Damp Proof Membrane

What is a Damp Proof Membrane?

A damp proof membrane, or DPM, refers to any sheet of waterproofing material that is used to prevent moisture from entering a building structure. Most commonly, a DPM is a large sheet of damp proofing that lies underneath the solid floor of a structure. By being welded at the joints and then welded to the DPC of the building, a continuous seal is created, completely separating the building from the damp ground beneath it. Modern building standards require a DPM/DPC to be fitted at the time of construction. However, this hasn’t always been the case and older properties may not be completely sealed. When laying a DPM under a solid floor slab it is important to bed it into soft sand. This is to prevent the sharp edges of concrete or hardcore damaging the sheet and compromising its effectiveness.

damp-proof-membrane-1200g.jpgDamp proof membranes are made from a variety of materials. Most commonly they consist of heavy gauge plastics, such as high density polyethylene (HDPE), pitch coated polymers or in liquid form with damp proof injection. Other applications of damp proof membranes include damp proofing walls, the conversion of outbuildings, cellar and basement conversions and the remediation of damp proofing problems. DPMs may be fitted in new builds or retrofitted.

Membrane-roll-on-floor.jpgDamp proof membranes may also be used within cavity walls to prevent lateral movement of water into a structure (penetrating damp). These systems are known as cavity drain membranes and may be fitted at the time of construction, or retroactively as a remedial measure to penetrating damp problems, and are an alternative to cementitious tanking. A cavity drain membrane consists of a DPM fitted within the cavity wall, allowing moisture to penetrate the outer skin of a building but then trapping it with the DPM in the cavity gap and diverting it to a suitable drainage point.

There is a huge range of damp proofing products available on the market, each intended to meet a variety of specific requirements. Many modern damp proof membranes come as an entire ‘system’ with specially designed fixings and fittings to create a complete and impenetrable unit. Triton are the market leaders of damp proofing membranes providing a comprehensive range for all situations.




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