Black Polythene Heavy Gauge/ DPM

Damp Proof Membrane, a waterproof sheet (like thick polythene) laid under concrete floors or over foundations to stop ground moisture from rising into a building, preventing dampness, mold, and structural damage, unlike a DPC (Damp Proof Course), which stops rising damp in walls. DPMs protect flooring, improve energy efficiency, and extend a building's lifespan by creating a crucial moisture barrier.