Rigid Insulation is a foil-faced polyisocyanurate (PIR) insulation board. The PIR board is formed by a continuous foaming process, which gives the board its tight cell structure and bonds the facing to the foam. After foaming the boards are cut to size and left to cure.
It’s a material used to provide thermal resistance to roofs, walls and foundations and is available in formed or extruded sheets of varying sizes, which are made from or polyurethane, polyisocyanurate or polystyrene.