Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I have a large room in my house that is built over a crawl space. The floor of this room does not have any insulation installed in it. I live in upstate New York so it is my understanding that I should install a vapor barrier on the interior side of the insulation (the warm side). It seems like it would be very difficult to get the vapor barrier up against the floor from below.

Should I skip the vapor barrier? Or is there some other method I could use for this kind of retrofit?

share|improve this question
1  
What type of insulation are you thinking about using? I wonder if you get spray foam so it makes an air-tight seal if that would work as a vapor barrier. –  auujay Sep 5 '11 at 3:10
add comment

1 Answer 1

up vote 0 down vote accepted

The vapor barrier for a crawl space belongs above the floor joists and below the sub floor. You pretty much have three alternatives here.

1) Remove all the flooring - including the subfloor - install the vapor barrier - and replace the flooring, except you'll pretty much have to destroy the flooring in the process.

2) From underneath, take 6 mil plastic and set it into each space between the floor joists. You can then either wrap the plastic tightly around each floor joist, stapling it in place and then taping over the staples, or you can cut the plastic so that it doesn't wrap the floor joists, and tape each cut edge.

3) Buy spray foam and use it as both the vapor barrier and insulation. For this application you would want the fire rated open cavity foam like what they sell here: http://www.tigerfoam.com/products.php

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.