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Title: Technology Solutions Case Study: Field Testing an Unvented Roof with Asphalt Shingles in a Cold Climate

Test houses with unvented roof assemblies were built to measure long-term moisture performance, in the Chicago area (5A) and the Houston area (2A). The Chicago-area test bed had seven experimental rafter bays, including a "control" vented compact roof, and six unvented roof variants with cellulose or fiberglass insulation. The interior was run at 50% RH. All roofs except the vented cathedral assembly experienced wood moisture contents and RH levels high enough to constitute failure. Disassembly at the end of the experiment showed that the unvented fiberglass roofs had wet sheathing and mold growth. In contrast, the cellulose roofs only had slight issues, such as rusted fasteners and sheathing grain raise.
Publication Date:
OSTI Identifier:
Report Number(s):
Research Org:
Building Science Corporation
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B) (Building America)
Country of Publication:
United States
DOE/Residential; Residential Buildings; BSC; Building America; Unvented attic; Conditioned attic; Inward drive; Cellulose; Dense-pack cellulose; Roof insulation; Roof retrofit; Asphalt shingles; Cathedralized roof; Insulation; ASHRAE 160