Basement Damp Proofing

Basement Damp Proofing

What Causes Damp in Basements?

The average UK home will typically deal with a large amount of rain and wet weather throughout the year, which can ultimately lead to damp. You may not be surprised to hear that damp is a common problem in British properties due to the weather. And if your home has a basement, a lack of ventilation coupled with the fact that homes with basements tend to be older can often put the property at a higher risk of damp developing. Damp and mould can appear anywhere in the basement but are more likely to show up on the internal walls. It can be a result of moisture getting in from the outside, condensation from the inside, or problems like a broken damp proof course or ineffective drainage around the home. Basements are particularly at risk since they are normally the coldest area of the property.

So, what are some of the common causes of damp in basements and how do you deal with them?

Basement Damp Proofing

The House Age Can Lead to a Damp Basement

The majority of homes with basements are older buildings, which automatically puts them at a higher risk of damp. Older houses tend to have been built in a way that prioritises allowing them to breathe, in contrast to modern buildings that are constructed with a system of defensive barriers that are designed to keep the moisture out, along with rarely having basements. Having the basement insulated is one of the best ways to prevent damp and mould in your property. However, if you are insulating an older property, there are several things that are important to keep in mind including making sure that there is a vapour control layer for any condensation if you use your basement on a regular basis.

Insulation for Damp Basements

There are several ways that you can insulate a basement to reduce the risk of damp. Since many damp and moist basements are the result of pipework in the basement, the first step is to ensure that you have adequate pipe insulation to prevent leaks and additional moisture. Basement walls, floors and ceilings can also be insulated to improve the thermal performance of the space along with several other benefits including improving the fire safety of the basement and reducing the transfer of noise from the room. There are several products available that are specially designed for basement insulation, including soffit slabs for concrete basement walls.

Other Common Causes of a Damp Basement

Damp and moisture in a basement can be caused by several factors, which include:

Poor Ventilation

Without adequate ventilation, condensation and damp can quickly form in a basement, particularly if you are using your basement for activities that will generate moisture such as washing and drying clothes. To ensure that your basement can be used effectively without suffering from damp and condensation problems, it is important to ensure that adequate ventilation is ensured through the use of vents or extractor fans.

Interior Water Leaks

When trying to identify the cause of the moisture in your basement, an interior water leak should be one of the first things that you check for. A water leak could be coming from a wide range of places in your home including the shower, toilet, sink, washing machine, or a broken pipe for example. In some cases, moisture in the basement located on the ceiling or walls that are placed beneath the bathroom or kitchen will usually indicate that there is an internal water leak at fault.

Gutter and Downspout Problems

Gutters and downspouts are designed to direct the water away from the foundation of your home. If they are no longer functioning correctly or they are completely missing, the rainwater will often be directed towards the foundation of your home instead, where it might lead to damp problems in the basement. The water can accumulate in the soil around your home where it will make its way into the basement.

Poor Grading

Poor grading can often lead to groundwater or rain making its way into the basement. The ground above the foundation of your home should be sloped away from the property rather than towards it. If the water is draining away in the wrong direction, it will accumulate around the foundation and eventually get inside.

Foundation Cracks

If there are any cracks in the foundation of your home, you can expect the water to find them and make its way inside your basement. Sometimes, the water gathering on the foundation due to one of the problems mentioned above could be the cause of the cracks themselves. Floor joists that are not correctly fastened to the walls of the foundation can allow the walls to move, forming cracks that eventually allow the water to enter.


Condensation in the basement will occur when there is warm and moist air coming into contact with the colder basement walls and floor. When the warm air is cooled by coming into contact with these colder surfaces, it will create moisture. Thankfully, condensation issues are often easier and cheaper to solve compared to drainage problems or leaks.

Can a Damp Basement Lead to Health Problems?

Even if you do not use your basement as a key room in your home, it is important to understand the risk that a damp basement can pose to your health. When left untreated, damp will only worsen over time, which can lead to the formation of more serious issues like mould, since it provides mould spores with an ideal environment in which to thrive and grow. Damp and mould in your basement can spread to other areas of your property and can be the cause of serious health issues including respiratory problems and asthma. If you already suffer from asthma or allergies, damp and mould is only likely going to make these problems worse.

Will a Dehumidifier Help a Damp Basement?

To determine how you are going to deal with the damp and moisture in your basement, it is important to make sure that you determine the root cause of the problem. A dehumidifier may be a simple and effective way to deal with damp in your basement if the problem is a result of condensation. If your basement is used regularly for washing or drying clothes, or you have a bathroom in the basement, adding additional ventilation or a dehumidifier can certainly be helpful. However, a dehumidifier is unlikely to be as effective if the damp problems in your basement are caused by something more serious such as ineffective grading, cracks in the foundations or broken gutters. In these cases, you will need to deal with the issue that is causing the damp first before you can get the full benefits of using a dehumidifier in the space.

Basement Damp Proofing – What to Do

There are several things that you can do to damp-proof your basement and ensure that the problem does not get worse or reoccur after you have repaired it.

Fix Issues

First of all, it’s important to repair any larger issues in your home that are causing damp in the basement. Cracks in the foundations, ineffective guttering or water that is draining in the wrong direction towards your foundations will not go away even after you have repaired the damp in the basement, which will only cause the problem to reoccur in the future.

Insulate Pipes

Since internal water leaks are a common cause of damp in the basement, insulating any pipes in the basement and nearby in your home is a key way to ensure that this problem is a low risk. Since pipes are more likely to break and leak when they freeze over, it’s important to add insulation to keep them at the correct temperature and reduce the risk of leaks and burst pipes.

Damp-Proof Treatments

If you are planning to decorate your basement and use it as a main room in the home, choosing damp-proofing undercoats or moisture-resistant paint can be helpful, especially if you are planning to use the basement for moisture-generating activities like showering or washing and drying your clothing.


Adding adequate ventilation to the basement space is an important step in preventing damp that is caused by condensation on the basement walls. When the warm and moist air that is generated in the basement has nowhere else to go, it is going to be directed towards the colder walls – so a good ventilation system is necessary to ensure that it is directed in the opposite direction. An extractor fan will help to remove the moisture from the air and prevent damp, or you can add vents to the basement space.

No matter what you use your basement for, it is often the coldest space in the home and therefore more prone to damp and mould problems. Keep these common causes of basement damp in mind and how to prevent damp from occurring to ensure that your basement is a pleasant and functional damp-free space in the home.

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