Betagum is an asphalt sheet -5 ° C with a tile whose asphalt mixture consists of refinery asphalt and thermoplastic polymers. It has non-woven polyester or glass fiber as reinforcement and mineral tile as an upper coating. Alternatively, quartz sand or polyethylene film may be used. The bottom surface is covered with polyethylene film suitable for use with a flame. A 10cm wide margin is left free of tile to create the joint with the adjacent sheet. This area is covered by a special plastic film which prevents the roll from sticking together, while it melts easily with a flame.