Bare bitumen sheets with/without metal strips consist of raw felt cardboard soaked in bitumen. The cardboard is merely the carrier material for the bitumen mass that acts as a seal. The bitumen membranes can be glued to the surface to be sealed using various processes. Finally, the waterproofing must be provided with a top coat. The waterproofing can be supplemented by the insertion of metal strips, which must always be installed as a second layer from the water-attacking side. As a result, the required minimum injection can be omitted, the water vapour tightness is significantly increased and the sealing can be loaded with significantly higher pressure. Copper and stainless steel are available as materials for the metal straps.
Source: bauwion
