How To Insulate A Knee Wall Attic

The floor of the room with the knee wall is typically connected to the attic.

How to insulate a knee wall attic.

Air sealing and insulating the knee wall can make the attic space warmer more efficient and more comfortable. Be sure to notch the rigid foam over the floor joists and run it all the way down to the drywall or plaster or tuck separate 2 by or foam board blocks between the joists to provide air stops in the joist bays and seal all gaps with canned foam or caulking. If your attic has knee walls install insulation only in the rafters above the knee wall. Keep the attic outside insulating a kneewall and the attic floor behind the kneewall is possible but tricky.

The specific r value for the insulation you need. Now that the kneewall is. The other is spraying at least 2 of closed cell spray foam directly onto the roof deck encapsulating the rafters. Lay each unfaced strip of insulation between the.

Install insulation without misalignments compressions gaps or voids in all knee wall cavities. Then either fiberglass batts secured in place or netted cellulose is used to fill the rafter cavities. Cut unfaced batt insulation to fit between the floor joists in the space behind the knee wall. Use an r value map to determine the amount of insulation you need.

More details online 1. Knee walls leak heat in at least 2 ways. Install an air barrier on the exterior of attic knee wall insulation and to block open floor joist cavities under attic knee walls. Install a top and bottom plate or blocking at the top and bottom of all knee wall cavities.

In this case after insulating the stud cavities with fiberglass batts use 1 inch minimum rigid foam insulation to cover the back of the knee wall which will prevent attic air from circulating around and through the insulation. Bring the attic inside insulating between the rafters simplifies the air sealing details. Through the floor joist.