As residential construction has slowed over the past few years, many insulation contractors have turned to weatherization projects that add insulation and air sealing to existing homes. For SPF contractors, one of the easiest and most accessible areas to insulate and air seal is the band joist and to create unvented attics and crawlspaces.
Unvented attics can be easily created by applying foam directly under the roof deck between and over the rafters. This provides a continuous layer of insulation at the roofline. When existing soffit and ridge vents are sealed off, this application can make for an attic space that is inside the building envelope and tightly sealed against air leakage. The main question for spray foam and other weatherization contractors is how to deal with the existing insulation installed on the attic floor.