My wife and I are renovating the kitchen of our house on Cape Cod, MA (a cape built in 1979). We took down the two walls that comprised a pantry and now need to repair the drywall on the walls and ceilings where the walls were framed. We’ve repaired some drywall before and have read Myron Ferguson’s excellent book, but there are a few issues that we could use help with. I don’t know all of the construction details but here’s what we see from the inside: there is fiberglass bat insulation between the studs, then (working towards the inside) 1/2″ thick rigid-foam insulation that I think is polyisocyanurate given its color and the fact that I can see what looks like foil on one side, then a poly vapor barrier (not sure how many mils thick), then 1/2″ drywall. The ceilings are similar but have 1″ rigid-foam. I can’t recall whether the foil side is toward the inside or outside (we are not there now). There is some 2×4 blocking between the studs where the walls were. Some questions:
1. I’m assuming that in patching I should try to reproduce what was there. How would I attach the strip of rigid-foam insulation (about 4″ wide) to the blocking? Construction adhesive? Screws? Nails?
2. Would I need to seal the gaps between the rigid foam patch and the existing insulation? If so, what’s the best way to do that?
3. Should I try to tape up the poly vapor barrier? If so how?
4. Does it even make sense to have that poly vapor barrier there if that is actually ISO insulation with foil? I thought the foil served as a vapor barrier.
I have to say the house does seem well insulated and stays pretty warm in the winter (it’s heated with forced hot air). The humidity runs the gamut–very humid in summer, much drier in winter–and we haven’t noticed any issue with mold or rot anywhere so I’m guessing that we don’t have a big problem trapping moisture in.
Thanks and sorry for the long post.
–Rob
Replies
Vapor barrier is also a windstop, to prevent air from entering the building envelope. All seams should be taped. I have cut the foam on a table saw for a nice tight square fit, pressed between the studs. If not some expanding foam should do. Good luck with the renos, hopefully this sets you on the right track.