We have a large bedroom above a crawl space. Air is leaking from the crawl space into the bedroom around the bottom of perimeter walls. There are apparently gaps between the floor and the walls. Does anyone have a recommended way to seal off the gaps at the bottom of the walls where the leaks are occurring? I have considered 1) foam; 2) tape. perhaps the best way is to get into the crawl space and do the sealing from there.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
![](https://images.finehomebuilding.com/app/uploads/2024/08/23064822/Larrys-Wall-Construction-thumb-16x9.jpg)
Listeners write in about opera and keeping young by building and ask questions about leaky light fixtures, porch conversions, and installing wood siding.
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
Get a spray foam kit and do it from the underside.
Foam
Thanks for the solution. What kind of spray foam should I use?
Are you sure the air is infiltrating from the crawlspace? Most contemporary houses are built with the stud walls built on top of the floor plywood. This being the case, there is no clear path for air from the crawl to inside the house. But there is a clear path for outside air. If you've got that condition, you'll have to seal from the inside. In that case, removing base trim and using caulk, or possibly foam, is the solution.
I'll bet you've got air coming in around the windows also.
Air Leaks
As you indicate, I could not find a clear path from the crawl space. So I ended up doing as you suggetsed - removal of base trim and using foam. it seems to have worked very well. I used a foam rated for interior use. I also sealed all receptacle and switch boxes.
Thanks for a good suggestion!