Attic Knee Wall Insulation

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.

Attic knee wall insulation.

The third point is the knee wall and crawlspace floor drywall. Then you can add atticfoil on top of the traditional insulation by stapling it to the wall studs. First you will want to add traditional insulation between the studs this can be batt insulation spray foam or even rigid foam insulation. 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.

There are two ways to insulate triangular attics behind kneewalls. The traditional approach is to insulate the kneewall and the attic floor behind the kneewall. This includes built ins recessed lights vent fans duct work and electrical outlets. Knee walls have r 13 fiberglass rolls also called batts in them covered with stapled on reflective insulation.

This method can be made to work but the necessary air sealing details are demanding and fussy. How to insulate knee walls. Rigid air barrier material could include rigid foam insulation drywall plywood or osb among others. The fourth point is between the roof rafters over the knee wall top plate.

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.