Attic Knee Wall Insulation

The third point is the knee wall and crawlspace floor drywall.

Attic knee wall insulation.

Any penetration between the conditioned interior air and the knee wall space needs to be sealed tight. A better approach is to insulate the roof slope above the attic. This includes built ins recessed lights vent fans duct work and electrical outlets. The fourth point is between the roof rafters over the knee wall top plate.

Insulating only the attic roof rafters and the walls at the end of the attic is one method some use to insulate the knee wall area underneath but carson dunlop author of principles of home. First you will want to add traditional insulation between the studs this can be batt insulation spray foam or even rigid foam insulation. The main purpose of this material is to seal the fiberglass batts. This method can be made to work but the necessary air sealing details are demanding and fussy.

There are two ways to insulate triangular attics behind kneewalls. Install a continuous air barrier on the exterior side of the attic knee wall framing with a rigid air barrier or other supporting material to prevent the knee wall cavity insulation from sagging and to create a continuous thermal barrier. I call this tin foil on steroids because that s what it is. Knee walls have r 13 fiberglass rolls also called batts in them covered with stapled on reflective insulation.

Knee walls that share space with a conditioned room in your home should have a combination of both traditional insulation and foil radiant barrier insulation. How to insulate knee walls.