Polyisocyanurate is a thermoset plastic typically produced as a foam and used as rigid thermal insulation.  The wet foam is placed against a facing and expands to meet another layer of facing. This foam then becomes tacky as it dries and adheres itself between two aluminium foil facings. Manufacturers can stop this process at any time and cook the board under heat and pressure to achieve the thickness they need. When wet PIR hardens and dries, the board is then cut into different sizes. Manufacturers cure each board in a temperature-controlled space for one day per each 25mm of thickness. The result is a lightweight, durable insulation board that is easy to manipulate and fit. The board is manufactured with agents that have zero ozone depletion potential (ODP) and zero global warming potential (GWP) meaning it is as gentle on the environment as it is tough on cold spots.