Polystyrene Thermoplastic

Polystyrene is a waterproof thermoplastic foam which is an excellent sound and temperature insulation material. It comes in two types, expanded (EPS) and extruded (XEPS) also known as Styrofoam. The two types differ in performance ratings and cost. The costlier XEPS has an R-value of R-5.5 while EPS is R-4. Polystyrene insulation has a uniquely smooth surface which no other type of insulation possesses.

Typically, the foam is created or cut into blocks, ideal for wall insulation. The foam is flammable and needs to be coated in a fireproofing chemical called Hexabromocyclododecane (HBCD). HBCD has been brought under fire recently for health and environmental risks associated with its use.