Hi All -
We are in Upstate NY where winters can be well below freezing with lots of snow and ice and very wet and slushy springs. We are restoring an 1880 Victorian that is quite large, and the walls have never been insulated.
Because the plaster walls were in sich disrepair, we gutted all the exterior walls and now are going to insulate from the inside.
We are very interested in spray foam insulation but the trouble is that we only know "some" of what we should and Im not sure Im entirely comfortable with it. I want to know if my concerns are founder or unfounded, and whether we shoudl do spray foam or not. So here goes
1. We have a contractor who says we should use a 2" thick closed-cell spray foam in all the stud cavities. My concern here is that essentially this creates the vapor barrier on the OUTSIDE wall, and the remaining 4 inches of teh stud bays are open to interior moisture. Could that allow warm moist air to condense on the studs that are colder (due tocold conduction from teh outside), leading to mold and wood rot?
2. It is my understanding that wood needs to breathe, especially if it gets wet. If we do spray foam, then we will end up apply spray foam inslation directly to the back of the house's sheathing (and ins some cases, the original dutch lap siding is nailed directly to the studs, there is NO sheathing). If any water at all gets behind the siding (as in between teh siding and the spray foam), wouldnt it get "stuck there" and be unable to dry out because the spray foam prevents air circulation? We dont have any known major water problems, but this is a huge, 3-story 130 year old house and some water in some amounts, especially during tehice melts in the spring, may enter wallss in places we may never know about. Maybe over the last 130 years water penetration has not been a problem because the extreior walls "breathe," but with spray foam might we introduce a problem in this manner?
3. Related to #2 above, a major concern I have is investing 15-20K in a scraping and brand new paint, only to have it peeling off the siding in 2 years because moisture is trapped in the siding and outgases from beneath the paint because it has no where else to go - on accountof having airtight spray foam insulation.
Any opinions? We are really uncertain about the right way to go.