Technology Solutions Case Study: Application of Spray Foam Insulation Under Plywood and OSB Roof Sheathing

Program Document · Fri Nov 01 04:00:00 EDT 2013

OSTI ID:1220959

Spray polyurethane foams (SPFs) have advantages over alternative insulation methods because they provide air sealing in complex assemblies, particularly roofs. Spray foam can provide the thermal, air, and vapor control layers in both new and retrofit construction. Unvented roof strategies with open cell and closed cell SPF insulation sprayed to the underside of roof sheathing have been used since the mid-1990s to provide durable and efficient building enclosures. However, there have been isolated incidents of failures (either sheathing rot or SPF delamination) that raise some general concerns about the hygrothermal performance and durability of these systems. The primary risks for roof systems are rainwater leaks, condensation from diffusion and air leakage, and built-in construction moisture. In this project, Building Science Corporation investigated rain and built-in construction moisture and vapor drives. Research involved both hygrothermal modeling of a range of rain water leakage scenarios and field evaluations of in-service residential roofs. Other variables considered were climate zone, orientation, interior relative humidity, and the vapor permeance of the coating applied to the interior face of open cell SPF.

• Research Organization: Building Science Corporation (BSC)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B) (Building America)
• OSTI ID: 1220959
• Report Number(s): DOE/GO-102013-4255; 6548
• Country of Publication: United States
• Language: English

Related Subjects

BSC
Building America
OSB
Residential Buildings
closed cell
hygrothermal modeling
moisture content
open cell
plywood
residential
roof
roof sheathing
spray foam