There are two spray foam choices: open and closed cell foam.

Open cell foam features millions of foam cells that share cell walls with each other, making it structurally lighter. As a result, open cell foam weighs only about half a pound per cubic foot. Open cell insulation expands up to 100 times its volume sprayed to completely fill the area, including gaps and crevices. Its light weight and outstanding insulating power make it ideal for walls, basements, roofs, and attics in residential and commercial buildings.

Closed cell foam is much denser than open cell. Each cell is independent of its neighboring cells, resulting in a foam containing much more plastic than open cell foam. The result is a highly-efficient insulating foam that weighs about two pounds per cubic foot. Closed cell foam’s denser composition enables it to form an excellent air, moisture, and vapor barrier for residential and commercial structures. Because it contains much more plastic than open cell foam, it is more expensive to use.