Charles writes from Eliot, Maine: "I have a question about insulating a kneewall. I saw a web site that advocated putting batts between the studs, but then putting rigid foam panels on the back side of the wall (facing the cold air). The idea was to reduce drafts - wouldn't this create a double vapor barrier situation?

If this is a viable idea, would i use r13 or r15 since the studs are 2X4, and then put an inch of FOAMULAR® add generic on the back side?

On the slope section of the wall, could I just use FOAMULAR® insulation offset by furring strips instead of the standard vents? (so, from the inside, itd be sheetrock, vapor barrier, insulation, FOAMULAR® , 2 inches of air, roof sheathing?)"

Answer: When insulating your knee walls, Owens Corning recommends the use of Fiberglas® batts with Kraft facing. The Kraft facing should face the warm-in-winter side of the studs. The use of FOAMULAR® insulation on the cold side of the wall is not recommended. Any moisture that gets past the Kraft paper vapor retarder may condense of the surface on the FOAMULAR insulation.