Closed Cell Spray Foam
Closed cell foam is the work horse of the two foam types. Also
known as two pound (2 lb) foam, it functions as both an air barrier
and a moisture barrier. Moreover, it adds structural strengh and
provides the highest R-value per inch of any insulation.
Closed-cell, or medium-density foam, is a rigid insulating material with a Long Term Thermal Resistance (LTTR) R-value that ranges between 5.1 - 6.9 per inch.
Closed cell insulation can be purchased in rigid boards. However, sprayed or foamed-in-place applications of polyurethane insulation are typically less expensive and perform better because the liquid foam molds itself to all of the surfaces.
All closed-cell polyurethane foam insulation made today is produced with a non-HCFC (hydrochlorofluorocarbon) gas as the foaming agent.