Avoiding the Perils of Paper-Faced Exterior Gypsum Sheathing

February 27, 2005
Publication: Construction Specifier v 58 n 2 p 65-69
Author(s): Eric Olson

Abstract: Buildings must be free of significant mold growth to protect the health of the occupants and the building. However, many in the design/construction industry continue to specify and use products that can deteriorate and sustain mold growth under prolonged exposure to moisture, such as paper-faced exterior gypsum board. Moisture-related problems that can fuel mold growth on paper-faced gypsum sheathing include exterior walls left unprotected against weather for extended periods during construction, high interior humidity, or water leakage into the building. Not only is the subsequent replacement of mold-contaminated exterior sheathing costly and disruptive, but it can also require demolition/reconstruction of the overlying exterior cladding system.  

Designers cannot control many of the factors that may lead to moisture-related deterioration of paper-faced exterior gypsum sheathing. Therefore, designers and specifiers are urged to specify moisture-resistant materials, such as concrete masonry units (CMU) or glass fiber-faced exterior gypsum sheathing, to provide some “forgiveness” if the interior of the wall is subjected to the conditions that cause prolonged water exposure. The article illustrates the risks of using paper-faced exterior gypsum sheathing with real-world examples of mold and moisture damage and discussion of repair work required to correct these issues.