air sealing detail for basement slab
I have a basement slab that is poured on top of extruded polystrene foam. There is also 1″ of foam around the perimeter of the foam to isolate the slab from the foundation walls. I would now like to air seal that gap so I don’t get cold air flowing in and so that my passive/active radon mitigation system performs as it should. Any recommendations on sealing this gap effectively and affordably?
Replies
The 1" foam around the perimeter should be an air seal in and of itself. If you want to further seal the foam I would use a small rasp to reduce the foam height to about 1/4" below the level of the slab. Then use a self leveling caulk like SL1 over the foam.
That is what I did on a building I put up for my wife, but my perimeter foam was 2". Not pretty for a finished floor, but it worked well.
Dave