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Wood Framing 1 x 4 wood furring may be used for screw application where support member spacing is 24 o.c. max. Furring of 2
nom. thickness should be used for nail application of board or where framing spacing is from 24 to 48o.c. max.
Steel Framing Installation of grillage should be the same as for single-layer application—(see USG Publication SA923 for
application information).
Ventilation Where the area above the ceiling board opens to an attic space above habitable rooms, the space should be
vented to the outside in accordance with local building codes. Where the ceiling board is applied directly to rafters
or to roof-ceiling joists (as in flat roof construction) that extend beyond habitable rooms, vents are required at each
end of each rafter or joist space. Vents should be screened and be a minimum of 2 wide x full length between
rafters (or joists). Vents should be attached through board to min. 1 x 2 backing strips installed prior to board
application. Vent openings should be framed and located within 6 of outer edge of eave.
Weather Protection At the perimeter and vertical penetrations, the exposed core of panels must be covered with SHEETROCK®No. 401/402
Metal Trim or securely fastened moldings. In areas subject to freezing temperatures and other severe weather
conditions, shingled roofs should be installed in accordance with good roofing practices. Fascia boards should extend at
least 1/4 below the ceiling board or adjacent trim moldings, whichever is lower,to provide a drip edge.
Intersections Where ceiling board expanse exceeds 4 ft., a space of at least 1/4 should be provided between edge of ceiling
board and adjacent walls, beams, columns,and fascia. This space may be screened or covered with molding,but
should not be caulked.
Control Joints SHEETROCK Brand Exterior Gypsum Ceiling Board, like other building materials,is subject to structural movement,
expansion, and contraction due to changes in temperature and humidity.
Install a S
HEETROCK
®
Zinc Control Joint No. 093 or a control joint consisting of two pieces of SHEETROCK No. 401/402
Metal Trim back-to-back in ceiling board where expansion or control joints occur in the exterior wall or roof.Where aluminum H-moldings are used, they will serve as control joints provided the board is not tightly inserted.
Joint Treatment SHEETROCK Brand DURABOND Setting-Type and EASY SAND Lightweight Setting-Type Joint Compounds are hardening-
type products developed to provide faster finishing of drywall, even under slow drying conditions. Rapid chemical
hardening and low shrinkage permit same-day finishing and usually next-day decoration. Features exceptional
bond; virtually unaffected by humidity extremes.
SHEETROCK
®
Brand Exterior
Gypsum Ceiling Board
Application Tips
SAFETY FIRST!
Follow good safety practices.
Read material safety data
sheets and related literature on
products before specification
and/or installation.
Trademarks
The following trademarks used
herein are owned by United
States Gypsum or a related
company: D
URABOND,EASY SAND,
S
HEETROCK.
Note
Products described here may
not be available in all geographic markets. Consult your
U.S. Gypsum Company sales
office or representative for information.
Notice
We shall not be liable for incidental or 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 their 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
the date it was or reasonably
should have been discovered.
Manufactured by
United States Gypsum Company
125 South Franklin Street
Chicago, IL 60606
800 USG.4YOU (874-4968)
www.usg.com
WB2354/2-04
©2004, United States Gypsum Company
Printed in U.S.A.
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