A damp-proof course is a continuous barrier in a wall that prevents moisture rising from the ground. It’s typically made from water-resistant materials like bitumen or plastic. It’s crucial in maintaining the structural integrity and stability of the wall.

Building regulations state that walls must resist the passage of water from the ground. Almost all modern houses in the UK will be built with some form of damp-proof course to control dampness.

Key features

• Continuous and unbroken

• Resistant to water and moisture

• Appropriate thickness (should be thick enough that it provides an effective barrier but not so thick that it affects structural integrity)

Different types

• Horizonal damp-proof course

Most common and is installed at the wall’s base to prevent rising of dampness. Typically made from bitumen, plastic or slate.

• Vertical damp-proof course

Is installed in the walls of a building to prevent moisture from entering through the walls. It is installed regularly in the brickwork and is made of lead or copper.

• Cavity damp-proof course

Is installed in the cavity wall, serving as a barrier between the inner and outer leaves of the wall. Typically made from flexible materials such as polyethene or polypropylene.

• Chemical damp-proof course

Created by injecting a chemical into the wall, the injected chemical seeps into the brickwork and prevents moisture from rising. Used when it’s not practical to install a physical damp-proof course (for example, in older buildings or when the existing damp-proof course needs replacing)

• Electro-osmotic damp-proof course

Uses electrical currents to repel moisture and prevent rising damp. This is used when physical or chemical damp-proof course is not practical or effective.