The bituminous vapour membranes in the DS-PP range are produced using a bitumen mixture and have a polypropylene non-woven fabric on both sides. They have a dual purpose and can be used as a vapour barrier in roofs by laying them underneath the insulation or as an undertile impermeable membrane on top of a ventilated planking. The range offers eight different versions that differ from one another in terms of their areal mass and tensile strength.