Spray Foam Insulation
Spray foam is the most technologically advanced insulation material available. Developed by Otto Bayer in the 1940’s, it was originally used for military purposes. It started being used in the residential market in the 1980’s and has been gaining popularity in that field since.
Spray foam is a spray applied liquid plastic that expands and adheres to the substrate. Unlike batt materials, this allows sprayfoam to properly fill all cavities and prevent gaps. The major advantage spray foam insulation is the fact that they are one of the few products that prevent air movement passing through them.
There are different kinds of spray foam, open and closed cell. The primary difference between these two is density.
OPEN CELL SPRAY FOAM INSULATION
Open Cell spray foam is the less dense of the foam, with a density of .5 lbs per cubic foot. It has an R-value of around 4 per inch. Open cell is not a vapor barrier, meaning it does not completely stop moisture from passing through, but it is an air barrier which stops air movement. At 5.5 inches it is enough to prevent air movement in a roof in order to prevent condensation and ice dams. In addition to insulating, it is decent at deadening sound as well. Open is significantly cheaper (about half the cost) when compared to closed cell.
CLOSED CELL SPRAY FOAM
Closed cell is indeed the Rolls Royce of the insulation materials. With a density of 2.0 pound per cubic foot, it has an R-value of around 7 per inch. Closed cell is not as good at sound deadening as open cell, but it does add a lot of structural stability.