Damp, Mould and the Old Solid Walls Our Housing Still Relies On
Submitted by Andy_B on Thursday, 01 October 2026 Page Views: 9
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Britain's homes are, on the whole, old. Alongside the modern estates and new blocks of flats, a great many people still live in buildings put up long before cavity walls, damp proof courses or central heating were normal. Some of those buildings are owned by social landlords. Historic almshouses still run by charities, converted schools and chapels, and long streets of Victorian terraces now managed by housing associations all house tenants today.These buildings were well made for their time. The trouble is that they were designed to work in a very particular way, and a century of changes has often worked against them. When damp and mould appear, old walls can be the hardest part of the housing stock to put right.
How old solid walls were meant to work
Most homes built before the early twentieth century have solid walls of brick or stone, laid in lime mortar and finished inside with lime plaster. These materials are soft and porous. Rain soaks a little way into the outer face, and moisture from inside the home soaks into the plaster, but neither stays for long. Because lime lets moisture move through it, the wall can dry out again in both directions.The rest of the house helped. Open fires pulled air up the chimney and drew fresh air in through gaps around doors and sash windows. Rooms were draughty, but the constant flow of air carried damp away. The whole building behaved a little like a coat that lets you sweat without getting soaked.
What changed over the last century
Over the years, many of these homes were updated with materials that do not behave like lime. Cement render and hard cement pointing went on the outside. Gypsum plaster and plastic paints went on the inside. Chimneys were blocked up, sealed windows replaced old sashes, and garden or pavement levels crept up against the base of the walls.Each change made sense on its own, but together they turned a building that breathed into one that holds water. Moisture still gets into the wall, but it can no longer get out easily. At the same time, modern life adds more moisture indoors. We shower daily, cook with lids off, and often dry washing on radiators. If heating is kept low to save money, cold walls meet damp air, condensation forms, and mould follows.
Awaab's Law and the pressure on landlords
In December 2020, a two year old boy called Awaab Ishak died in Rochdale after long exposure to mould in his family's housing association flat. His death led to Awaab's Law, which sets firm time limits for social landlords in England to investigate and fix damp and mould hazards once they are reported. Many housing teams have responded by booking awaabs training for their officers, so they understand both the legal duties and the building science behind damp and mould.That second part is a real challenge in older buildings. The quick fixes that seem to work in a modern flat, such as waterproof paint, a cement based render or sealing up every gap, can make an old solid wall wetter over time. Staff who inspect a home and decide what to do next need to understand why the damp is there, not just how to cover it up.
A surveyor who knows the difference between condensation, rain getting in through the wall and moisture rising from the ground will reach a better answer, and reach it faster. In a historic building that difference matters even more, because the wrong treatment can damage fabric that has lasted for well over a hundred years.
What good practice looks like in an older home
The first step is always to find the source. In older buildings the cause is often simple and outside. Blocked gutters, cracked downpipes, failed pointing, leaking roofs and soil piled against the wall all send water where it should not go. Fixing these basic faults is cheaper than any treatment and often solves the problem on its own.The second step is to choose materials that suit the building. Where cement render or gypsum plaster is trapping moisture, conservation specialists often recommend replacing it with lime. Where paint is sealing a wall, a breathable paint may help it dry. For listed buildings, the local conservation officer should be involved before work starts.
The third step is air. Old homes need a steady supply of fresh air to replace the draughts that were lost. Extractor fans in kitchens and bathrooms, trickle vents and simple habits like opening a window after a shower all help. In a listed building, fans and vents need care so they do not harm historic features.
Finally, good practice means talking to residents. Many tenants already know when and where the mould appears. Their knowledge, combined with a careful survey, gives the clearest picture. Advice on heating and ventilation should be practical and kind, never a way of blaming the household for a problem the building itself is causing.
Good records help as well. Noting when a report came in, what was found, what was done and whether it worked builds up a history for each home. In an old building that history is especially useful, because damp often follows the seasons. A wall that looks dry in August may be wet again by January, and a follow up visit in the colder months is the only way to know whether a repair has really worked.
Old walls, new duties
Historic buildings in social use are part of our shared heritage, and the people living in them deserve a safe, healthy home. Those two aims do not have to clash. When landlords understand how solid walls were meant to work, and put right the changes that stopped them working, damp and mould can often be dealt with for good.Awaab's Law has raised the stakes. The best response is not a rush of sealants and quick cover ups, but better knowledge, careful surveys and repairs that respect the way old buildings breathe.
With many thanks to Denisbin for the Creative Commons photo at top.
