1.1 This specification covers fiber-mat reinforced cement substrate sheets manufactured to be dimensionally stable and suitable as either an unfinished substrate (see Note 1) or as a substrate for decoration such as natural stone or tile in internal wet and dry areas.

1.2 This specification is not applicable to asbestos-cement flat sheets (Specification C220); non-asbestos fiber cement flat sheets for exterior applications such as claddings, facades, curtain walls, and soffits (Specification C1185); gypsum backing board and coreboard (Specification C442); water-resistant gypsum backing board (Specification C630); glass mat gypsum backing board (Specification C1178); particle boards (Definitions D1554); and discrete non-asbestos fiber cement interior substrate sheets (Specification C1288).

1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for information only.