1、 Printed in U.S.A. Copyright Gypsum Association 2013. All rights reserved. This document may be revised or withdrawn from circulation at any time. The status of the document should be verified by the user prior to following any recommendations contained herein. To verify that you have the most curre
2、nt edition of the document, access the Gypsum Asso-ciation website at: www.gypsum.org. VAPOR RETARDER OVER WATER-RESISTANT GYPSUM BACKING BOARD (GA-230-13) Water-resistant gypsum backing board (see ASTM C 1396, Standard Specification for Gypsum Board) is designed to be used as a base for the appli-c
3、ation of ceramic or plastic wall tile or plastic fin-ished wall panels in wet areas. Water-resistant gyp-sum backing board shall not be used where there will be direct exposure to water or continuous high humidity conditions. Such areas include but are not limited to saunas, steam rooms, gang shower
4、 rooms, and indoor pools. To avoid the potential for condensation in the wall cavity, water-resistant gypsum backing board used as a base for tile in wet areas shall not be ap-plied over a vapor retarder. Where water-resistant gypsum backing board is the substrate for ceramic tile on exterior walls
5、requiring a vapor retarder, the vapor retarder should be created on the face of the gypsum board substrate as follows: Apply a uniform skim coat, not less than 1/32“ (0.8 mm) thick, of water base Type I ce-ramic tile adhesive (ANSI A136.1) over the water-resistant gypsum backing board. Allow the ski
6、m coat to set or cure before applying the adhesive bond coat and installing the tile. Tests by an independent testing laboratory con-ducted in accordance with ASTM E 96 dry cup method, Procedure A, determined an average water vapor transmission rate of 0.29 perms for this appli-cation method. To mai
7、ntain tile system integrity, periodic main-tenance of grout, caulking, and sealants at penetra-tions is required. Failure to properly maintain these essential system components can result in water in-trusion and subsequent damage to the system. On exterior walls where the tile covers less than the f
8、ull wall surface, a vapor retarder can be pro-vided on the interior surface by applying a vapor retarder paint or primer over the area not covered by the tile. Apply the vapor retarder paint or primer in accordance with the paint manufacturers recom-mendations. AdhesiveBondCoatPlasticorCeramicTileAd
9、hesiveSkimCoatWater-ResistantGypsumBackingBoardNOTE 1: Consult gypsum panel product manufacturer for recommendations regarding the use of specific gyp-sum panel products as a base for tile in wet areas. NOTE 2: The use of water-resistant gypsum backing board as a base for tile in wet areas is regula
10、ted by lo-cal codes. Consult local building codes for require-ments. Gypsum Association Members 2013 American Gypsum Company LLC CertainTeed Gypsum Canada, Inc. CertainTeed Gypsum, Inc. CGC Inc. Georgia-Pacific Gypsum LLC Lafarge North America Inc. National Gypsum Company PABCOGypsum a division of PABCO Building Products, LLC Temple-Inland United States Gypsum Company Gypsum Association 6525 Belcrest Road Suite 480 Hyattsville, MD 20782 (301) 277-8686 (301) 277-8747 fax www.gypsum.org
