The best way to insulate a crawl space is to turn it into an UNVENTED
space. To do that, you will first need a vapor barrier on the floor
(especially if it is dirt) using 6 mil plastic, taped at the seems.
Masonry walls, plates, and other leak points can be sealed with 2
component expanding foam (material costs are NOT cheap). You can do
the joists above. To save money, I would recommend you have the crawl
space joists netted and filled with cellulose. Urethane foam give you
better insulating value, but the costs/benefit ratio is wacked for the
joists due to the high cost of foam.




Steve Silberberg wrote:
Hi,
I live in the Boston area My house has no basement, just a
crawl space between the main floor and the ground. The batts of
insulation beneath the floor are drooping or worse so that there's
nothing between the breezy crawl space and the floor.

I had a guy come over and he suggested that instead of roll
insulation, I have foam sprayed between the joists to form a hermetic
seal.

Question: Is this a good idea? I like that fact that winter
winds will no longer whip up through my floor, but will the hermetic
seal cause a moisture problem under the house in warmer, wetter times?

Many thanks in advance.
Steve

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Steve Silberberg

Read "We'll Kiss For Food"
http://www.kissforfood.com/