Closed Cell Foam
The advantages of the closed-cell foam compared to open-cell
foam include its strength, higher R-value, and greater resistance to the
leakage of air or water vapor. The disadvantage of the closed-cell foam is that
it is more dense, requiring more material, and therefore, more expense. Even
though it has a better R-value, the cost per R is still higher than open-cell
foam. The choice of foam should be based on the requirements for the
other characteristics - strength, vapor control, available space, etc...