Damp Proofing Dulwich

Dulwich covers Dulwich Village, West Dulwich, East Dulwich and the streets towards Herne Hill, with Sydenham Hill and Dulwich Wood rising to the south. Almost the whole area sits on London Clay, which drains slowly and holds water in the ground long after rain. That, and the age of the houses, explains most of the damp we find in SE21 and SE22.

The River Effra rose on the slopes around Norwood and ran north through Dulwich and Herne Hill towards Brixton. It now runs in culverts, but the shallow valley it followed is still there, and streets along its old course collect surface water and groundwater after heavy rain. Spring water from Sydenham Hill also feeds down the slopes into the southern part of the area.

The housing is varied. Dulwich Village has Georgian and early Victorian houses, many of them listed. East Dulwich, around Lordship Lane, is mostly late Victorian terraces, many converted into flats. West Dulwich and the streets towards Sydenham Hill have large Edwardian and interwar family houses. Each type has its own damp problems.

In the Victorian terraces of East Dulwich and Herne Hill, rising damp is very common. The original slate or bitumen damp proof course often cracks or is bridged by raised front paths and rendered plinths. The signs are tide marks, salt staining and crumbling plaster along the bottom of ground floor walls.

Penetrating damp is just as frequent. Bay roofs, parapet walls, valley gutters and chimney stacks let rain into solid brick walls when flashings fail. Many Dulwich houses also have decorative render and tiled porches that trap water once they crack. We trace each leak with moisture readings and thermal imaging before recommending a repair.

In the older houses of Dulwich Village, walls are often built with soft bricks and lime mortar. These walls need to breathe, and cement renders or plastic paints applied in the past can trap moisture inside them. We use breathable lime based treatments where they suit the building, and we flag anything that may need listed building consent.

Under the floors, most Dulwich houses have suspended timber floors that rely on air bricks. Extensions, raised patios and blocked vents cut off that airflow, and damp joists and wet rot can develop unseen. Many larger houses also have cellars, which take on water from the surrounding clay and are increasingly being converted.

Condensation and black mould are the most common problems in East Dulwich flats, where large houses have been split into smaller homes with kitchens and bathrooms in rooms never designed for them. Better ventilation and extraction usually solve the problem, and we measure the walls first to rule out other causes.

Many of our Dulwich surveys are for buyers. Mortgage valuations often flag damp from a quick meter reading, and those meters give high readings on walls with salts or condensation even when there is no rising damp. A proper damp survey separates real damp from false readings, so you know what you are buying and whether any work is needed before you exchange.

Much of Dulwich is owned by the Dulwich Estate, which manages a Scheme of Management requiring its consent for many external alterations, on top of planning permission from Southwark Council. Internal damp treatments are usually simpler. Every survey is carried out by a CSSW and CSRT trained specialist, and you receive a written report with photos, the cause and the recommended fix. We can usually survey Dulwich homes within a few working days.