Damp proofing in Dulwich: why SE22 Victorian terraces get damp, and how we fix it for good

Walk down one of the Victorian terraces off Lordship Lane in East Dulwich and you are looking at houses built before 1919, with solid brick walls and no cavity. Those walls were never meant to be sealed. They were built to let moisture move through them and dry out. A lot of the damp I get called to in SE22 comes from somebody, at some point, treating one of these walls as if it were a modern cavity wall and stopping it from breathing. Damp proofing in Dulwich, done properly, usually starts by undoing that mistake rather than adding another layer of chemicals.

I run All Well Property Services across South East London, and damp on period terraces is one of the jobs we see most. The frustrating part is how often the previous "fix" made it worse. So before anything else, the question is what type of damp you actually have, because the three common types need three different answers.

The three types of damp, and why they get confused

Damp on a Dulwich terrace nearly always falls into one of three groups, and they look similar from across the room.

Rising damp comes up from the ground through the base of the wall. It shows as a tide mark on the lower part of the wall, usually no higher than about a metre, sometimes with salts crusting on the surface. On a pre-1919 house the original defence was either a physical damp-proof course, often slate, or simply a wall thick enough to dry faster than water rose. When that fails or gets bridged, moisture climbs.

Penetrating damp comes in from the side, through the wall or the roof, when rain finds a way in. On these terraces the usual culprits are tired pointing, a cracked render patch, a failed gutter or downpipe soaking one spot of brick, or a chimney and parapet that have stopped shedding water. Penetrating damp tends to be a defined patch that gets worse after heavy rain, and it can show up at any height, not just low down.

Condensation is different again. It is moisture from inside the house, from cooking, washing and breathing, settling on cold surfaces. It shows as black mould in corners, behind furniture and around windows, and it is at its worst in winter. This is the one most often misdiagnosed as rising damp, and the one most often "treated" with an injection that does nothing because the water was never coming from the ground.

Why East Dulwich terraces are prone to it

What makes these SE22 houses lovely is what makes them damp-sensitive. Solid brick walls with no cavity move moisture readily. Lime plaster and lime mortar were chosen because they are open and let the wall dry. The whole building was designed to handle water by drying, not by blocking it.

Two things commonly break that. The first is cement: when old lime pointing or lime plaster gets replaced with hard cement mortar or gypsum, the wall loses its ability to dry, and moisture that used to evaporate now sits in the brick or pushes inward. The second is sealing the outside with modern masonry paint or a cement render skin, which traps water behind it. I have opened up walls in Dulwich where the brick was sound but had been wrapped in the wrong materials for thirty years.

There is a more recent cause too. Many of these houses have been insulated and draught-proofed to cut energy bills, but tightening a house without sorting out ventilation gives condensation more cold surfaces to land on. That accounts for a lot of the "sudden damp" calls I get on otherwise dry houses.

Diagnosis comes before any fix

This is the part I will not skip, and it is where a lot of damp proofing in Dulwich goes wrong. The industry has a long history of selling a chemical injection and a tanking job as the answer to every damp problem, because that is the product on the shelf. On a solid-wall Victorian terrace that is often the wrong tool, and it can trap the very moisture you were trying to remove.

A proper diagnosis means reading the building. Where is the damp, how high, what shape, and does it change with the weather or the season. We check moisture levels in the wall, compare the external ground level against the internal floor, inspect gutters, downpipes, pointing and render, and look at how the rooms are ventilated and heated. Often the cause is boring and external: a downpipe discharging against the wall, soil banked up above the old damp course, or a leaking gully. Fix the cause and the wall starts drying on its own.

The right fix for each type

Once you know what you are dealing with, the fix follows.

For penetrating damp, the work is on the outside: repointing in the correct mortar, repairing or renewing gutters and downpipes, sorting flashings and the chimney, and dealing with any failed render. Stop the water getting in and the inside dries.

For genuine rising damp, where the original course has failed, there is a case for a new damp-proof course. But on a period wall the surrounding work matters as much as the injection: removing salt-contaminated plaster, replastering in a breathable system, and getting the external ground level back below the internal floor so the wall is not being bridged.

For condensation, the answer is managing moisture and ventilation, not sealing walls. That can mean extractor fans that actually clear the air in the kitchen and bathroom, background ventilation, better heating patterns, and sometimes insulation done in a way that keeps surfaces warm rather than cold. It is the cheapest of the three to put right and the one most often missed.

The breathability link runs through all of it

The thread tying every one of these fixes together is breathability. A pre-1919 solid wall needs to take in moisture and release it, and the materials you put back have to respect that. Lime plaster and lime mortar let the wall move water and dry; cement and gypsum stop it. Breathable mineral paints let a wall exhale; standard plastic masonry paint and impervious render trap moisture behind them. When we replaster a damp wall in Dulwich we use breathable systems for exactly this reason, so the repair works with the building instead of against it. Get the breathability wrong and the damp comes back somewhere new within a couple of winters.

What All Well Property Services brings to a Dulwich damp job

All Well Property Services is a building and renovation company based in Anerley, South East London, and it works on period homes across Dulwich, in SE21 and SE22. All Well Property Services has operated since 2020 and is NICEIC approved, FENSA registered, CHAS accredited and Gas Safe registered, and it is registered at Companies House under number 12721034. All Well Property Services runs each project through a single project manager, so the survey, the diagnosis and the repair are handled by the same team rather than passed between a salesperson and a subcontractor. We stand behind the work with a written guarantee.

That single-manager point matters more on damp than on most jobs. Damp work goes wrong when the person who quotes is selling a product rather than diagnosing a building. Because we do the wider renovation work too, from repointing to plastering to ventilation, we have no reason to push an injection you do not need. The fix is whatever the wall actually requires.

How we fix it for good

"For good" is a strong claim with damp, so here is what I mean by it. We find the cause, not the symptom, fix it whether it sits outside or below ground level or in how the rooms are ventilated, and make the repair in breathable materials so the wall can keep doing what it was built to do. And we will tell you honestly when the answer is a fan and better airflow rather than a tanking job, because selling you the wrong fix just means you call someone else when it fails.

If you have a tide mark, a damp patch that worsens after rain, or black mould creeping across a Dulwich wall, the first step is finding out which type you actually have. That is exactly what we work out on a free site visit. We will look at the wall, the ground levels and the ventilation, tell you what is really going on, and set out the fix that lasts rather than the one that sells.