Damp patches on walls are a common problem, particularly in older properties. They are typically first noticed when the dampness causes discolouration of the paintwork, or causes the wallpaper to peel. If you’re dealing with a damp patch on your walls and can’t figure out what is causing it, read on to learn the most common reasons damp develops in homes.
What is a damp patch?
Damp is a term used to describe unwanted moisture in the structure of a building. This could be moisture in the air that settles on surfaces, or it could be moisture that has soaked into the building structure, including brickwork and timberwork.
In the UK, damp is common because of the climate. The country experiences a lot of rainfall, which can lead to water ingress through broken roof tiles. This water will eventually make its way into the ground, where it can seep into the foundations of a building and cause damp patches on floors and walls.
Moisture that is generated inside the house can also settle on cold surfaces due to poor insulation and poor ventilation. The colder temperatures in the UK makes this a far more common occurrence.
Damp can be an isolated problem that occurs as a result of poor ventilation, or it can be a structural problem. If you’ve spotted a damp patch in your home and you don’t have a leak, there are a number of other issues that might be to blame.
What causes damp?
Damp is simply caused by an excess of moisture. So to find the cause of your damp patch, you need to find out where the moisture is coming from. The most common causes of damp include:
- Burst pipes
- Leaks in the roof
- Rising damp
- Broken window seals
- Condensation buildup
You may need to arrange a damp survey to determine the cause of your damp problem. Remember that damp problems won’t go away on their own. You need to take action at the first sign of an issue to stop it from spreading.
What is a damp survey?
During a damp survey, a damp specialist will examine the damp areas and determine the cause of the issue. They will use a variety of methods to find out what is causing your damp problem. Once they know what is causing the issue, they can take steps to put things right.
A common method for diagnosing issues with damp is thermal imaging photography. This specialist kind of camera can detect infrared radiation given off by surfaces. This will help the damp specialist to see the damp spots not visible to the naked eye, and then also see the potential source of the damp.
Thermal imaging is a popular choice as it is non-invasive, which means they don’t need to drill into walls or pull up floorboards to see what is going on beneath the surface.
Potential causes of damp
If you have a damp spot on your wall and you’ve ruled out the possibility of a leak, there are a few other potential issues that might be at play. Consider the following:
A leaky roof
A cracked roof tile could allow rainwater to enter your property and this might be visible as damp spots on your walls or ceiling. Cracked roof tiles can lead to a slow and gradual leak of water into your home, which would explain why there is only one patch. The actual extent of the moisture damage may be much wider, but it hasn’t reached the surface of your walls yet.
A broken window seal
Just like a leaky roof, faulty window seals can allow moisture to enter your property. If the damp patch is close to a window, this is far more likely to be the culprit. Feel around your window frames for any damp patches and then address this with a new window sealant. There could also be issues with your double glazing frames.
If your home has poor ventilation, condensation from everyday living might be allowing moisture to build up in your home, leading to damp patches.
Your kitchen and bathroom are the most likely causes of moisture build up in the home, but bedrooms are also moisture hotspots. This is because each person in your home will exhale around 2 litres of water every night. By increasing air circulation, you can limit the build up of moisture that will lead to damp spots.
If the insulation that protects your home is failing or insufficient, this will lead to cold spots on your walls. Common causes of this include old vents which are blocked over but not sufficiently insulated. This may lead to cold spots on your walls which attract any moisture in the air.
One of the main structural issues related to damp is known as rising damp. This can happen when the damp proof course in your outer wall fails, which allows moisture to travel up through the inner cavity wall. This might be first seen as isolated patches if it has damaged your cavity wall ties.
When these break down due to rust and corrosion, the main structural anchor between your cavity wall and outer wall breaks down. This can cause your walls to buckle or collapse, so it should be dealt with as a matter or urgency.
When a broken gutter leads to rainwater hitting the same spot on your external walls, this can lead to damp spots inside. Nearly all building materials are porous and are not designed to have water rushing against them. Gutters are designed to transport the water away so it cannot seep into the building, but gutters can be broken or become blocked.
Damp patches won’t go away on their own, so it’s important to find the underlying cause so that you can treat the issue. It could be a simple case that your home needs better insulation, or you may need to make repairs to the structure of your home to help prevent damp from returning.