Polythene DPC (Damp Proof Course) is a flexible, heavy-duty polyethylene membrane designed to prevent moisture from rising through walls from the ground up, protecting buildings from dampness, rot, and structural decay.

• Preventing Rising Damp: Installed horizontally within brick, block, or stone masonry walls to act as an impermeable moisture barrier between the ground and the upper structure.

• Cavity Tray Systems: Used above window and door openings or at roof abutments to bridge cavities and catch or redirect moisture away from interior walls.

• Thresholds & Door Openings: Placed beneath exterior door sills and thresholds to stop groundwater from seeping into the building's interior.

• Ground Floor Protection: Forms a continuous damp-proof barrier around the perimeter of a building, integrating with the damp-proof membrane (DPM) in the floor slab.

• Timber Protection: Shields embedded timber plates, joists, and structural elements from direct contact with wet masonry or sub-surface moisture.

Available for collection from our Rugby branch or local delivery using our own fleet.

Delivery is kerbside and the final offloading position is always subject to safe access and the driver’s discretion.

Please tell us before delivery about:

• Narrow roads or restricted entrances
• Parked vehicles or limited turning space
• Overhead cables, trees or other obstructions
• Soft, sloping or unsuitable ground
• Any other access concerns

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What is a Damp Proof Course (DPC) and why is it needed?

A DPC is a waterproof barrier built or laid horizontally into masonry walls. It stops moisture from the ground from traveling upward through the bricks via capillary action (known as rising damp), which can otherwise cause peeling wallpaper, rotting timber, and damp patches inside your home.

How high above ground level should a DPC be installed?

According to building regulations, a horizontal DPC must be installed at least 150mm above the external ground level to prevent splashing rain or external paving from bridging the damp barrier.

Is Polythene DPC compliant with building standards?

Yes. High-quality polythene DPCs are manufactured to meet British Standards (such as BS 6515) and are approved for use in standard masonry walls. Always look for a DPC marked with BBA (British Board of Agrément) certification to ensure it meets regulations.

How do you join or overlap polythene DPC rolls?

When joining two pieces of DPC, they should be overlapped by at least 100mm (4 inches) and sealed with a compatible DPC lap tape or jointing adhesive to ensure moisture cannot seep through the join.

Can polythene DPC be used under timber wall plates?

Yes. Polythene DPC is commonly laid underneath timber wall plates (the timber resting on top of brickwork) to prevent moisture from transferring from the masonry into the wood, protecting it from rot and decay.

What is the difference between a DPC and a DPM?

• DPC (Damp Proof Course): Specifically designed to sit within vertical or horizontal masonry walls to stop rising damp.

• DPM (Damp Proof Membrane): A thicker sheet membrane laid horizontally across the entire floor slab or sub-base to prevent moisture from rising through solid concrete ground floors.