Welcome to the default, or old school, material for flat roof installations. It’s technical name: Ethylene Propylene Diene Monomer is a mouthful. While it is simply a rubber material, we’ll go with EPDM since everyone else does.
EPDM rubber roofs compete directly with TPO and PVC single-ply membranes as a low-slope roofing material. EPDM, though, tends to only be used on flat roofs while PVC and TPO are sometimes used on sloped roofs.