Early damp proof courses

The wall below ground level is likely to be permanently damp and, to prevent moisture rising through capillary action, it is, nowadays, a requirement of the Building Regulations that walls should resist the passage of moisture. This requirement is most commonly complied with through the provision of a damp proof course (DPC). DPCs first came into use towards the end of the Victorian period when materials such as tar and sand, or hessian soaked in tar were commonly used. On more prestigious buildings, lead and copper were often employed. It was also common to find buildings with two or three courses of engineering bricks or layers of slate providing a barrier to rising damp. The DPC should be well clear of the ground (at least 150mm) and should ideally be a flexible material to allow for slight differential movement. Slate DPCs often failed due to cracking as the building settled slightly during its life.

In practice, many early DPCs are no longer effective; materials become brittle with age, buildings settle, and external levels often change due to such measures as the resurfacing of footpaths and the like. Fortunately, many buildings can cope adequately without a DPC as long as the brickwork is of the right quality and the ground is well drained.