Polyurethane is a polymer. Polyurethane polymer is formed by process of step-growth polymerization. In this reaction a monomer containing at least two isocyanate functional groups reacts with other monomer containing two hydroxyl groups in the presence of a catalyst. Polyurethanes are mainly used in rigid foam insulation panels, high elasticity flexible foam seating, microcellular foam seals etc. Fully reacted polyurethane polymer is chemically inert. Spray foam is used for thermal insulation of residential and commercial buildings. It is basically of two types’ closed-cell foam and open- cell foam. Closed-cell foam are those in which all of the tiny foam cells are closed and packed together with all cells filled with gas where as in open- cell foam tiny cells of the foam are not completely closed and are broken with air filled in open spaces. The gas filled in close cells helps foam to rise and expand making it better insulator as compared to open cell foam also Closed-cell polyurethane foams are rigid and have greater material strength than open cell Polyurethane foam.