Vapor Barrier- in Crawl Space Insulation


Old 10-06-03, 07:31 PM
Thread Starter
Join Date: Aug 2001
Location: USA
Posts: 19
Received 0 Votes on 0 Posts
Vapor Barrier- in Crawl Space Insulation

Argument ensued over vapor barrier placement in floor joists over crawl space. No vapor barrier over bare earth. Insulation placed between joists with paper facing down-(ie) away from floor with paper flanges stapled to bottom of joists. Contractors said it's always done this way. I say paper goes next to floor- toward the heated side. Please advise proper method.
Ol' Guz
Sponsored Links
Old 10-06-03, 08:57 PM
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: USA
Posts: 1,875
Received 0 Votes on 0 Posts

This is a Dept.of Energy brief on vapor barriers. It clearly states that the vapor barrier in your area should face the warm side of the house, which means when installed in a crawlspace, the paper faces the subfloor. This also means you cannot staple the vapor barrier to the floor joists.

The ground cover for your dirt floor in this crawl space is known as a moisture barrier. The difference between a moisture barrier and a vapor barrier is vapor barriers deal with diffusion and moisture barriers deal primarily with capilliary action. In other words, moisture barriers do not have to be vapor barrier rated.
Old 10-08-03, 11:08 AM
Ed Imeduc's Avatar
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389
Received 0 Votes on 0 Posts
crawl way

Like resercon said. That builder you have sure has it wrong. You want a good 6 mil poly down on the ground over lap 2' and tape the seams. go up the wall 2' with it. Put a 2" polystyrene on the walls up to the joist. In the joist space there on the sill plate put cut blocks of R 19 all around the home. If you have the duct work down there we put small outlets in it ED
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: