Damp is a particular problem with old houses, especially ones that may have been neglected for a time. And it is at this time of year – the winter – when the weather is wet and cold that people start to feel the negative impact of damp. A damp house tends to always feel cold, is much more difficult to heat and in the worse cases can smell mouldy. There is a lot of misunderstanding around what causes damp and how it can be remedied and in most instances there is usually a simple answer.

Here are some typical causes of damp in old houses and how to beat them:

High ground levels

If the ground against the outside of an older house is as high or higher than the floor inside then this will almost certainly cause a damp problem. Typically, houses were built on raised ground but over time earth can be banked up against external walls, or years of building work – where paths and patios have been laid – can result in the damp proof course being bridged. You can see this when you visit an old house and you step down onto the floor as you enter. If earth has banked up this will have to be dug away. Likewise, climbing plants and hedges butting up against walls should be cut back. Installing a shallow trench filled with gravel around the external wall of a home is good way to allow moisture to escape.

Incompatible renders and paints

Many older houses were designed to prevent damp problems by being built using permeable materials.  Little waterproofing was used but moisture and condensation could escape by passing through the walls, floors and ceilings. This means damp can become an issue if unsuitable building work has been carried out over the years that prevents moisture escaping. Cement render or mortar, or plastic-based paints are, in most cases, incompatible with period properties, but we encounter many instances where they have been used. Typically, these have to be removed and replaced with traditional lime-based breathable materials that allow moisture to evaporate.


Wear and tear on older houses can result in leaks that, if not dealt with, can lead to damp problems. Inside a property – this might come from worn water pipes concealed in the walls or old waste pipes in bathrooms. Crumbling grouting and cracked seals around baths and showers is also a place to look. Outside a property – damaged or missing roof tiles, substandard flashing near chimneys, faulty downpipes and loose guttering – can all lead to damp walls.


Blockages to airbricks can cause damp issues. Airbricks were installed in older houses to allow a flow of air under floorboards and into cellars and to allow moisture to escape.  Over time some airbricks can be neglected and get full of mud or old leaves and stop the airflow. Older windows sills also tend to have a groove running underneath them, which prevent any rain and water from running back against the wall. As the sills are painted again and again the grooves fill up and stop doing their job. It’s always worth checking that these grooves aren’t blocked.


If you would like to discuss how we can help you with a damp problem or any other building-related issue, please contact us on either info@charlesclarke.co.uk or 01473 735317.