Closed Cell Insulation
Closed cell insulation is a type of spray foam insulation. Unlike open cell insulation, closed cell insulation does not fill with tiny air pockets and expand. It has a smaller, more compact cell structure. Thus it is much denser than open cell insulation and provides a higher R-value than open cell insulation.
Closed cell insulation is a very good barrier against both air and water vapor. Because it is so dense, it can help add strength to the structures to which it is applied. It is commonly applied to roofing and other outdoor projects. Because of these properties, closed cell insulation is also most often applied to shallow spaces as well.