Square Edge PIR Cavity Wall Insulation 1200x450mm is fibre free rigid polyisocyanurate insulation with an aluminium foil coating. The high performance insulation is used within traditionally built masonry walls. The boards match with brick and block dimensions to allow the insertion of wall ties at the appropriate spacing. It is a stable and durable board with a resistance to solvents, water vapour and rotting. The reflective foil surface can cut radiated heat transfer across an adjoining air-space.