PETRAGUM waterproofing membrane 3 or 4 mm thick is a high-performing membrane. PETRAGUM membranes are manufactured from bitumen, modified with atactic polypropylene (APP).

The compound is a mixture of distilled bitumen, thermoplastic polymers and elastoplastic copolymer which gives the membrane excellent durability and flexibility at low temperatures, and the ability to withstand high temperatures. The reinforcement is of 150 g/sqm nonwoven polyester fabric to give the needed elongation and to provide the membrane with the required resistance to heat aging, puncture, and rotting.

PETRAGUM is manufactured with polyethylene film on the lower face to prevent sticking in the roll and which melts quickly when subject to heat during the application, which gives a visual sign of the correct melting temperature of the membrane.  The upper face is covered with fine sand, granules, or colored slates when the membrane is used as the exposed top layer.