Air sealing an attic kneewall
I watched the GBA video: Air sealing an attic kneewall
The approach used in the video is opposite to what I am thinking of doing. My approach: 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, followed by drywall.
In the video, it shows batt insulation in the kneewall studs, then a piece of polyisocyanurate foam on the attic side of the kneewall. Explanation offered in the video is that: “the insulation in the knee walls of an attic is usually uncovered on the attic side. That has the potential to degrade the insulation as convective air loops through the insulation.”
Now i’m wondering if the approach I was thinking of using is flawed and needs to be adjusted. Please advise. Thanks.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part