Crawl Space Insulation - Vapor Barriers
The vapor barrier installed in most homes at construction or inspection for sale is a 6-mil. It is a flimsy material, similar to a trash bag. Its purpose is to protect the crawl space from the earth's moisture. However, when a 6-mil is installed, it is typically laid on the ground and U shaped pins are pushed through it to help keep it in place, creating holes where moisture can get in and weak spots that make the material easier to tear. The seams are not sealed, and the liner just runs to the wall, leaving the crawl space exposed to the earth's moisture. These 6-mil "barriers" do little to protect the crawl space from the earth's moisture and are easily torn and displaced.