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Crawl space vapor barrier + rigid wall insulation?

Crawl space vapor barrier + rigid wall insulation?

Old 09-25-11, 06:27 PM
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Join Date: Mar 2006
Location: USA
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Crawl space vapor barrier + rigid wall insulation?

Previous owners were venting dryer into crawl
The existing vapor barrier (looks like 4 mil) and joists COVERED w/ lint
I have vac'ed the lint out the joists and plan to roll the old stuff out and lay down new 6 mil

I read about putting rigid insul and then running the VB up the wall 6-12"
Is the rigid insul necessary?
Can I just run the VB up the concrete?

Also I read some say to leave gaps at the perimeter, some say run it up the walls and seal it. Which is it?

Thanks all
Old 09-25-11, 06:52 PM
Join Date: Oct 2008
Location: New England
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Here is some reading, but basically the walls depend upon the floor insulation. If the ceiling of the crawl is not insulated or if there is equipment down there and exposed water pipes, then install a minimum of 1" rigid on the crawl walls. Also seal and insulate the rim joist. And yes dress the floor VB up the walls. Photo #5 in the link is what you want .

BSI-009: New Light In Crawlspaces — Building Science Information


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