Bitumen waterproofing sheets consist of a reinforcement, which is coated on both sides with bitumen. Bitumen is produced by distillation of crude oil and refined by the incorporation of plastics to "polymer bitumen". Thus, in the modification with SBS polymers elastomer bitumen is produced – in contrast with APP polymers plastomer bitumen is created.
- Elastomer bitumen is highly elastic ("rubbery") and thereby remains flexible even at low temperatures.
- Plastomer is highly thermoplastic ("soft") and thereby remains stable even at high temperatures.
Both bituminous mixtures aging for decades and are environmentally safe, both in production and in use.
Bitumen sheets in the flat roof sealing are at least laid in two layers, the individual layers are full-faced welded.
Bitumen sheets in pitched roofs are used as top sealing layer (classical roofing) and in the sub-roofs.