A damp proof membrane is a continuous sheet installed beneath floors to stop ground moisture travelling upward, while a damp proof course is typically placed within masonry walls to prevent rising damp moving through brickwork.
Preventing Rising Damp and Water Ingress in Floors and Walls FAQs
Damp proofing products help control moisture movement within buildings, protecting walls, floors and structural materials from water ingress and condensation related damage. The range typically includes damp proof membranes, damp proof courses (DPC), liquid waterproof coatings, tanking systems and protective additives used during construction or refurbishment. These products are commonly applied in ground floor installations, basements, extensions and renovation projects where moisture protection is required to maintain structural integrity and prevent internal finishes from deteriorating. They are often installed alongside Concrete & Mortars during subfloor preparation to create a continuous moisture barrier beneath screeds and floor coverings.
Many damp proofing solutions are designed to integrate with wider building systems, helping to manage moisture at different stages of construction. Sheet membranes and cavity drainage systems are used behind wall linings and below flooring, while liquid applied coatings form seamless barriers around foundations and retaining walls. When combined with Insulation, damp proof layers help reduce condensation risk within wall and floor build-ups, supporting thermal efficiency as well as moisture control. In refurbishment settings, chemical damp proof courses are injected into masonry to interrupt rising damp, allowing replastering work using compatible materials from Plaster & Plasterboard ranges once walls have dried.
Materials used within this category typically include polyethylene membranes and bitumen based coatings. Products often comply with recognised guidance such as BS 8102 for protection of below ground structures against water ingress, and many are suitable for use with ventilation strategies that reduce trapped moisture within enclosed spaces. Installation usually involves clean, prepared substrates and careful sealing around joints, service penetrations and edges, frequently supported by tapes, sealants or accessories found within Sealants & Adhesives. By limiting moisture penetration, damp proofing systems help extend the lifespan of finishes, improve internal conditions and reduce maintenance caused by mould, staining or material breakdown.
Damp Proofing FAQ's
Yes, chemical injection creams and liquid coatings can be used in retrofit situations. Holes are drilled into mortar joints and filled with a damp proofing solution that forms a water-repellent barrier inside the wall.
Most cementitious tanking products require a clean, bare and sound substrate to bond correctly. Existing paint, loose coatings or contaminated surfaces should be removed before application, as these can prevent adhesion and reduce the effectiveness of the waterproof barrier.
Drying time depends on wall thickness, moisture levels and ventilation, but walls often require several weeks or longer. Using breathable plaster systems compatible with damp proof treatments helps avoid trapping moisture.
Membranes should be overlapped according to manufacturer guidance, typically by at least 100–150mm, and sealed using compatible jointing tape or waterproof sealant. All laps, corners and service penetrations must be fully sealed to prevent moisture tracking between layers.