How can I insulate an open crawl space under an existing finished room?
I want to insulate under an existing finished room. The room’s foundation is pressure treated post and beams. The previous use of the room was a screened porch/deck. I was planning to frame the exterior walls and insulate. I was planning to install OSB sheathing, House wrap, Rigid foam, wood furring strips an finish with vinyl siding. There is an existing basement window that could be opened to this space. The space in the floor joist has fiberglass batts, kraft paper up toward the finished room and Homosote on the underside of the joist (exterior underside finish). Is ventilation a concern? The height varies from approx. 2′ to 3′.
Thanks
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Replies
Mike,
It can be tricky to enclose a crawl space under a room with a pier foundation. The right way to do it is to excavate below the frost line, pour concrete footings, and then pour concrete stem walls to support the room above. That's expensive.
You can enclose the area with halfway measures -- for example, pressure-treated studs and pressure-treated plates, with the plates sitting on dirt, and cement backerboard sheathing over rigid foam -- but this type of enclosure (a type of skirting used for mobile homes) isn't very permanent.
What problem are you trying to solve?
Martin,
My goal was to limit the cold air under the room. I think I had the same concern as you do, How permanent will it be. Would I be better served by installing the rigid foam to the underside of the Homosote or am I wasting my time and money? As compared the benefits.
Thanks