Field Testing of an Unvented Roof with Fibrous Insulation, Tiles, and Vapor Diffusion Venting
- Building Science Corporation, Westford, MA (United States)
This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design.
- Research Organization:
- Building Science Corporation, Westford, MA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B) (Building America)
- OSTI ID:
- 1239735
- Report Number(s):
- DOE/GO-102016-4764; 7316
- Country of Publication:
- United States
- Language:
- English
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Field Testing of an Unvented Roof with Fibrous Insulation, Tiles, and Vapor Diffusion Venting