Rising Damp Vs. Penetrating Damp: What's The Difference?

By Author: Cole Walter
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When it comes to damp problems in homes, understanding the difference between rising damp and penetrating damp is crucial. Both types of damp can cause significant damage to the structure of a property, but they arise from different causes and require different solutions. In this article, we’ll explore the distinctions between these two types of damp, how they manifest, and how to address them effectively.

What is Rising Damp?
Rising damp occurs when moisture from the ground seeps up through the walls of a building. This usually happens due to a failure or absence of a damp proof course (DPC), a barrier built into the walls to prevent water from rising. When the DPC is damaged, breached, or missing, the moisture from the soil below the property’s foundations can travel upwards, causing the walls to become damp.
Symptoms of Rising Damp:
Wet patches on walls: The most obvious sign is the appearance of wet patches or tide ...
... marks on the lower part of internal walls. This is because the water tends to rise through the porous materials in the building.

Peeling paint and wallpaper: As the moisture rises, it can damage the paint or wallpaper on the walls, causing them to peel or blister.

Musty smell: Rising damp often causes a musty odor in the affected areas, which can be difficult to remove.

Damage to plaster: As the moisture rises, it can also weaken the plaster, causing it to crumble or deteriorate over time.

What is Penetrating Damp?
Penetrating damp, on the other hand, occurs when water enters the property through external surfaces. Unlike rising damp, which comes from the ground, penetrating damp comes from sources like leaking roofs, damaged gutters, cracked walls, or faulty window seals. Essentially, it is the result of water penetrating through the outer structure of a building due to poor weatherproofing or damage to the property’s exterior.
Symptoms of Penetrating Damp:
Damp patches on walls or ceilings: Water entering the property will create damp patches that are often visible on the interior walls or ceilings. These patches may appear more prominent during or after rainfall.

Staining and discolouration: The walls may also show signs of staining, often in the form of dark patches or streaks. This is caused by the water infiltrating through the wall’s surface and carrying dirt or minerals with it.

Water pooling or dripping: In some cases, water may pool on the floor or drip from the ceiling if the penetrating damp is severe.

Rotting wood or corrosion of metal surfaces: If penetrating damp is left unchecked, it can cause wood to rot or metal to corrode. This is particularly common around window frames, doors, and other wooden structures.

The Key Differences Between Rising Damp and Penetrating Damp
Source of Moisture:

Rising Damp: The moisture comes from the ground below the property and moves upward through the walls.

Penetrating Damp: The moisture comes from external sources, such as leaks in the roof, gutters, or walls.

Appearance:

Rising Damp: Damp marks are typically seen in the lower sections of walls, often forming a uniform tide mark or wet patches that gradually move up the wall.

Penetrating Damp: Damp patches appear in a more irregular or sporadic pattern and may appear at any height depending on where the water is entering the building.

Causes:

Rising Damp: Caused by failure in the damp-proof course, or the absence of one.

Penetrating Damp: Caused by water ingress due to damaged roofs, leaking pipes, or faulty exterior walls.

Damage:

Rising Damp: Can cause internal plaster to break down, wallpaper and paint to peel, and a musty odor in the affected area.

Penetrating Damp: Can lead to more extensive water damage, including wood rot, metal corrosion, and structural weakening, if left untreated.

How to Treat Rising Damp
The treatment for rising damp typically involves the installation or repair of the damp-proof course (DPC). This course acts as a barrier that prevents moisture from rising through the walls. If the DPC is damaged or ineffective, it may need to be replaced. Additionally, a thorough inspection should be conducted to check for any other underlying issues, such as blocked drainage or poor ventilation, which could contribute to the rising damp.
In some cases, the walls may need to be replastered or treated with a damp-resistant solution to help prevent further moisture ingress. It’s essential to consult with professionals for damp proofing in areas like damp proofing Tonbridge or damp proofing Greenwich to ensure the treatment is effective and long-lasting.
How to Treat Penetrating Damp
Penetrating damp requires a more localized approach, depending on the source of the water ingress. Common solutions include:
Repairing leaks: Fixing any leaks in the roof, gutters, or pipes that are allowing water to enter the building.

Sealing cracks in walls: Cracks in exterior walls or around windows can be sealed to prevent water from entering. Professional damp proofing services, such as damp proofing Kensington, can help identify and seal these gaps.

Improving drainage: Ensuring that gutters and downpipes are clear and functional can prevent water from pooling around the building’s foundation and seeping into the walls.

For more serious cases, external waterproof coatings may be applied to the building’s walls to prevent further water penetration.
Conclusion
In conclusion, while both rising damp and penetrating damp result in moisture damage, their causes, symptoms, and treatments are quite different. Rising damp is caused by moisture moving upward through walls from the ground, often due to a failed or absent damp-proof course. Penetrating damp is caused by water infiltrating through external walls or roof structures.
If you are facing damp issues, whether rising or penetrating, it’s essential to address the root cause of the problem. Seeking professional help from companies specializing in damp proofing in Tonbridge, damp proofing in Greenwich, or damp proofing in Kensington can provide long-term solutions to ensure your property remains dry and structurally sound.
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