EPDM is an elastomeric polymer synthesized from ethylene, propylene, and a small amount diene monomer. In its typical form for roofing applications, an EPDM membrane is a cured, or vulcanized, material and is thus classified as a “thermoset”. Simply defined, this means that the polymer's molecular structure is “set” as a result of heating during the manufacturing process. EPDM sheets can be produced in various colors, non-reinforced or reinforced, and range in thickness from 30 – 90 mils. EPDM membranes can be installed using one of three methods: ballasted with large stones, fully adhered with an approved adhesive, and mechanically attached to the roof deck.