BA-1409: Field Testing Unvented Roofs with Asphalt Shingles in Cold and Hot-Humid Climates

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In cold climates, a common practice of the weatherization industry is to retrofit compact roof/ceiling assemblies with blown-in dense-pack cellulose. However, this assembly has high moisture and durability risks (due to wintertime interior-sourced condensation) and violates building code. Developing methods to retrofit dense pack insulation into compact roof assemblies while controlling moisture risks would allow for widespread application of this lowcost technique without potentially compromising building

In hot-humid climates, HVAC equipment is typically located in vented, unconditioned attics, with associated energy penalties; one method of moving the ductwork inside the conditioned space is to insulate at the roof deck. However, market penetration of this method has been slow, due to the expense of insulating at the roof line, typically using polyurethane spray foam. If roof assemblies with fibrous insulation could be developed that control moisture risks, this would likely reduce the first cost of unvented roofs, potentially increasing their adoption.

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