Dow Styrospan and Roxul Batts
I have followed a long list of questions regarding closed cell foam, flash and batts etc. None of which quite answered my question. That said, here goes my very first internet posted question!
I have a poured rubble foundation(85 yr old home) in southern ontario…zone 6 or 7? I would like to insulate the walls to R-24. The walls are quite sound save the odd area where I have reparged. I have priced 4″ closed cell foam but I am still very reluctant to go ahead with it for two reasons. Number 1 is the cost and a very close second is the fact that I live in a subterranean termite zone within my city and I do not want to create a protected tunnelling haven for them.
My real question is this. My next best idea is to lay a tar paper membrane against the foundation(or a recommended alternative), followed by R21 roxul then finished with 1-1 1/2″ of foam board sealed individually between the studs. I would not install a vapour barrier but would drywall lastly. This may be more time consuming but it is all removable if need be for inspection. Am I looking at any condensation and frost problems down the road?