Finishing An Unvented Attic

If your home is smaller than other homes in your area or simply lacks the necessary amount of storage or living space for your family finishing your attic is a relatively inexpensive way to increase your usable space.

Finishing an unvented attic.

Code requirements vary across the country. For unvented attics having the spray foam layer applied continuously from the roof wall intersection to the roof peak at the specified thickness encapsulating the entire interior surface area of the attic will hinder airborne moisture entry while providing an energy efficient environment. With unvented attics the air barrier vapor and thermal controls are installed at the roof deck. The acceptance of unvented conditioned attics continues to grow among builders and building officials.

An alternate to spray foam insulation in an unvented attic is plenum trusses which allow you create a reverse bulkhead above the ceiling plane that is insulated. The same conditions apply for moisture. By moving the vapor control layer to the roof deck it prevents moisture related problems. A fundamental requirement of an unvented attic assembly is the use of air impermeable insulation on the underside of the unvented roof to prevent air infiltration and exclude airborne moisture from the attic.

The roof deck in an unvented attic must be exceptionally airtight. Residential unvented attics. Coverage gaps could lead to moist outdoor air entry. This reduces latent air conditioning loads and provides further reductions in energy consumption.

An attic is simply the space between a pitched roof deck and the rest of the house. This allows you to install your bulkheads above the ceiling plane without the need for spray foam insulation. The irc has permitted unvented conditioned attics since 2006 with certain requirements. Traditionally we place hvac and ductwork and often storage up there and insulate the floor of the attic.