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Title: Field Testing Unvented Roofs with Asphalt Shingles in Cold and Hot-Humid Climates

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. The Houston-area roof was an unvented attic insulated with spray-applied fiberglass. Most ridges and hips were built with a diffusion vent detail, capped with vapor permeable roof membrane. In contrast, the diffusion vent roofs had drier conditions at the roof peak in wintertime, but during the summer, RHs and MCs were higher than the unvented roof (albeit in the safe range).
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  1. Building Science Corporation, Westford, MA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Technical Report
Research Org:
Building Science Corporation, Westford, MA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
Country of Publication:
United States
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