Paper-faced gypsum sheathing is a gypsum board that is used as a substrate for exterior claddings. It has a noncombustible core, composed essentially of gypsum and is faced with water-repellant paper on its back, front and wrapped edges. It is manufactured with either a square or a tongue-and-groove edge.
Gypsum sheathing is manufactured to meet the requirements of ASTM C 79 (C 1396), "Standard Specification for Treated Core and Nontreated Core Gypsum Sheathing Board." It is not intended for use as a long-term exposed material and must be covered with a cladding.