The best direction is to insulate the knee wall roof deck. You must baffle the roof deck before insulating. This prevents air from degrading the fiberglass and reducing it's R-Value. Also if there is an exposed soffit on the deck of the knee wall make sure to block it and connect it to the baffles under your roof deck.
We insulate it all on this project we used fiberglass batts to insulate the cathedral ceiling area, other projects we have used spray foam insulation. We like to keep your project under budget, and we have many options for you to utilize!
In this picture you see it all! The foil faced fiberglass batts, the Kraft faced fiberglass batts, and the cathedral area! All baffled, before installation. The far wall (in the center) was air sealed before we installed the fiberglass batts!
Knee walls are major weak spots in our homes (some folks call them crawl spaces). These spaces are often used for storage, and right up against your bedroom wall! The best corretion is to baffle and insulate the roof deck area. There are many more tricks that need to be done to disconnect your area from unconditioned air! Call us today and we will get it fixed for ya!