Excess damp and mould on a wall

How to Prevent Damp Walls?

Key Takeaways

Causes of Damp Walls: Damp walls can result from various sources, including rising damp, condensation, and penetrating damp. Rising damp involves groundwater travelling up through porous building materials, bringing salts and minerals, leading to visible damp patches and potential structural damage. Condensation occurs when warm, moist air meets cold surfaces, resulting in water droplets on walls. Factors like poor ventilation contribute to condensation. Penetrating damp occurs when moisture from outside enters walls through cracks, leaky roofs, faulty gutters, or other openings in the building envelope. Prevention Strategies:
  • Ventilation: Ensure good airflow by opening windows, using fans, and maintaining overall ventilation.
  • Temperature Control: Maintain a moderate indoor temperature to prevent condensation on walls.
  • Fix Leaks: Promptly repair any leaks, whether from roofs, pipes, or faucets.
  • Gutter Maintenance: Ensure gutters and downspouts direct water away from walls effectively.
  • Seal Cracks: Fortify the house by sealing cracks to prevent moisture infiltration.
  • Dehumidifiers: Use dehumidifiers in damp-prone areas to remove excess moisture.
  • Moisture-resistant Paint: Apply paint with moisture-resistant properties to create a protective layer.
  • Plant Care: Avoid overwatering indoor plants to prevent excess humidity.
  Damp can occur anywhere in a house. But the most common place where damp shows up is the walls. Walls are a significant point of contact with both ceilings and the ground; they are a frequent breeding ground for various damp types such as rising damp, penetrating damp, condensation, etc. Rising damp is one such damp type that always shows up on walls, whereas penetrating damp can come from walls, ceilings, or ground. However, walls suffer the most when it comes to damp. So, how do you prevent damp from happening on the exterior walls of your house? Well, there are some ways that can help, which we will talk about in this article today. So, keep reading till the end. A wall having a rising damp issue  

What Causes Damp Walls in the First Place?

To remedy damp walls, first, identify the source of the moisture by inspecting both inside interior walls and outside your property. Damp patches can be caused by rainwater seepage, condensation, leaky gutters, broken roofs, damaged downpipes, plants damaging walls, rising damp, roots impacting foundations or damp courses, poor door and window sealing, and cavity wall insulation concerns. Black mould spots on a wall Once you've identified the problem, you should solve it before dealing with the moisture in cold walls of your house. Here are some reasons why the walls of your home are incurring damp:

Rising Damp

Rising damp is a phenomenon where groundwater travels up through the porous materials in a building's walls, usually masonry, due to capillary action. Imagine a sponge touching a puddle – the water starts climbing up the sponge fibres. In this case, your walls act like that sponge, drawing water up from the ground. Now, the water isn't pure. It brings along salts and minerals from the soil as it rises. When the water reaches the surface of the wall and evaporates, these salts are left behind, creating visible damp patches. Over time, this process can lead to structural damage and create an environment where mould thrives, contributing to a musty, damp smell throughout. Black mould stains and cracks on a wall due to damp Common causes of rising damp include a lack of a practical damp-proof course (DPC), which is a barrier built into the walls to prevent moisture from rising. Without a proper DPC or if it's damaged, rising damp becomes an intruder. So, rising damp isn't just water seeping through walls; it's a process that involves capillary action, salt deposition, and potential long-term damp issues for walls in your house. Bubbling of plaster on a wall due to damp


Condensation is a troublemaker when it comes to damp, and it's often responsible for those annoying damp patches on walls. When warm, moist air meets a cold surface, it chills out and can't hold onto all its moisture. So, it releases water droplets, and that's condensation. Now, walls, especially if they're a bit on the chilly side, make a perfect landing spot for these water droplets. For example, it's a cold day, and you've got warm air inside your cosy home. This warm air meets the cold surface of your walls (usually outer walls or uninsulated ones), and beads of water form. Over time, this moisture buildup can lead to damp patches and sometimes even mould growth. Factors like poor ventilation, inadequate heating, or just daily activities like cooking and showering can contribute to condensation. To tackle this, it's all about keeping things well-ventilated, maintaining a balanced indoor temperature, and possibly using dehumidifiers to kick excess moisture out. Damp moisture and stains on a wall

Penetrating Damp

Penetrating damp is an unwanted guest that finds its way into your home through walls. Penetrating damp happens when moisture from the outside of the house manages to make its way through your walls. It's not picky – it can come from leaky roofs, cracked walls, faulty gutters, or any opening in the building envelope. So, let's say there's a crack in your wall. When it rains, water takes the opportunity to come in. If your roof isn't doing its job, rainwater might find a way through. Even if your gutters are not working well and not directing water away, you're in for some penetrating damp problem. Once this water infiltrates your walls, it starts causing trouble. It can leave ugly stains, create damp patches, and make your walls feel perpetually damp. Worse yet, if left unchecked, it can lead to structural damage and mould growth on internal walls, making it a real headache. To battle penetrating damp, fix those cracks, make sure your roof is watertight, and keep those gutters in tip-top shape. Damp patches and cracks on house wall

What Else Can Cause Damp on Walls?

Leaking Pipes If you've got water pipes hiding in your walls, a leak can be a silent culprit. The constant drip-drip can lead to damp, and it might not be noticeable until the damage is done.

Cavity Wall Insulation Issues

While insulation is fantastic for energy efficiency, if it's not installed correctly or if there are issues, it can trap moisture and lead to damp problems.

High Ground Levels

If the ground outside external walls of your home is higher than the internal floor level, it's an invitation for damp. Water can easily find its way through walls in such scenarios.

Lack of Ventilation

Poor ventilation can contribute to damp by trapping moist air inside. Areas like bathrooms and kitchens are especially prone to this if not adequately ventilated. Dark stains and peeling of paintwork on a wall  

How to Prevent Damp on Walls?

To prevent damp walls:

Ventilation is Key

Your home needs some fresh air. Open up those windows, turn on the fans, and let the air flow. Good ventilation helps kick out the stale, moist air, reducing the chances of damp.

Control the Temperature

Your house must be not too hot, not too cold. Keeping a moderate temperature helps prevent condensation on your walls. It's like finding that sweet spot where moisture doesn't want to hang around. Efflorescence and dampness on a wall

Fix any leaks

Leaks are the troublemakers. Whether it's a dripping faucet, a roof leak, or pipes playing hide-and-seek, fix them pronto. The less water sneaking around, the better.

Check Your Gutters

Gutters and downspouts are essential, directing water away from your walls. Make sure they're doing their job so your walls don't end up soaked. Exterior wall of a house affected by damp

Seal up Cracks

Cracks are the weak points in a house. Seal them up to keep moisture from infiltrating. It's like fortifying your home against the sneaky advances of damp air.

Dehumidifiers are Your Friends

The dehumidifiers are like moisture vacuum cleaners. Place them in areas prone to damp, and they'll suck up excess moisture, keeping your walls high and dry. Fluffy plasterwork due to dampness

Use Moisture-resistant Paint

Paint is like a raincoat for your walls. It forms a protective layer, making it harder for moisture to seep in. It's like giving your walls a stylish and practical shield.

Don't Overwater Indoor Plants

While they add life to your space, overwatering them can lead to excess humidity. Be the cool plant parent – water them just enough to keep them thriving without turning your home into a mini rainforest. Peeled paint work on a wall due to damp  

How to Treat Walls if They Have Damp?

Dealing with damp walls requires a bit of work and some hands-on action.

Identify the Source

  • Check for leaks: Inspect your roof, pipes, and gutters for any leaks. Fixing these can often solve the damp issue.
  • Assess ventilation: Poor airflow can lead to damp. Make sure your home is well-ventilated, especially in areas prone to moisture buildup, like bathrooms and kitchens.

Clean and Remove Mould

  • Use a mould-killing solution: Mix water with a mould cleaner or create a solution of water and white vinegar. Scrub the affected areas thoroughly to remove any mould or mildew.

Repair Damaged Areas

  • Peeling paint or damaged plaster: If you spot any, it's crucial to repair these areas. Remove loose paint or plaster, let it dry, and then apply a suitable sealant or filler.

Consider Waterproofing

  • Apply waterproof paint or sealant: Once the walls are clean and repaired, consider applying waterproof paint or sealant. This acts as an additional barrier against moisture.

Monitor and Maintain

  • Keep an eye out: Regularly check for any signs of damp or mould. Early detection can prevent a minor issue from turning into a big headache.
  • Maintain good ventilation: Ensure proper airflow by using exhaust fans, opening windows, or installing a dehumidifier in areas prone to damp.

Seek Professional Help if Needed

  • If the issue persists or if you're unsure about the extent of the problem, it might be worth calling in a professional. They can conduct a thorough inspection and provide targeted solutions.
  Peeling paintwork due to dampness on a wall

What Happens if You Don't Treat Damp Walls?

Here's a detailed scoop on what happens if you give the cold shoulder to damp walls:

Unwanted Odours

Ignoring damp is like an open invitation for funky smells. The damp environment becomes a breeding ground for all sorts of odours – musty smells, mouldy, and just plain unpleasant. It's not the aromatic vibe you want in your living space.

Mould Takes Over

Once damp sets up, it spreads like wildfire. Your walls can incur patches of green, black, or brown colour. It's not just about looks; black mould and spores can trigger allergies and respiratory issues, playing havoc with your health.

Structural Damage

Over time, persistent damp can weaken the structural integrity of your walls. You might end up with cracked walls, peeling paint, and even damage to the foundation if you let it go on for too long. Wall affected due to rising damp

Health Hazards

Mould isn't just unsightly; it can be a health hazard. Breathing in mould spores can lead to respiratory problems, allergies, and other health issues. It's not something you want to compromise on, especially if there are kids or folks with respiratory conditions around.

Aesthetic Nightmares

Your once-pristine paint job becomes a casualty. The moisture seeps into the walls, causing paint to peel, crack, or bubble. Your vibrant colours might turn into a sad, flaky mess.

Increased Energy Bills

Damp can mess with your home's insulation. Wet walls don't insulate as well as dry ones, meaning you might find yourself cranking up the heating more often. That's not just bad news for your comfort; it's also reflected in higher energy bills. Wall of a house affected by rising damp  


Addressing damp issues in walls is paramount, considering their susceptibility to various types, such as rising damp and penetrating damp. Given their pivotal role as a point of convergence between ceilings and the ground, damp proofing walls will demand focused preventive measures. Rising damp manifests exclusively on walls, while penetrating damp can originate from ceilings or the ground, intensifying the vulnerability of walls. To safeguard your home from damp-related concerns, a comprehensive understanding of prevention methods is essential.  

How can you damp-proof a wall?

To damp-proof a wall, you can employ various methods depending on the specific situation. One common approach involves applying a damp-proofing membrane or coating to the exterior surface of the wall, creating a barrier that prevents moisture from penetrating.

How do you stop damp coming through walls?

To prevent damp from coming through walls, it's essential to address the root causes. This may involve improving ventilation within the affected area, using dehumidifiers, and fixing any leaks or water seepage. Applying waterproofing agents to the interior wall surfaces can also help create a barrier against moisture ingress.

How do you stop damp walls in winter?

Proper insulation is crucial to combat damp walls in winter. Cold surfaces are more prone to condensation, leading to a damp wall. Adequate insulation helps maintain a consistent temperature, reducing the likelihood of condensation. Additionally, maintaining good ventilation, especially in areas prone to high humidity, can contribute to preventing damp during the colder months.

What are the leading causes of damp walls?

The leading causes of damp walls typically include water leaks, rising damp from the ground, condensation, and inadequate ventilation. Water leaks may result from damaged roof structures or plumbing issues while rising damp occurs when moisture moves upward through porous building materials. Condensation often arises from temperature differentials and insufficient ventilation, leading to the accumulation of moisture on surfaces.

Table of Contents

Picture of Sam Fitzgerald – CSRT Damp Surveyor

Sam Fitzgerald – CSRT Damp Surveyor

Author – CSRT Damp Surveyor
Sam is a highly qualified and seasoned damp surveyor with over ten years of specialised experience. With a strong academic foundation in building surveying and numerous professional certifications, Sam has established himself as an authority in the field of damp diagnosis and remediation.

At Damp Surveyors Ltd, Sam applies his extensive knowledge to help homeowners across the UK address and solve their damp issues effectively. His approach combines cutting-edge techniques with a commitment to honest, client-focused service, ensuring that every survey and recommendation is tailored to the specific needs of the property.

As a thought leader, Sam’s insights into damp prevention and treatment have been featured in industry publications, underscoring his role as a trusted expert dedicated to maintaining the integrity and comfort of your home.

Testing device for measuring dampness in a house


At Damp Surveyors Ltd, we stand out as your premier choice for damp survey services in the UK. Our commitment to excellence and customer satisfaction sets us apart. Here’s why you should choose us:

  • Exclusive 3 Free Quotes: We offer a one-of-a-kind optional service where you not only get our top-notch damp survey but also receive 3 free quotes from vetted local companies, giving you peace of mind by saving you thousands on getting the most competitive quotes, and also time researching and contacting other reputable companies.
  • Knowledge and Experience: We provide unmatched knowledge to every survey we conduct thanks to our team of seasoned professionals and years of industry experience. This guarantees accurate assessments and practical solutions.
  • Nationwide Coverage: Whether you’re in a bustling city or a rural area, our services extend across the UK, making us accessible wherever your property is located. Choose us for nationwide reliability and excellence.

Choose Damp Surveyors Ltd as your reliable partner for all-inclusive survey needs. Our top concerns are the health and safety of your property, and we are committed to providing outcomes you can trust.

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