What is the difference between open and closed cell foams?
Open cell foam performs two functions; it stops the movement of air and slows down the transfer of heat. Open cell foam products are generally not considered vapor retarders. In climate zones 6-8 a vapor retarder system may be required on the warm side of the insulation relative to the design of the wall or ceiling system. Closed cell foams, on the other hand, have low vapor permeate due to their cell structure. These foams, depending on thickness, may be considered a vapor retarder but not a vapor barrier. Closed cell foams also have a high compressive strength which allows them to be used for exterior applications. Open cell foam should never be used for exterior applications. Open cell foam are usually more cost effective because of their higher yields. Please work with your local Certified Biobased dealer to determine which product works best for your specific application.
