1.1 This specification covers the gypsum boards described in 1.1.1-1.1.9.

Specifications C 840, C 841, C 844 and C 1280 contain application procedures for gypsum board.

1.1.1 Gypsum wallboard designed for use on walls, ceilings, or partitions and that affords a surface suitable to receive decoration.

1.1.2 Predecorated gypsum boarddesigned for use as the finished surfacing for walls, ceilings, or partitions.

1.1.3 Gypsum backing board, coreboard, and shaftliner boarddesigned for use as a base in multilayer systems or as a gypsum stud or core in semisolid or solid gypsum board partitions, or in shaft wall assemblies.

The terms backing board, coreboard, and shaftliner board refer to different end uses. The term gypsum backing board, as used in this specification, shall include gypsum coreboard and gypsum shaftliner board unless otherwise stated.

1.1.4 Water-resistant gypsum backing boarddesigned primarily to be used as a base for the application of ceramic or plastic tile on walls or ceilings. This product is also suitable for decoration.

1.1.5 Exterior gypsum soffit boarddesigned for use on exterior soffits and carport ceilings that are completely protected from contact with liquid water.

1.1.6 Gypsum sheathing boarddesigned for use as sheathing on buildings.

1.1.7 Gypsum base for veneer plasterdesigned for use as a base for the application of gypsum veneer plaster.

1.1.8 Gypsum lath designed for use as a base for the application of gypsum plaster.

1.1.9 Gypsum ceiling boarddesigned for use on interior ceilings with framing spaced not more than 24 in. [610 mm] on center and that affords a surface suitable to receive water-based texture and other decoration. This product is also suitable for use on interior walls.

1.2 Specifications applicable to all gypsum boards are located in Section and . Specifications applicable to specific gypsum boards are located in the following sections:

1.3 The values stated in either inch-pound units or SI (metric) are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system shall be used independent of the other. Values from the two systems shall not be combined.