Attic finishing & proper insulation
I am currently refinishing the attic of my 1955 Cape style house into a new bedroom. The roof joists are 2×6 construction, no vents other than two soffits installed by contractors last year as part of an energy audit. The room is being constructed with knee walls, leaving crawl spaces on either side of the room, and has about 600ft^2 of total ceiling (probably about 400-500ft^2 of living area?) for insulation. We had a relative, who is an architect, draw us up some plans for building and insulating, and now that I’m almost at the insulating stage I’m trying to make sure I understand what’s going on, and minimize cost and potential hazards.
What he suggested we do for insulation was 1 inch of closed cell spray foam, followed by the denser fiberglass batting to fill the rest of the void, and then apply rigid foam board of about 1inch – 1.5 inches over the joists. But after reading a few things here, and on other sites, will this leave me with any moisture control issues? And how will the crawl spaces behind the knee walls affect my moisture control? Do I need to use rigid foam board in the crawl spaces, or could I simply use thicker batting?
Note: the picture I’ve included is pre-framing (we’re about 90% done now), and the knee walls begin approximately where the plywood in the picture ends, if that helps at all.
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