There are two main types of spray foam insulation available on the market today, each with their own strengths: closed and open cell. Overall, spray foam is superior to other forms of insulation, and closed cell has certain advantages over open cell. The chart below illustrates how spray foam insulation measures up against other types, and how the two types of spray foam compare to each other
How does Spray Foam Compare?
SOURCE : http://www.sprayfoam.com
According to this chart it’s easy to see that closed cell spray foam insulation has the highest R-value of all the types shown. It also has many of the positive features listed above, with the notable exception of being able to act as a certified air barrier. Also, spray foam cannot be injected into existing wall cavities without major demo work. Closed-cell spray foam does serve as a vapor barrier, unlike open cell. Therefore, the location of the walls to be insulated, and their exposure to the elements (water) will be a significant factor in determining which type of spray foam insulation to go with.