Im a little confused about Vapor Barriers

March 11th 2002

Dear Shell,

I'm a little confused about Vapor Barriers.

I have built a 900 sq.ft addition attached to my 1200sq.ft. bungalow. It has forced air heat, and I have heat ducted into the crawl space to heat it as well. I have been told that I should use fiberglass insulation in the space between the grade beam and the floor, then place the vapor barrier, sealing it to the bottom of the floor and at any joints. Then install 3" Styrofoam insulation against the inside of the grade beam, and on the floor of the crawl space, in from the grade beam at least 36" inches.

I always thought insulation had to be on the cold side of the vapor barrier. Does the method I described make sense?


Kent (Lorette, MB)

Dear Kent,

Rather than get into a long and complicated answer, I’d like to refer you to an excellent publication that deals specifically with this issue. Crawlspace insulation and related details are covered in a booklet entitled “Consumers Guide to Keeping the Heat In”. This is a free publication from Energy Mines and Resources. Please call 1-800-387-2000 for your free copy to install requested information. The booklet has great advice and diagrams that will walk you through the proper process.

It’s just that easy

Shell Busey