 20-gauge or heavier.
8. Do not use drywall screws or drywall nails. Do not use drywall joint tape.
9. Do not use 1/4 in. (6.4 mm) USG Durock® Brand Cement Board with EdgeGuard for wall or
ceiling applications. 1/4 in. (6.4 mm) USG Durock® Cement Board with EdgeGuard is for use in
interior applications only.
10. Do not use USG Durock® Brand Cement Board with EdgeGuard with vinyl flooring.
11. USG Durock® Brand Cement Board with EdgeGuard is not designed for use as a structural panel.
12. Maximum installed weight of the finish system should not exceed 15 psf.
13. USG Durock® Brand Cement Board with EdgeGuard panels should not be used in areas where
they are exposed to temperatures that exceed 200°F (93°C).
14. In locations close to salt water or other challenging environments, design professionals
should consider the use of stainless steel fasteners.
15. Do not use lightweight setting-type joint compounds or ready-mix joint compounds directly
over USG Durock® Brand Cement Board with EdgeGuard.
INSTALLATION CONT.
LIMITATIONS