Thermoset single-ply membranes, such as ethylene propylene diene monomer (EPDM), are synthetic rubber materials that are cured or vulcanized during manufacture. Thermoset polymers can only be bonded to like material with glue or adhesive seam tape. EPDM sheets used for roofing became widely available here in the early 1980’s. They are usually black in color and range in thickness from 45 mils to 120 mils. The most common thicknesses of EPDM single-ply roof membrane materials are 45 mils and 60 mils. EPDM installations may be ballasted, mechanically attached or fully adhered to approved substrates.