This guide will help you understand what damp is, how to identify it and what measures you can take to remove it, plus how you can prevent damp from happening in the future.
What is damp?
Damp is excessive moisture within the structure of your home that can cause multiple problems if not resolved as soon as possible.
It’s recognisable as a concentrated patch of moisture or unsightly discolouration, usually accompanied by a musty smell.
Ignoring damp is not a good idea. Not only does it damage walls and window frames, but also anyone living in a house with damp could develop health or respiratory problems.
Damp repair isn’t covered by many buildings insurance policies as damp is a gradually occurring issue and would fall within the 'maintenance and normal use or ageing exclusion'.
Is damp covered by home insurance?
Most standard home insurance policies don’t cover damage from frost, damp, fungus, mould or condensation.
The worse a damp situation gets, the more it'll likely cost to get repaired. You'll usually be asked to share details about the condition of your home when you apply for cover.
What causes damp?
Damp can be caused by:
- Faulty pipes, guttering or drainage
- High levels of ground around the property
- Blocked vents and airbricks
- Rising damp from cellars
- Rainwater through roof or windows
The signs of damp in a house
You may smell damp before you spot tell-tale signs of damp, but these are some of the things to look out for:
- Stains or patches of mould on walls
- A musty smell
- Excessive condensation on windows
- Peeling wallpaper
- Paint blisters
- Crumbling plasterwork
Types of damp
You'll need to treat each type of damp differently. From mould around windows and doors to any new, unusual smells, there are a number of things to look out for.
There are 3 types of damp; rising damp, penetrating damp and condensation. Let’s take a look at them in more detail.
What is rising damp?
Rising damp is moisture which comes up from the ground, through the structure of your home.
You'll usually start to notice it on the lower parts of walls and across solid concrete floors. Wet weather makes rising damp worse as walls have more water to soak up.
Modern houses are usually constructed with a damp-proof membrane under concrete flooring - often referred to as a ‘damp-proof course’.
What are the signs of rising damp?
- Appearance of damp stains and patches on walls
- Ironwork shows signs of rust
- Loose or rotting flooring or skirting boards
- Crumbling, flaky or salt-encrusted plaster-work
How to fix rising damp
You might want to call a professional to fit or replace a damp-proof course. If you only spot a few wet patches on the floor then the membrane might only be slightly damaged, so painting the floor with a waterproof emulsion might help.
The damp-proof course in the walls should be set to a height of 15cm. If there are any wet patches above this on an exterior wall, you could try checking on the other side in case there's anything causing the moisture, like a raised path or piles of damp earth.
What is penetrating damp?
While rising damp relates specifically to moisture from the ground, penetrating damp can come from anywhere. It might lead to wet patches on the ceiling or towards the top of a wall, which can signal a leak somewhere. Or the bricks themselves may be so old that they have become porous, allowing entire walls to soak up water like a sponge.
What are the signs of penetrating damp?
- Drips or puddles
- Peeling wallpaper
- Crumbling plasterwork
- Patches that turn dark during rain
- Increasing damp circles on walls, floors and ceilings
How to fix penetrating damp
A good start is to check for any leaking pipes, broken or blocked guttering, missing or damaged roof tiles, and that any joints are properly sealed.
If damp on walls is caused by damaged or porous bricks on the outside of the building, you might want to consider replacing them. You can try treating the bricks with a water-repellent product to help damp-proof the walls.
Remember to inspect the door and window frames too. There could be gaps to fill or rotten wood that needs replacing.
What is condensation?
In a home with no real structural problems, condensation might be the most likely cause of damp. Warmth causes moisture to evaporate into the air, and as soon as it hits a cold surface turns back into liquid, covering the wall or window with water droplets. This moisture can sometimes soak into the window frames (making them rot) or into the walls.
What are the signs of condensation?
- Water found on windows or walls
- Rotting and stained window frames
- Peeling wallpaper
- Musty smell
- Spread of mould on fabrics, such as carpets and curtains
How to fix condensation
Often, the best way is to open windows to allow moisture to escape easily. Double glazing and insulation can also make sure that walls and window panes don’t get quite as cold which reduces condensation.
It's also worth checking for areas where condensation might build up unnoticed, like a sealed fireplace, chimney, lofts or basements. Fitting vents and using air bricks can help prevent build-ups.
Damp on outside walls
Damp can start in many places but can also be created by external factors. These include water leaks from damaged roofing, flashing or where gutters have been blocked by tree debris. Another factor is crumbling masonry, render or mortar.
Old brickwork can deteriorate over time, becoming absorbent rather than resistant, while cracks can make problems worse.
Overgrown foliage or even rubbish that has not been cleared in a long time can cause damp to spread through external walls.
How to prevent damp
Preventing damp entails a combination of regular maintenance checks which include tasks that can be concluded without calling in professionals. These include:
- Ensure rooms are well ventilated
- Clear any debris around the property
- Do regular checks to roofing (please do so safely to avoid putting yourself in any danger)
- Make sure all vents are clear particularly in the kitchen and bathrooms
- Make sure kitchens are properly ventilated when cooking
- Air your home
- Use a dehumidifier to extract moisture
How to spot damp when viewing a house
There are some telltale signs of damp to look out for, from damp patches to musty smells.
When viewing a house, asking the right questions is key. Read our buying a property guide for some handy pointers.
What is mould and mildew?
Mould is fungi. Look closely and you’ll see it grows outwards in green or black filaments. Mould can grow on damp services like bathroom walls and trim around windows, and is a danger to health - especially for those with asthma or other respiratory conditions. It can cause allergic reactions that may affect the eyes, nose, throat or lungs.
Mildew is fungi and is usually grey in colour. Look closely and you’ll see a flat or thin layer of filaments. Mildew can be found on damp surfaces from bathrooms to cellars, carpets and curtains and it smells musty. It can grow on most surfaces and is hazardous to health, either by touch or inhalation.
How to remove mould and mildew from walls
Natural solutions include the use of vinegar, distilled in a bottle, and sprayed onto the surface. Then leave for an hour, before returning to scrub the mould or mildew off. This should work for smaller surface areas. If the problem is more widespread then consult a trusted tradesperson for large scale solutions.
How to prevent mould from returning
Once you’ve taken the effort of getting rid of mould, here are six ways to stop it from returning.
- Wash and disinfect surfaces that suffer from mould
- Fix internal or external causes of leaks
- Maintain ventilation and open windows
- Clear any rubbish and debris
- Use a dehumidifier and clean extractor fans
- Clean and dry carpets
The earlier you spot signs of damp, the easier it’ll be to get rid of. So, we hope this guide on dealing with troublesome damp problems and finding out its cause can help you make the most of your living space.