Damp Proofing Chiswick

Chiswick is one of West London's most attractive residential areas, and its housing stock is almost entirely Victorian and Edwardian. The terraces around Turnham Green, Grove Park and the streets either side of Chiswick High Road were built between the 1870s and the First World War, while Bedford Park, often described as the first garden suburb, is a conservation area of red brick Queen Anne revival houses. Further west and south you find interwar semis, mansion blocks and a growing number of newer flats along the river.

Most of these older homes have solid nine inch brick walls, lime based mortars and suspended timber ground floors. That combination behaves very differently from a modern cavity wall house, and it explains most of the damp we see in W4. The most common fault is a bridged damp proof course, where a garden path, patio or flower bed has been built up against the wall over the years, or where a rendered plinth runs down below ground level. Water then bypasses the original slate or bitumen damp proof course and soaks into the bottom of the wall.

The second big issue is ventilation under the floor. Chiswick's Victorian houses rely on air bricks to keep the void under the floorboards dry, and when those air bricks are blocked by raised ground, extensions or later rendering, moisture builds up and joists and wall plates start to rot. We regularly find wet rot, and occasionally dry rot, in front bay floors and under hallways where the problem has been going on unnoticed for years.

Penetrating damp is also common, particularly on exposed gable ends, around bay windows and through chimney breasts where flashings and pots have failed. In the flats above shops along the High Road and in converted houses, condensation and black mould are the most frequent call outs, and these are often misdiagnosed as rising damp.

The river adds another layer. Properties around Strand on the Green, Grove Park and the streets nearest the Thames sit on a higher water table, and cellars and lower ground floors here can be damp all year and take on water during very wet winters. These spaces need a properly designed below ground solution, usually a cavity drain membrane with a sump and pump, rather than a coat of tanking slurry.

Because so much of Chiswick sits within conservation areas, and because period fabric needs to breathe, we always survey before recommending anything. Where the cause is a bridged damp proof course or a blocked air brick, fixing that cause is often all that is needed. Where treatment is required, we use breathable, lime compatible plasters on solid walls and reserve chemical damp proof courses for walls where the survey shows genuine rising damp.

Buyers are another big part of our work in Chiswick. Period houses here change hands regularly, and mortgage valuers frequently flag damp or timber issues that need a specialist report before the sale can go ahead. Our pre-purchase damp and timber surveys look at the whole property, explain what is genuinely a problem and what is simply the normal behaviour of an old solid walled house, and give a clear scope of any work required. That helps buyers negotiate on the facts rather than on a generic recommendation to inject every wall.