Air Seal Attic Knee Wall

1000 2000 cfm50 reductions are fairly common with this method.

Air seal attic knee wall.

The main purpose of this material is to seal the fiberglass batts. Installing batt insulation that extends into the attic past the 2 4 studs making sure it doesn t flop over into the attic by adding some kind of bracing and then adding a 2 piece of rigid board insulation on the non attic side of kneewall. I watched the gba video. Despite all the bad publicity reflective insulation is getting lately i like to use it quite a bit on knee walls.

This will help reduce the wind damage on the insulation to keep it in. Insulation air sealing. Knee walls are among the biggest air leakage and heat loss sources in home in part because they are such a pain in the rear to insulate and air seal properly. Anytime i conduct an energy audit of a cape cod or 3 story colonial or a salt box i know that a good chunk of the homeowner conversation and audit report will deal with the knee walls.

Knee walls have r 13 fiberglass rolls also called batts in them covered with stapled on reflective insulation. I recently had an energy audit done and the auditor gave me a quote for air sealing the attic sealing top plates and any wire plumbing and lighting penetrations. How to air seal knee walls along the roofline. A job we finished last week dropped from 4060 to 2150 cfm50 just with knee wall air sealing we were able to get 8 of one wall that had no top plate.

Properly sealing and insulating attic knee walls can significantly reduce air leakage and heat loss between the conditioned space and the unfinished attic. Insulate and air seal the ceiling of the attic room. How to air seal a knee wall in a cape. The blue wall in the picture below is the knee wall.

An attic access that is perpendicular to the floor. But then for the knee wall it s important to air seal the wall with tyvek or foamboard. Video done by arlington home energy efficiency team during a weatherization barnraising in march 2010. Continue the insulation along the roofline to the roof edge figure 1.

I call this tin foil on steroids because that s what it is. There are arguments about shingle life over a hot roof vs vented but shingle color is more significant and as already stated one can install ventilation chutes. Air sealing an attic kneewall the approach used in the video is opposite to what i am thinking of doing. This number was in additional to the costs to insulate and air seal the knee wall and provide additional blown in insulation.

It is important to choose an air barrier and insulation material that will reduce the air leakage and heat loss as much as possible. From the inside of the attic a knee wall looks like the image to the left.