Tech Today

Unvented, conditioned attics


Unvented, conditioned attics can be a design alternative to conventional attic ventilation of steep-slope roof assemblies. If you are involved in the design, manufacture or installation of steep-slope roof systems, you should be aware of the unvented, conditioned attic concept, related code requirements and NRCA's guidelines.

Concept

In an unvented, conditioned attic, the roof assembly's thermal envelope (insulation) is repositioned from the ceiling level to the roof plane, resulting in the attic being conditioned. Direct air supply into the attic is not required if the attic floor is not insulated; the temperature will be similar to interior conditioned spaces.

Illustration of an unvented, conditioned attic configuration