Black Polythene DPC Membrane 30m Roll

Black polythene DPC membrane is one of those products that has been used on building sites for decades, and for good reason. It does the job, it is simple to install, and it lasts. This DPC polythene roll provides a continuous moisture barrier within masonry walls, preventing ground moisture from rising through the wall structure and causing damp problems in the building above. As a damp proof course membrane, it is suitable for both new build and remedial applications wherever a reliable horizontal moisture barrier is needed in brickwork or blockwork construction.

Each roll is 30 metres long and is available in a wide range of widths: 100mm, 112.5mm, 150mm, 225mm, 300mm, 337.5mm, 450mm, 600mm and 900mm. This means you can match the DPC width to the wall thickness you are working with, whether that is a standard 100mm internal skin, a 225mm solid brick wall, or anything in between. Getting the right width matters. A DPC that is too narrow leaves the wall edges exposed, and a DPC that flaps around in the wind during a mortar bed set is nobody’s idea of fun.

Where Black Polythene DPC Membrane Is Used

Black polythene is the standard choice for horizontal DPC installation in cavity walls, solid walls, and separating walls. The polythene construction is resistant to the alkaline environment of fresh mortar, which is what makes it suitable for being bedded directly into mortar courses during construction. It will not react with the surrounding materials and does not need any priming or preparation of the polythene itself before laying.

The black colour is useful on site too. It is easy to see that the DPC is correctly positioned before the next course of masonry goes on top, which helps with quality checks during construction. White or translucent membranes can be harder to spot once they are partially covered. Small detail, but worth noting when you are working quickly.

Choosing the Right Roll Width

As a general rule, the DPC width should match or very slightly exceed the wall width it is covering. For a standard 100mm blockwork skin, use the 100mm roll. For a 225mm solid brick wall, use the 225mm roll. For cavity wall construction where the DPC needs to run across the full cavity and both leaves, measure the total bearing width and select accordingly. The 30m roll length is practical for most projects without leaving excessive waste, and buying in quantity reduces the cost per metre significantly on larger jobs.

This damp proof course membrane is supplied in roll form, making it easy to transport and store on site. It can be cut cleanly with a Stanley knife or scissors, and joints should be lapped by a minimum of 100mm in the direction of the wall run to maintain continuity of the moisture barrier throughout the structure.