Vapor barriers help prevent mold and odors. By installing a vapor barrier, the moisture level can be greatly reduced, which will also prevent mold and foul odors from forming. Vapor barriers can help your floor. Since damp soil constitutes the floor of the crawl space, moisture rises to the first floor of the house. An insulated crawlspace will keep floors at comfortable temperatures in both the winter and summer. Vapor barriers can also prevent pipes from bursting.