Rigid foam roof insulation and polyethylene vapor barrier inside — problem?
Was planning on a r-25 insulated roof deck for a ski house in lower zone 6 NH with cold roof (strapping with plywood) on top of that to help prevent ice dams.
Existing cathedral ceiling is actual 8″ rafters framed 24″ o.c. with 6″ paper faced fiberglass batts. In exploring the original construction (circa 1980) I also found a layer of POLY as an additional vapor barrier….which sabotages my R-25 rigid foam roof plan…..damn.
Considering cutting sections of plywood roof deck out in strips (? on width) to try and sabotage the existing poly and render it ineffective…….Is this a sound plan or pipe dream?
Hoping someone out there has an experience in removing existing fiberglass in catherdral ceiling from the topside that they would like to share. I would like to dense pack the rafter bays after roof deck is insulated.
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