Polymer-modified bitumenPMB

A sheet waterproofing material comprising a polyester or glass fibre carrier coated with oxidised or polymer-modified bitumen, normally installed in two or more bonded layers on flat roofs. It is the modern UK term for what was traditionally called built-up felt roofing.

A reinforced bitumen membrane applied by melting the underside of the sheet with a gas torch so that it bonds to the substrate or preceding layer as it is rolled out. Torch application requires strict hot-works controls, and flame-free alternatives such as self-adhesive membranes are often specified where fire risk must be eliminated.

A dense, voidless waterproofing material composed of graded limestone aggregate bound with bitumen, heated and applied in molten form by hand float to roofs, balconies, tanking and flooring. It sets to a seamless surface and has a long history of use in UK construction.