How To Treat Damp Walls Internally and Externally?
If you’re experiencing damp on your walls, you’re not alone. Damp walls are a common problem that can be caused by a variety of factors such as leaks, condensation, or even the location of your home.
Damp on walls can lead to a number of issues including the growth of mould and mildew, which can be harmful to your health. They can also weaken the structure of your home and cause damage to your walls and possessions.
If you’re concerned about damp walls in your home, it’s important to address the issue as soon as possible. On this page, we’ll discuss the causes of damp walls and provide tips for identifying and fixing the problem. We’ll also explore some of the most effective solutions for preventing damp walls in the future.
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Damp on Internal Walls
Damp on an internal wall is a common problem in many buildings, indicating excess moisture within the wall structure. This can manifest in various ways: wet patches, discolouration, mould growth, peeling or blistering wallpaper, and a musty smell. Three primary types of damp can affect an internal wall: rising damp, penetrating damp, and condensation.
Damp on External Walls
Damp on an external wall is a common problem seen in buildings. It occurs when water from outside the property seeps into the walls, usually due to defects in the building’s structure or exterior finishings. These defects could be anything from cracked rendering, defective pointing, or issues with the roof, gutters, and downpipes. The damp can also be the result of ineffective or compromised damp proofing.
Causes of damp patches on walls
There are several potential causes of damp patches on walls. One common cause is a leak in the roof, walls, or plumbing. Water can enter the building through these openings and cause dampness on the walls. Condensation can also be a cause of damp walls, particularly in homes with poor ventilation.
When warm, moist air comes into contact with a cold surface, such as a wall, it can condense and cause dampness. Additionally, some homes may be located in areas with high levels of humidity, which can lead to damp walls. In these cases, the damp may be more widespread and not confined to specific patches on the walls.
It is important to identify the specific cause of damp patches on walls in order to properly address the issue.
Other potential causes of damp patches on walls include rising damp and penetrating damp. Rising damp occurs when moisture from the ground rises up through the walls of a building.
This can be caused by a variety of factors, such as the lack of a damp-proof course or the presence of cracks in the walls. Penetrating damp, on the other hand, occurs when water penetrates the walls of a building through external sources such as rain or leaks in guttering.
It is important to address damp patches on walls as soon as possible, as they can lead to a number of issues such as the growth of mould and mildew, which can be harmful to your health. Damp patches can also weaken the structure of your home and cause damage to your walls and possessions. Ignoring damp patches can lead to more serious and costly problems in the future, so it is important to identify the cause and take steps to fix the issue as soon as possible.
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How do I identify rising damp on walls
There are a few key signs that you may have rising damp on your walls:
Damp patches on the lower part of your walls: Rising damp usually affects the lower part of your walls first, so if you notice damp patches in this area, it may be a sign of rising damp.
Tidemarks or “damp rings” on your walls: Rising damp can leave visible tidemarks or “damp rings” on your walls, which are caused by salts that are carried up through the damp walls.
Musty or mouldy smells: If you notice a musty or mouldy smell in your home, it could be a sign of rising damp.
Peeling or blistering wallpaper: If your wallpaper is peeling or blistering, especially in the lower part of your walls, it could be a sign of rising damp.
Damage to skirting boards: Rising damp can cause damage to skirting boards, such as warping or rot.
If you suspect that you may have rising damp in your home, it is important to have it checked by a professional. They will be able to identify the cause of the dampness and recommend the appropriate course of action.
How do I identify condensation on walls
There are a few key signs that you may have condensation in your home:
Damp or wet patches on walls, windows, or other surfaces: If you notice damp or wet patches on your walls, windows, or other surfaces, it could be a sign of condensation.
Mould or mildew growth: Condensation can lead to the growth of mould or mildew, which can appear as dark or black spots on walls, windows, or other surfaces.
Fog or moisture on windows: If you notice fog or moisture on the inside of your windows, it could be a sign of condensation.
Musty or mouldy smells: If you notice a musty or mouldy smell in your home, it could be a sign of condensation.
High humidity: If you use a hygrometer to measure the humidity in your home and it is consistently above 50%, it could be a sign of condensation.
If you suspect that you may have condensation in your home, it is important to address the issue as soon as possible. Condensation can lead to the growth of mould and mildew, which can be harmful to your health and can cause damage to your home.
How do I identify penetrating damp on walls
There are a few key signs that you may have penetrating damp on your walls:
Damp patches on your walls that are not confined to the lower part of the wall: If you notice damp patches on your walls that are not limited to the lower part, it may be a sign of penetrating damp.
Staining or discoloration on your walls: Penetrating damp can cause staining or discoloration on your walls.
Peeling paint or wallpaper: If the paint or wallpaper on your walls is peeling, especially in areas that are not commonly exposed to moisture, it could be a sign of penetrating damp.
Damage to plaster or plasterboard: Penetrating damp can cause damage to plaster or plasterboard, such as crumbling or softening.
Musty or moldy smells: If you notice a musty or moldy smell in your home, it could be a sign of penetrating damp.
If you suspect that you may have penetrating damp in your home, it is important to have it checked by a professional. They will be able to identify the cause of the dampness and recommend the appropriate course of action.
What causes rising damp on internal walls?
Rising damp is caused by moisture rising up through the walls of a building. This can occur when there is no effective damp-proof course in place, or if the existing damp-proof course has become damaged or compromised. A damp-proof course is a layer in the walls of a building that is designed to prevent moisture from rising up through the walls. It is typically made of a waterproof material such as plastic or bitumen.
Other factors that can contribute to rising damp include:
Poor ventilation: Insufficient ventilation in a building can lead to rising damp problem, as the moist air inside the building has nowhere to go and can condense on the walls.
Ground levels that are too high: If the ground level outside a building is higher than the damp-proof course, it can allow moisture to wick up the walls.
Cracks in the walls: If there are cracks in the walls of a building, moisture can seep through them and cause rising damp.
Lack of maintenance: Neglecting to maintain the damp-proof course or other moisture-prevention measures can lead to rising damp.
What causes Penetrating damp on internal walls?
Penetrating damp is caused by water entering a building through external sources such as rain or leaks in the roof or guttering. Some other common causes of penetrating damp include:
Poorly maintained or defective roofing: If the roof of a building is not properly maintained or is defective, it can allow water to enter the building and cause penetrating damp.
Damaged or blocked guttering: If the guttering on a building is damaged or blocked, it can cause water to overflow and enter the building, leading to penetrating damp.
Defective flashing: Flashing is a material used to seal the joints between different parts of a building, such as the roof and walls. If the flashing is defective, it can allow water to enter the building and cause penetrating damp.
Poorly sealed windows or doors: If windows or doors are not properly sealed, they can allow water to enter the building and cause penetrating damp.
Poorly maintained or defective external walls: If the external walls of a building are not properly maintained or are defective, they can allow water to enter the building and cause penetrating damp.
What causes condensation on internal walls?
Condensation on internal walls is caused by warm, moist air coming into contact with a cold surface and condensing. Some common causes of condensation on internal walls include:
Insufficient ventilation: If a building does not have sufficient ventilation, the warm, moist air inside the building has nowhere to go and can condense on cold surfaces such as walls.
Excessive humidity: If the humidity inside a building is too high, it can increase the risk of condensation on walls.
Cold surfaces: If the walls or other surfaces inside a building are particularly cold, it can increase the risk of condensation.
Lack of insulation: If a building is not properly insulated, it can lead to cold surfaces and an increased risk of condensation.
Cooking, bathing, and other activities that produce moisture: Activities that produce moisture, such as cooking, bathing, and drying clothes indoors, can increase the humidity inside a building and the risk of condensation on walls.
How to treat damp on external walls
There are several steps you can take to treat damp on external walls:
Identify the cause of the damp: In order to effectively treat damp on external walls, it is important to identify the cause of the dampness. This could be a leak in the roof or guttering, a problem with the drainage, or something else. Once the cause has been identified, it can be addressed.
Repair any leaks or damage: If there are leaks or damage to the roof, guttering, or other parts of the building, it is important to repair them as soon as possible. This will help to prevent further dampness from occurring.
Improve ventilation: If the cause of the damp is poor ventilation, improving ventilation can help to reduce the risk of dampness on external walls. This can be achieved by installing vents in the walls or by fitting extractor fans in kitchens and bathrooms.
Install a damp-proof course: If the building does not have a damp-proof course, or if the existing damp-proof course is damaged or compromised, it may be necessary to install a new one. A damp-proof course is a layer in the walls of a building that is designed to prevent moisture from rising up through the walls.
Repair or replace damaged or defective external walls: If the external walls of the building are damaged or defective, it may be necessary to repair them with damp proof membrane or replace them.
How to treat damp on internal walls
Issues with walls can be caused by any number of factors such as groundwater, moisture from outside entering the house, or condensation. These three types share some similarities yet have specific indicators as well–stained paint or wallpaper for example that might tell you whether it is structural rather than fungus-based.
Inside walls suffering issues will also show peeling wallpaper and blistering paint on the affected wall. Excess moisture will also break any working damp seal, cause damp problems which lead to black mould growth, and partially negate the efficiency of cavity wall insulation.
From installing a damp course to using a dehumidifier, there are many options available for your damp-proofing walls. It’s also worth discussing a suitable render for the outside of the building with a professional. They can also tell you everything you need to know about hygroscopic salts and how they mix with your walls.
Damp patches often signal condensation; while rising damp is typically accompanied by a tide line that can reach up to 1 metre in height across the affected area of the wall. Meanwhile penetrating damp issues may appear at any level of the property but will have a corresponding defect on the outside of the property, allowing water ingress.
If in doubt, have your internal and external walls, window frames, and over aspects of your property treated to prevent rain penetration and rising damp problems. Failing to do so can damage everything from simple skirting boards to accelerating the rot of decaying timber.
What is the cost of damp proofing internal walls?
The cost of damp proofing internal walls can vary greatly depending on a number of factors, including the extent of the dampness, the cause of the dampness, and the size of the area that needs to be treated. Some simple solutions, such as improving ventilation or repairing a small leak, may be relatively inexpensive. However, more complex solutions such as installing a new damp-proof course or replacing damp internal walls can be much more costly.
In general, the cost of damp proofing internal walls can range from a few hundred dollars to several thousand dollars. It is difficult to provide an accurate estimate without knowing more about the specific situation. It is recommended to get quotes from multiple contractors and to discuss the options with them in order to get a better idea of the potential costs.
How can I prevent damp?
There are several steps you can take to prevent damp in your home:
Keep your home well ventilated: Proper ventilation is important in preventing damp, as it helps to remove moist air from the building. Make sure that your home has sufficient ventilation, such as by opening windows and using extractor fans in kitchens and bathrooms.
Fix any leaks or damage: If there are leaks or damage in the roof, walls, or plumbing, it is important to repair them as soon as possible. This will help to prevent moisture from entering the building and causing damp.
Install a damp-proof course: If your home does not have a damp-proof course, or if the existing damp-proof course is damaged or compromised, it may be worth considering installing a new one. A damp-proof course is a layer in the walls of a building that is designed to prevent moisture from rising up through the ground floor walls.
Insulate your home: Proper insulation can help to prevent cold surfaces and reduce the risk of condensation, which can lead to damp.
Use a dehumidifier: If you live in an area with high humidity, using a dehumidifier can help to reduce the moisture in the air and prevent damp.
By taking these steps, you can help to prevent damp in your home and protect your health and property.
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How to Treat Damp Walls - FAQs
What is the average cost of treating damp walls internally and externally?
The cost of treating damp walls can vary significantly depending on the extent of the issue, the treatment method used, and local labour rates. It’s important to obtain multiple quotes from qualified professionals for an accurate estimate.
Can I treat damp walls myself, or should I hire a professional?
While DIY methods can address some minor damp issues, consulting a professional damp specialist for accurate diagnosis and treatment is generally recommended.
How can I identify the type of damp affecting my walls?
The type of damp can be identified through visual inspection, noting the location, appearance, and smell, or consulting a professional damp surveyor. A damp survey expert will help you with a comprehensive assessment of the affected area, along with the building’s construction and environmental factors.
Rising damp typically presents as a tide mark up to 1 meter high from the ground, with a more robust presence of salts at its peak.
Penetrating damp, on the other hand, often appears in localized areas, possibly around windows or doors, with a horizontal or diagonal pattern that indicates the direction of water ingress. It may also be associated with visible defects on the building’s exterior.
Condensation-related dampness usually forms on cold surfaces, such as external walls or corners, and is often accompanied by black mould growth.
When should I worry about damp walls?
You should be concerned about damp walls when you notice signs of damp. The signs include a musty smell, discoloured patches, peeling wallpaper, or wall condensation. Early intervention can prevent structural damage, avoid costly repairs, and maintain a healthy living environment.
How to stop damp coming through external walls
You’ll need to identify and address the root cause to stop damp from coming through external walls. If the dampness is due to structural issues, such as cracks in the wall or defective pointing, you’ll need to repair these defects first. Applying a water repellent to the external wall can be effective in case of dampness due to rain penetration. For rising damp, a new damp-proof course may be required. For best results, seeking advice from professional damp-proofing experts is good.