I’m getting ready to insulate a crawl space. It has a concrete slab. I’m trying to decide between insulating the foundation walls or the underside of the floor, between the joists. If I go between the joists, do I install a vapor barrier? If so facing up or down?
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If you are in the North ( cold areas such as Michigan or Ohio or New England) , I would use rigid insulation attached with adhesive on the foundation walls and thenfiberglass bat insulation 6 inchs thick (r-19) stapled between the joists. In the North the vapor barrier goes to the warm space, so put it in place as 6 mil plastic before you add insulation( staples will hold it). Use chicken wire or hardware cloth to keep fiberglass from falling back out. DO NOT COMPRESS the fiberglass batts.
All of this is BAD ADVICE if you live in Texas, or Florida or somewhere in the South.
Do you have any ducts and or plumbing running in the crawl space under the floor joists? If this is in the north, insulate the perimeter walls with ridig insulation as much as you can. Be sure to have a supply register open in the crawl heating the area for the plumbing. If you have no plumbing, but have ducts, be sure to have the ducts also insulated, not only the floor. All of this once again, only works if you in the midwest or further north.
HI Nrosen,
What did you decide to do in your crawlspace and how did it work out? I'm in a similar situation now and trying to decide what to do.
Thanks