This specification covers the minimum requirements for and the methods of application of gypsum sheathing for use as a substrate for exterior wall cladding. Gypsum sheathing board is a substrate that shall be covered by an exterior cladding or other weather-resistive barrier and is not intended for long-term exposure. Framing members shall be installed so that the surface will be in an even plane, unless otherwise specified, after the gypsum sheathing has been applied. The gypsum sheathing shall be cut by scoring and breaking or by sawing, working from the face side. The cut edges and ends of gypsum sheathing shall be trimmed to obtain neat fitting joints when installed. Gypsum sheathing shall be fitted snugly around all window and door openings. Control joints, other accessories, and metal plaster base shall be fastened through gypsum sheathing to framing members. Where fire resistance or shear resistance is not required, and when metal lath and Portland cement plaster are to be applied as the exterior cladding over gypsum sheathing installed over framing members and the metal lath shall be installed after the gypsum sheathing, the gypsum sheathing shall be permitted to be applied and fastening of the gypsum sheathing shall be completed with the attachment of the self-furred metal lath.

1.1 This specification covers the minimum requirements for and methods of application of exterior gypsum panel products that are specifically designed for use as a substrate for exterior cladding.

1.1.1 This specification does not cover gypsum panel products that are specifically designed for interior applications.

1.2 Details of construction for a specific assembly to achieve the required fire resistance shall be obtained from reports of fire-resistance tests, engineering evaluations, or listings from recognized fire testing laboratories.

1.2.1 This specification shall govern where it is more stringent (size or thickness of framing and size and spacing of fasteners) than the fire-rated construction.

1.3 Where sound control is required for a gypsum panel product assembly, the details of construction shall be in accordance with the acoustical test report of an assembly that has met the required acoustical value(s).

1.3.1 This specification shall govern where it is more stringent (size or thickness of framing and size and spacing of fasteners) than the sound-rated construction.

1.4 Where resistance to racking loads or shear is required for a gypsum panel product assembly, the details of construction shall be in accordance with the racking or shear test report of an assembly that has met the required racking or shear value(s).

1.4.1 This specification shall govern where it is more stringent (size or thickness of framing and size and spacing of fasteners) than the racking or shear-tested construction.

1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.6 The text of this standard references notes which provide explanatory material. These notes shall not be considered as requirements of the standard.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.