Polyisocyanurate or polyiso is a thermosetting type of plastic, closed-cell foam that contains a low-conductivity gas (usually hydrochlorofluorocarbons or HCFC) in its cells. The high thermal resistance of the gas gives polyisocyanurate insulation materials an R-value typically around R-7 to R-8 per inch.
Polyisocyanurate (polyiso) insulation is a thermoset, closed-cell, rigid foam plastic insulation manufactured in board form. Via a continuous lamination process, liquid raw materials that expand and become light (yet strong) are applied between engineered facing materials. These facings provide strength, improve rigidity, and enhance thermal performance.
Polyisocyanurate (polyiso) can contribute to a more fire-safe home or building after renovation work. It passes both American National Standards Institute/Underwriters Laboratories Inc. (ANSI/UL) 1256, Fire Test of Roof Deck Constructions, and Factory Mutual (FM) 4450, Class I Insulated Steel Deck Roofs, without a thermal barrier. Additionally, polyisocyanurate (polyiso) stays intact during fire exposure in ASTM E 84, Standard [Tunnel] Test Method for Surface Burning Characteristics of Building Materials, forming a protective char layer and remaining in place to meet building code requirements.
