Ethylene Propylene Diene Monomer, better known as EPDM, is a common roofing material in the construction and building industry. In low slope roofing applications, EPDM is considered one of the three thermoset types of flexible single ply sheet materials. Chlorosulfonated Polyethylene (CSPE) and Polyisobutylene (PIB) are the other two types of roofing in the thermoset category.