Black mould covering walls in a house

How To Treat Damp Walls Internally and Externally?

Damp walls in and around the house are a big problem facing homeowners. It is important to find the source of the problem and treat it as soon as possible. There are many different types of dampness, meaning the way to treat damp on walls differs too.

Damp patches on the internal walls of your home can be a real pain as they are not only visually unappealing to look at but also the moisture and dampness on walls can cause mould.

Mould can have implications for your health, especially for sufferers of asthma and allergies. Having cold damp internal walls can also make your room feel colder and more uncomfortable to occupy.

How to Know If You Have Damp Walls

One way of finding out if damp is present on walls is by using the back of your hand against the wall.

Although this isn’t the most accurate way to ascertain the severity of the issue, by feeling the damp area compared to a dry area on the wall it can give you a good indication of how bad the damp on your wall actually is.

Request a survey

Worried about Damp Walls? Call 0800 288 8660 or

Peeling wallpaper revealing black mould from damp

Identifying Condensation on walls

Condensation forms by the moisture been absorbed into warm atmosphere of a property, then, as the property cools down, the excess moisture condenses on cold surfaces such as on windows or windowsills.

The reasons for this occurring can be numerous – for example it could be down to the fact that there are cracks in the wall allowing draughts and air flow into the property, or as a result of no constant air flow of ventilation in the property.

Penetrating damp on walls outside a home

Identifying Rising Damp on walls

Rising damp will only affect walls on the ground floor of a property. Usually, there are horizontal brown or discoloured marks that can be seen up to 1 meter in height on interior walls, these are otherwise known as ‘Tide Marks’.

The signs of a rising damp issue can also be felt through the fabric of the wall with the bubbling of the plaster that is caused by the continual expansion and contraction of salt crystals drawn from the ground.

Rising damp on walls

Identifying Penetrating Damp on walls

Penetrating damp occurs on the exterior of a property and can cause serious damage to the building if not treated correctly. You may notice damage to the internal walls of the property with watermarks being found on the masonry.

Where there has been heavy rainfall, the rainwater usually evaporates out of the brick. In some cases though, the moisture falls to evaporate though and is then allowed to pass through the inner surface of the wall.

What Causes Rising Damp on Internal Walls?

Rising damp is caused by moisture rising up through walls of a building. This process of water from the ground being ‘sucked’ up through the brickwork is also known as capillary action.

Rising damp is more commonly found in the older buildings where the damp proof course (DPC) has become damaged over time. There are even cases, usually in very old buildings, where there is no DPC present to provide protection against rising damp.

If the paths or driveways have been raised above the damp-proof course then this can also cause rising damp to occur.

What Causes Penetrating Damp on Internal Walls?

Penetrating damp is commonly found where the property is poorly maintained and there have been periods of heavy rain. An example of poor maintenance is damaged rainwater goods e.g., drainage gutters and downpipes.

If the water is not taken away effectively by the rainwater goods then water could penetrate through the external walls and into the internal walls of the building.

If penetrating dampness goes on to affect the timber within your building then dry rot and wet rot growth can occur which can lead to serious structural damage.

Black mould is another issue that can occur and, after a period of time, if left without any treatment, can lead to health issues for people living within the property.

Request a survey

Worried about Damp Walls? Call 0800 288 8660 or

What Causes Condensation on Internal Walls?

Condensation is a common damp issue found in properties across the UK and is largely caused by having poor ventilation within the property or a build up of moisture from homeowners carrying out daily activities such as cooking or bathing.

Condensation appearing on walls is easy to remove but if the poor ventilation issue is not rectified early enough, can cause black mould growth to occur.

How to Treat Damp On External Walls

The most common form of dampness on external walls of a property is penetrating damp. This form of dampness is caused predominately where there is heavy rainfall and there are property maintenance issues that need to be rectified. Treating penetrating damp on walls can be carried out through the following methods:

Penetrating Damp:

  • Repair any masonry defects e.g. cracks in walls. If there are any problems then this will need to be fixed with a suitable render. Using a masonry protection cream on the external walls can help prevent rain penetration.
  • Remove any excess moss and leaves from roofs and gutters. If leaves and plants start to build up in the rainwater goods then this can lead to leaks and water seeping into the walls of the property.
  • Improve the heating of the property and insulate the cold walls.

Rising damp can also occur on the external walls of the building and is usually caused by having a damaged damp proof course. The following treatments are listed for damp proofing walls:

Rising Damp:

Osmotic Damp Proofing

  • Installation of a Damp Proof Course (DPC) and Damp Proof Membrane. This is an inexpensive expensive method of treating a damp problem that will prevent any further deterioration to the building and will be preventing rising dampness in the near future.

How to Treat Damp On Internal Walls

Having damp patches on the internal walls of the property is most likely to occur as a result of condensation. When warm, damp air condenses onto cold surfaces such as walls, mould can start to develop.

The most efficient method of treating damp from forming on the interior walls of the house and therefore preventing mould growth from occurring is through improving the ventilation throughout the property. The below methods are ways of curing damp on internal walls:


Envirowise EnergySaver Positive Pressure Ventilation

  • Improving the ventilation e.g. add kitchen and bathroom fans where necessary. Allow the fan to run for a long period of time to allow any moisture to be cleared from the room.
  • Use a Condensation Mould Kit to remove any mould from walls and surfaces. Once the mould treatment has been applied then this can be painted with a damp seal which ensures that the staining will not seep through the emulsion paint.
  • Improve the heating of the property and insulate the cold walls.

Damp in walls can also occur from rising damp. If groundwater rises up the inner walls of the property this can cause damage to skirting boards, plaster peeling off walls as well as black mould growth.

Treatment for rising damp is usually done by one of two methods:  Either by having a chemical damp proof course or by having a damp proof membrane fitted.

What Is the Cost of Damp Proofing Internal Walls?

Treating damp on your walls should be carried out by a professional to make sure that the problem is dealt with once and for all but what is the cost to treat damp walls? The prices can vary depending on what type of treatment you need carrying out.

Other factors that affect the cost of damp proofing walls is where the damp is located in the building and the severity of the damp problem.

Always make sure that the company you use is reputable and that they have the necessary qualifications before carrying out the work.

If the company is registered with the Property Care Association, you know that the surveyors and technicians will have had the training required to provide expert advice and provide a high standard of service.

Request a survey

Worried about Damp Walls? Call 0800 288 8660 or

What Steps Can I Take To Prevent the Dampness From Getting Worse?

The first step you should always consider when looking to prevent your damp problem from getting any worse is to contact a damp specialist.

Employ the services of a qualified surveyor who will be able to identify the damp issue and provide advice on what effective treatments could be used to remove the damp issue effectively and efficiently.

So, what steps can be carried out by yourself to make sure that the damp on internal walls is not a problem?:

  • Check your downspouts and gutters regularly to make sure that they are not blocked or leaking
  • Make sure the heating in the property is set at an even temperature around the whole house to help eliminate cold spots.
  • Open windows and doors in your property and move furniture away from the walls to allow air to circulate more freely throughout the building.
  • Use extractor fans, especially in areas of the property where moisture content is more prominent e.g. the bathroom or kitchen.
  • Check that there are no cracks in the walls of the building to allow water to penetrate and make its way through to the inside.

Do You Have Damp Walls at Your Property?

It is important that dampness in your property is correctly identified to ensure the right treatment is carried out.

Timberwise has over 5 decades of experience in providing solutions to all manner of damp problems. Find out what happens during a damp survey which might give an insight into the start of the process of treating any of your damp issues. Call our experts today on 0800 288 8660 or click below to arrange a survey online.