What is CLOSED-CELL FOAM? If your aim is to learn about spray polyurethane foam insulation, you're on the right page. Before going forward with a spray foam application on either a commercial or residential building, it is important to establish whether you will utilize 2.0 lb./cu. ft. closed-cell foam. Best CLOSED-CELL FOAM insulators in Fort worth There are chief factors to consider when it comes to differentiating open cell and closed-cell foam. First off, it is important to examine each type of foam. With open-cell foam, the minuscule cells of the foam are not entirely closed, so the foam itself is permeable and can fill with air and moisture. These tiny open spaces render the foam weaker and softer feeling than closed-cell foam. Closed-cell foam has a greater resistance to water vapor and air leakage, it is stronger, and has a higher R-value than closed-cell foam. However, because closed-cell foam is higher in density, it requires more material than open-cell foam