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What are the two types of damp?

Damp is a common problem that many homeowners face. It can lead to mold, mildew, and damage to the structure of a building. Understanding the different types of damp is crucial for effective treatment and prevention. In this article, we will explore the two main types of damp: rising damp and penetrating damp.

Rising Damp

Rising damp occurs when groundwater travels up through the walls and floors of a building. It is usually caused by a lack of an effective damp-proof course or a failure of an existing damp-proof course. Older buildings are particularly susceptible to rising damp as they may not have a damp-proof course at all, or the existing one could be deteriorated over time.

The signs of rising damp include damp patches on walls and floors, peeling wallpaper or paint, a musty smell, and even rotting skirting boards. Rising damp can also cause damage to plaster, woodwork, and even furniture if left untreated.

To treat rising damp, it is important to install a damp-proof course. This can involve creating a physical barrier or using chemical solutions to prevent water from entering the building. Other measures, such as improving ventilation and drainage around the property, may also be necessary to combat rising damp effectively.

Penetrating Damp

Penetrating damp is different from rising damp as it occurs when water enters a building through external surfaces, such as walls or roofs. It can be caused by various factors, including damaged or faulty gutters, cracked masonry, or poor seals around windows and doors.

The symptoms of penetrating damp are often seen as localized patches of dampness, usually near windows, doorways, or ceilings. Stains, peeling paint, and wet or crumbly plaster are also signs of penetrating damp. Over time, this type of damp can lead to structural issues, such as decayed timbers and weakened walls.

To tackle penetrating damp, it is essential to identify and rectify the source of water ingress. This may involve repairing or replacing damaged gutters, seals, or masonry. Ensuring proper maintenance of the building's exterior, including regular checks for any potential issues, can help prevent penetrating damp from occurring.


In conclusion, rising damp and penetrating damp are the two main types of damp that can affect buildings. Recognizing the signs and understanding the causes of these damp problems is crucial for effective treatment and prevention. Whether it is installing a damp-proof course or addressing water ingress issues, taking prompt action is vital to protect the integrity of a building and the health of its occupants.


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