There are several materials and methods used for flat roofing. Some popular types include: Built-Up Roof (BUR): This is the traditional hot tar and gravel roof. Modified Bitumen: A single-ply roll roof with a mineral-based wear surface. EPDM: A durable rubber material that resembles an inner tube but is engineered to resist damage from sunlight. TPO & PVC: Single-ply roofing systems that are heat-welded during installation.