Damp proof Membrane(DPM). It comes in a roll of1 Meter height by 72 Meters length. The general appearance is a roll of  black polythene. A damp-proof membrane (DPM) is a membrane material applied to prevent moisture transmission. A common example is polyethylene sheeting laid under a concrete slab to prevent the concrete from gaining moisture through capillary action. It can also be used as a protective cover when doing house painting to prevent the paint from staining the floor.