Rigid foam insulation for basement
Hi, I recently built a house in southern Wisconsin where the winters get in the negatives and the summers get in the 80’s with very high humidity. I have a partially exposed basement with windows on most walls but I was not planning on finishing the basement off anytime soon. Because I am not finishing it my walls are half foundation and the other half studs. My exterior is Hardieboad on top of Tyvek on top of OSB. And on the inside I had batt insulation between the studs with poly sheeting as a vapor barrier. Because I didn’t put any drywall over the vapor barrier I had a lot of condensation build up on the inside of the wall and poly from the warm inside to the cold outide during winter. I removed all of the poly to prevent mildew (some had already begun) but I wanted to find a way to better insulate my basement than just the batt. I originally considered spray foaming but decided to go with rigid foam instead for a cheaper alternative. My plan is to put 4” rigid foam in between the stud cavities and spray foam around the edges of the foam. Should I be caulking gaps between studs when studs are doubled up next to each other? If I decide to put a layer of 1” or 1/2” rigid foam over the wall against the studs ( in place of drywall) is this acting as a vapor barrier trap because of the rigid foam between the studs? Or am I ok because the foam between the stud cavities has such a high r value?
any thoughts and input would be much appreciated.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part