PVC membrane

A factory-manufactured polymeric waterproofing sheet, typically EPDM, TPO or PVC, installed in a single layer and joined at laps by welding, adhesive or tape. Single-ply systems may be mechanically fastened, fully adhered or ballasted, and are widely used on flat and low-pitched roofs.

Thermoplastic polyolefin, a polymer blend based on polypropylene and ethylene propylene rubber, used as a heat-weldable single-ply roofing membrane. Being thermoplastic, seams are joined by hot-air welding rather than adhesive, and the material contains no plasticisers. Related grades are used for automotive interior and exterior components.

Ethylene propylene diene monomer (M class) rubber, a synthetic elastomer with excellent resistance to ultraviolet light, ozone and weathering. In roofing it is used as a single-ply waterproofing membrane, often supplied in large prefabricated sheets, and it is also widely used for seals, gaskets, hoses and glazing profiles in the automotive, marine and industrial sectors.

The overlap between adjacent sheets of roofing membrane or underlay where they are joined and sealed, by heat welding, solvent welding, adhesive, tape or bitumen bonding depending on the material. Lap integrity determines the watertightness of sheet systems, so minimum lap widths and the staggering of end laps are specified in system guidance.