Polyisocyanurate (Polyiso) is a closed-cell, rigid foam board insulation consisting of a foam core sandwiched between two facers. The foam core is composed of closed-cell rigid Polyiso foam produced through the chemical reaction of an “A” side (MDI) and a “B” side (polyester polyol with various additives such as catalysts, surfactants, and flame retardant) plus a blowing agent (pentane). For roofing applications, the most common facer is a glass-reinforced fiber (GRF) material made from over 90% recycled post-consumer and post-industrial fiber.

The major raw materials at a Polyiso insulation manufacturing plant consist of chemical liquids stored in tanks onsite. The chemicals for the “A” side (MDI), the “B” side (polyester polyol plus catalysts, surfactants, and flame retardants) and the blowing agent (pentane) are pumped from storage into process tanks. The “B” side and blowing agent are then pumped to a mixer and then to a mix head where they are combined with the “A” side and injected between the top and bottom facers on the pour table. These chemicals combine on the pour table and react rapidly to form a closed-cell foam board that is sandwiched between the top and bottom facers. The rigid foam board then travels within a heated laminator on moving conveyor belts, which aids in cell formation and hardens the board. The board then exits the laminator and is fed through saws that trim the board to the desired width and then through a crosscut saw that cuts the board into desired lengths. The finished rigid boards are then stacked, packaged with plastic wrap,labeled, and moved via fork truck to a warehouse area for storage and eventual loading onto trucks for shipment.