Unvented Roof Celulose

Air permeable insulation such as fiberglass batts dense packed cellulose or blown in fiberglass can t be used alone for an unvented assembly since these types of insulation can allow moist indoor air to reach the cold roof sheathing leading to condensation or moisture accumulation in the sheathing.

Unvented roof celulose. We agree that avoiding sheathing rot is critical and that air permeable insulation such as fiberglass or cellulose cannot be used alone. Foam free don t stay stuck in the sci finightmare of foam foam foam. Unvented cellulose advanced energy did a mockup of a roof several years ago that include 1 2 osb tarpaper and shingles. We re big fans of fine homebuilding.

Code change allowing use of air permeable insulation in the construction of unvented conditioned attics. Of unvented roofs by more than 50 percent and allow the use of dense pack cellulose in retrofit applications without risk. Near term the moisture content of the roof sheathing b. Address wet basements or crawlspaces before insulating your roof.

In the most recent issue of fine homebuilding martin holladay wrote a piece on insulating unvented roof assemblies. They got it wet and then turned on sunlamps to simulate the sun. When you dense pack an unvented roof here are factors to control for quality and performance. Do not install cellulose below active roof leaks.

Pull out any existing fiberglass or make sure that you can dense pack the cellulose to the outside. In 4 seconds the humidity was coming through.