Exterior house painting, Clapham Common:   by The Hamilton Group

​These are the best ways to fix damp in your home

Johannes van Graan Johannes van Graan
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Whether you live in a traditional-style period home complete with original features, or a much more contemporary house with all the latest and greatest touches (like energy-efficient windows and insulation), the changing seasons and unpredictable UK weather can still leave its mark and cause a batch of maintenance issues for you, including damp. 

Nobody wants to share their residence with damp, seeing as even the tiniest little leak can soon evolve into an unmanageable and expensive challenge. That is why firm and swift action needs to be taken if you suspect that you might have damp creeping into your walls.

But before we can fight the problem, let’s find out a little bit more about what causes it.

1. What causes damp?

Signs of damp are often more common between October and April, when the temperature is lower and more rainfall occurs. 

Dampness can be caused by rainwater seeping through defective roof coverings, blocked and leaking gutters, broken downpipes, damaged masonry or internal leaks. These can all increase the levels of moisture indoors, causing wet patches on walls, condensation and mould.

One of the most common causes is condensation, especially in homes that are poorly heated and lack sufficient insulation. Living in an older house and not allowing the structure to ‘breathe’ (by sealing gaps with modern materials like cement instead of traditional lime mortar) could also worsen the problem.

2. The different types of damp: Condensation

Most damp problems stem from condensation due to inadequate ventilation. Moisture from breathing, washing, drying and cooking, if not removed, will condense on the coldest surface, usually on walls and windows. The signs to look out for include a musty smell, black mould, and surface water.

Your best defence is to improve the rate of air changes in affected areas by adding vents, clearing existing ones and fitting extractor fans.

3. The different types of damp: Leaks

A leaking roof can definitely be the instigator of damp. But how do you know if your roof is leaking? Apart from seeing the water dripping indoors, a leak can be identified by a damp patch on the ceiling, or worse, a collapsed ceiling. 

Find the leak and repair the roof, and be sure to repair faulty gutters or remove any blockages.

4. The different types of damp: Penetrating damp

Persistent or driving rain can quickly drench external walls. With modern houses, the moisture should never bridge the cavity to reach inside. With effective protection, any moisture that does penetrate the outer wall should run into a damp proof course, or onto door and window trays, and be channelled away. 

Should you experience this type of damp, identify the faulty building detail and maintain and repair the exterior, or alter the cladding material or add another layer.

5. The different types of damp: Rising damp

If a correctly installed damp-proof course is in place, modern buildings with cavity walls should not suffer from rising damp at all. This type of damp can be identified by spotting discoloured patches on walls that darken when it rains.

The ingress of water usually carries dissolved salts from the ground that form crystals on the wall where the moisture evaporates. Once these are present in the walls or plaster, they attract moisture from the air. 

In order to prevent the damp, remove the source of the moisture by improving ground drainage around external walls, eliminating plant growth against walls, and ensuring ground levels are at least 15-20 cm below internal floor level. 

In addition, ensure the wall can dry out naturally by restoring lime pointing or breathable render and paint finishes, both internally and externally.

6. The signs of damp

If you see any of the following signs in or around your home, you might have a damp problem on your hands:  

• Stained walls or plaster.

• A musty smell.

• Warped wood or damp timber (which, if left untreated, can lead to wet rot).

• Peeling paint or wallpaper mould.

• Water droplets from condensation.

• Salt deposits on walls that leave a tide mark.

7. What to do about it

Fortunately, there are a few actions you can take to limit the extent of the problem:  

• Clear gutters and waterways.

• Fix leaks.

• Add more ventilation.

• Install a dehumidifier.

• Ensure your damp-proof course is intact.

To further fight the onset of damp, adopt a staged approach to make numerous repairs, starting with the most severe. And be sure to keep an eye out for any issues that might make a comeback.

8. The repair costs

Costs will vary depending on the amount of work required to rectify the signs of damp, the extent of the problem, and the type of damp found. Some smaller repairs, which you can carry out yourself, will be relatively low-cost. Treatments for condensation (such as improving ventilation and buying a dehumidifier) may require a larger initial outlay, but will provide long-lasting results.

Penetrating- and rising damp are more likely to cost more to resolve, as a specialist’s expertise may be required. Be sure to always get at least three quotes from independent consultants and obtain a recommendation, or look for trade-body accreditation before employing help.

Take a look at our extensive range of professionals for all your damp (and painting, and designing, and landscaping… ) issues.

9. What to do if you have more than one type of damp

Approach each individual case separately and focus on the appropriate steps to cure each type. Trying to implement a singular, universal solution might just cause further damage to your property or move the problem to another area.

Rather treat each damp source as an individual incident before moving on to the next. 

Before you approach your house with a paintbrush again, make sure you are aware of the: Mistakes people made painting their house façade.

What other tips do you have for us to help combat damp?
Whitton Drive:  Terrace house by GK Architects Ltd

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