Building America Webinar: Unvented Attics in Residential Buildings

You are here

During this Building America webinar on May 18, 2017, participants learned about a new innovative technology and new code provisions and resources from leading experts Dr. Joe Lstiburek, the founding principal of Building Science Corporation, and Pam Cole, research scientist with Pacific Northwest National Laboratory.

The new code language requires installation of vapor diffusion ports/vents in unvented attics to allow moisture in the attic to be removed by diffusion rather than by air change. This allows the attic assembly to remain airtight while providing a path for moving the moisture to the outside via vapor diffusion. The requirement, however, only applies to climate zones 1, 2, and 3 when air-permeable insulation is installed. This allows for more flexibility in insulation material choices for designers, builders, and consumers. Additionally, in regions with high wildfire occurrence, elimination of eave vents and air sealing the upper attic vents at ridges significantly decrease entry paths for embers that could start a house fire. In hurricane zones, eliminating roof vents reduces the entry way for rainwater during storms.

The webinar recording is alway available.