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How to Diagnose the Different Types of Damp

Whether you are looking to buy a home to live in, rent out or renovate as a project, it is always important to survey the property before committing to buy. Here in the UK, especially London, there is a wide range of houses on the market from all era’s and in all conditions. Unfortunately, some of them may be harbouring issues under the surface!

Buildings of all ages can suffer from damp, so it is important to be vigilant when you are viewing potential properties. There are three main types of damp that can cause big problems, meaning that knowing what to look for is essential.

Older buildings, particularly those without central heating, are most prone to damp. This is because, unlike new builds, older buildings have not been designed sufficiently to allow moisture to escape.

Some types of damp are much easier to treat and manage than others and are more commonplace in privately rented accommodation (9.3%) than those rented through a housing association (4.4%) or owner occupied homes (2.6%). This means that landlords and potential buyers are the most likely to be the ones to seek a damp proofing survey to identify and address the issue.

Knowing what to look for will ensure that you don’t get any nasty surprises down the line, so we have put together some signs to look out when trying to identify different types of damp.


Condensation is by far the most common cause of damp. This is mainly due to buildings that trap moisture, either due to architectural design or the fact that windows have not been sufficiently opened to allow water in the air to evaporate.

This will eventually lead to mould appearing, often around window frames with unsightly black patches forming on walls, which will require constant removal. Investing in dehumidifiers is one step on how occupants can manage damp in the home, although this by no means will fix the underlying issue.

By installing ventilation systems in affected rooms – most commonly the bathroom and kitchen (although all rooms can be affected) – this allows for the building to breathe, let excess moisture in the air leave without causing damage and also helps with treating condensation.

Rising Damp

If you notice damp patches on external walls – possibly exhibiting moss – or internal damp at low levels, this is a sign of rising damp. Rising damp occurs when water at ground level rises up through the walls.

Most new builds will include a damp proof course (DPC) which prevents moisture from rising in this way, although it can become compromised so always be prepared to investigate. This may result in having to inject a chemical damp proof course above the original DPC and the removal and replacement of internal plastering.

Penetrating Damp

Similar to rising damp, the symptoms of penetrating damp include dark patches on walls and can expand across the ceiling. However, this will be in a horizontal movement, rather than rising, and is usually caused as a result of structural problems and external issues such as gutter defects.

Cracks in the wall or roofing will result in internal walls and the ceiling becoming damp during rainfall, as the water is allowed into the internal structure. If you suspect penetrating damp, you should check your loft for leaks coming through the roof and also investigate the exterior of the building for cracks, gutter leaks or loose pointing.

Arrange Your Damp Proofing Quote Today

Dealing with untreated damp in any property can be a headache that you can’t afford or need, especially if you are renting out your property to tenants. Tackling the issue at the source before it takes hold is the best way to keep on top of it.

For more information on the different types of damp that can affect your home, or for a damp proofing quote, please call our team on 0208 535 7536 today or contact us directly.

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