EnergyGuard Polyiso Insulation board is made of glass fiber-reinforced cellulosic felt facers bonded to a core of isocyanurate foam. This Polyiso Insulation manufactured in plants use the latest technology in manufacturing to provide a product of the highest quality. Tapered polyiso insulation provides a logical and economical answer for roofs that do not permit adequate positive drainage, like low-slope roofs. When correctly installed, tapered insulation helps eliminate problems due to ponding water and can extend the longevity of your low-slope roofing system.