A Guide to Rising Damp
What You Need to Know
- Rising damp is caused when water from the ground spreads into the brickwork by means of capillary action, rising through fine cracks in the masonry.
- Rising damp can affect almost any property, even ones with relatively modern damp-proofing in case. Homes where patios or raised flowerbeds are built right up against the wall can be at particular risk.
- While it usually only affects the bottom one metre of a wall, left unchecked, it can seep higher than fiver metres.
- Since rising damp is often misdiagnosed, even by members of the building trade, it’s worth investing in expert, specialist advice.
- Curling or discoloured wallpaper and wet plasterwork or brickwork can all be symptoms of rising damp.
- If you invest in damp coursing, it’s worth checking to see if the treatment provider is approved by the by The British Wood Preserving and Damp-proofing Association (BWPDA).
- Investing in preventing rising damp is likely to be more cost-effective in the long-term than simply trying to save money and ignore the problem.
What is Rising Damp?
Rising damp is caused when water from the ground spreads into the brickwork by means of capillary action, rising through fine cracks in the masonry. It is usually found only in the first metre or so of the wall.
Since 1875 all new houses built were constructed with a damp course, essentially a membrane or waterproof barrier built into the walls to prevent the problem. However, rising damp can affect any property, however well treated, if the damp protection is “bridged” – or example when a patio, path or raised flowerbed is built against the house above the damp course.
It is less common than you might imagine. However, it is often misdiagnosed by unscrupulous or inexperienced builders. Make sure the problem is not, for example, leaking guttering, faulty or leaking plumbing or condensation caused by inadequate ventilation.
Rising damp will almost always mean damp patches and stains up to about one metre up the wall. Only if it has been allowed to go unchecked will it have spread higher up.
Look at the exposed surface of the brick. Check to see if there are salts forming, that the brick is actually wet – not just the wallpaper or paint, that there is no mould present and whether the skirting board is showing signs of rot.Other easy-to-spot symptoms of rising damp include stained or lifting wallpaper or softening plasterwork.
The common treatment is to install a damp proofing course. This generally involves stripping away the sodden skirting board and plaster to expose the brick up to about one meter. Holes are then drilled and a silicone-based chemical injected into the brickwork. The chemical seeps through the brick and the mortar to form a new barrier against damp. When that is done the wall is re-plastered with sand and cement containing a waterproof additive.
If an external feature like the patio or flowerbed is to blame, the damp can be cured by lowering it below the level of the original damp course and then allowing the area to dry out naturally by opening windows and heating the room.
The work should be of a good standard. There are thousands of damp coursing firms out there. Like any major structural work to your house it is worth getting at least two or three quotes before you commit to the work and you can often also read reviews online to see what other customers thought of your chosen firm’s work.
Whichever company you chose, make sure that they offer a guarantee, usually of 20 years, which is backed by The British Wood Preserving and Damp-proofing Association (BWPDA).
Given that it is moisture that causes rising damp, ensuring your walls are damp resistant is the key to guarding against the problem. So, for example, you should make sure that the plasterwork of your home, and particularly around ground level, is damp resistant.
Additionally, you need to ensure that your walls are properly ventilated. This may mean that you have to invest in specialist barriers against rising damp, such as concentrated thixotropic saline (or siloxane) cream. If you worry your home is not adequately guarded against rising damp, it’s worth consulting an expert and getting a quote as short-term savings can lead to longer-term problems.
- If you suffer from rising damp then mould might also be an issue - read our guide to dealing with mould on walls.
- Rising damp is one of the many things to look out for when buying a property at auction. Follow the link for more.
- Rentokil provide property care and can help identify problems such as damp.