I have an 80 y.o. bungalow in Chicago. Attic had no insulation, so went with an un-vented attic and had closed cell foam sprayed into the rafters. Sadly, I failed to have the top-plate foamed at the time. If I pull up the attic floorboards and foam the top plate between the joists from the inside, does this still leave the house vulnerable to stack effect from the exterior? Can I open the soffit and apply closed cell foam to the exterior (home is brick construction) at the location of the top plate, essentially “sandwiching” the plate in foam, and then restore the soffit? The sill plate is foamed in the basement.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
You don't have to sacrifice historical elements of a house in the name of energy efficiency.
Featured Video
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Any opening that allows exterior air into that space would be a leak.
The joist bays at the exterior walls are large areas that only have the sheeting at the exterior of the frame as "insulation". So they should be insulated. Further, there are maybe/probably penetrations or gaps that go down through the top plates and into the wall cavities-perhaps all the way to the basement-barring insulation and / or firestops within the walls.
As far as the soffit area, good question. Without taking a look, it would only be a guess. I think once you take a look from the inside, you might be able to figure if the seal is appropriate and the best action is taken on the inside.
I'm assuming that they did take the foam down to the flooring at the ends of the rafters?