There's no place like a comfy home, where you can unwind after a busy day. But rising damp is a problem that can really put a dampener on your mood. It has a way of sneaking up on a home, and you may not notice the first signs until it's too late.
What's the difference between rising damp and condensation?
What is rising damp?
Rising damp can occur when moisture at the base of a building starts to rise through porous walls. It requires careful investigation as the symptoms can be confused with rain penetration or rain splash at the foot of a wall.
The use of a damp-proof course (DPC) in house construction has only been standard since the 1870s, so many older Victorian and Georgian homes were built without one. However, lots of these traditional buildings have survived for years without a serious damp problem, and signs of increasing dampness may be due to later changes or inappropriate improvements to the building.
A damp-proof course is a horizontal waterproof material set in the lower courses of masonry walls (brick, stone or concrete) to prevent natural moisture travelling upwards. Later Victorian houses used slate, just like the pieces used on many period roofs. Subsequently bitumen felt was used, and now a polythene strip conforming with British Standards is laid in modern cavity walls.
What does rising damp look like?
You'll usually notice rising damp in the ground floor of a property as stained patches around the bottom metre of an outside wall. One indicator is rusting screws or nails in a skirting board, or even the wood itself rotting. Other signs include deteriorating plaster, peeling paint or wallpaper, and powdery salt deposits and discloration.
If this doesn't sound like what you're experiencing, then you may have a different damp problem. Dampness caused by condensation crops up when the moist air inside your home cools down to what is known as the dew point, or the temperature at which moisture condenses.
Condensation is evident to most of us as droplets on cold tiles and windows in steamy kitchens and bathrooms, and the resulting mould. Plus it's more common in winter, when the outer walls of a building are colder, and the air heated by your central heating can hold more moisture. For instance, you could be drying clothes near a radiator when condensation appears on a single-glazed window.
While the solutions for preventing condensation are different and easier to that of rising damp, the former can make the latter worse. As a start you can improve ventilation by opening windows whenever possible, put a lid on a boiling saucepan (unless its pasta), and dry your clothes outdoors.
How to treat rising damp
Finding the cause
Treating rising damp can be expensive, so you want to be sure of the best remedy before you start any repairs.
If you think you may have rising damp, the first step is to get an expert opinion on whether you actually have it. This will involve looking for the cause or causes of the dampness, especially with regard to the type, age and position of your home. Older properties, pre 1919, may require a surveyor with experience and knowledge of traditional buildings.
But before the expert arrives, you can have a look outside at the external wall where the dampness is occurring. First check whether the wall is solid brick or stone, or else is a cavity wall, and look down for the damp-proof course.
Next, has the ground level, garden border, driveway or patio risen above and bridged the DPC? Or is there a broken drainpipe or drain in the area, or even plumbing leaks. Any of these defects may be the cause, but will require a gradual process of fixing and elimination.
You can also make sure that your house is properly ventilated. Older houses with floorboards on the ground floor (often called suspended floors) usually have a series of brick-size vents just above or below the DPC. Called air bricks, they were orginally cast-iron grills, but were later made of clay or plastic. Modern houses with solid concrete floors don't usually have air bricks at this level. Again, just clearing the vents may solve the problem, or be one step towards reducing the dampness.
It's a good idea to tell the surveyor about any substantial works to the property since it was built. Whether the external wall been rendered or repointed, or replastered inside, and if a suspended floor has been replaced with a solid concrete floor.
How much is a damp-proof course?
Removing the causes of dampness may just solve the problem. The building then needs to dry out, and damaged areas carefully repaired. Of course, the best solution to any rising damp problems is to make sure you have an effective damp-proof course in the walls.
To function as it should, a damp-proof course should be 150mm above the ground level, or about 2 or 3 brick courses.
But as you may have figured out, inserting a DPC into a wall won't be easy. And it could even make the problem worse by forcing moisture elsewhere, especially in older buildings. And this is where help from an expert comes in.
In short, the repair costs will depend on the extent of the damage and the most appropriate treatment.
The Building Research Establishment suggests that any method used to retrofit a damp-proof course should have a certificate from the British Board of Agrément (BBA).
Is rising damp covered by insurance?
Most buildings and contents home insurance policies won't cover you for damage caused by damp and condensation. When you apply for home insurance, you need to agree to a list of assumptions, and one of them is that your home is in a 'good condition'.
For guidance on this an RICS condition report has a summary of the risks to the condition of a building. If your home does have rising damp, then it's not in good condition. Failure to tell your insurer could put you at risk of invalidating your insurance.
Some insurers offer specific cover for rising damp, but generally it's better to carry out regular maintenance on your home to lower the likelihood of damp causing extensive (and expensive) damage.
Having home insurance protects your home from a range of things. You should check your list of policy exclusions to see if you're covered for damp.