Abstract: An improved method of adhering a waterproofing membrane to an underlayment and substrate is disclosed. A perforated underlayment comprising a tough, fibrous reinforcing base layer or matting impregnated with a bitumen/polymer mixture substantially similar to the bitumen/polymer mixture of the waterproofing membrane is placed on a substrate. The exposed underside of the waterproofing membrane is heated until it reaches a softening point. Thereafter, the membrane is unrolled onto the underlayment whereby the membrane and the underlayment are bonded essentially into a single ply. Additionally, when the membrane is unrolled, the bitumen/polymer mixture is sufficiently molten to flow and pass through the openings of the perforations thereby bonding the final waterproofing membrane to the substrate.

Abstract: A method of producing waterproofing membranes is disclosed. A tough, fibrous web or matting is saturated with a thermoplastic waterproofing compound to produce a predetermined minimum thickness on both the upper and lower surfaces of the membrane sufficient to provide adequate flow characteristics during installation of the membrane without excessive exposure of the support matting to deteriorating conditions during installation. Afterwards the coated membrane is cooled and inverted for further treating at least one of the exposed surfaces with additional material.