Rigid foam, fiberglass, and wiring
I’m looking at approaches to insulate the attic side of my knee wall. There is currently fiberglass roll insulation between the studs, that continues up the slanted portion of the ceiling, and no air barrier (see attached). I’ve read Martin’s article on the two ways to insulate a knee wall. Ducts are in the attic, which I know is problematic, but I would like to proceed anyway.
I’m thinking about adding 2 inches of rigid foam over the studs, leaving the fiberglass in place. With this approach, my big question is:
What do I do about the wiring in those wall cavities? Is it safe to encase them with insulation? They’re not knob and tube. There are outlets in the knee walls, so wires will have to penetrate somewhere. How do I install the boards, considering the presence of these wires?
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