Often misdiagnosed, rising damp is accountable for a small percentage of damp cases in the UK. Because it’s often misdiagnosed, many homeowners waste money on inadequate remedial action which fails to eradicate the problem and the effects of damp.
What is rising damp?
Rising damp usually occurs when water is sucked upwards into masonry from ground level. This works in the same way that a sponge absorbs water when placed on a wet surface. The majority of houses have a damp proof course in place to prevent this. A damp proof course consists of layers of waterproof materials laid into the foundation walls of a property, near to the ground to prevent dampness from rising into the building.
Is rising damp a myth?
Contrary to what many people believe, rising damp is not just a myth, and is present in a number of homes, particularly those from the Victorian era which very rarely have damp proof courses. However, it’s true that rising damp is a relatively uncommon occurrence.
How high does rising damp rise?
The height in which rising damp will rise depends on various factors such as the type of paint on the wall, the size of the pores in the wall, and the level of dampness in the ground. In the majority of cases, rising damp is very unlikely to rise any higher than 1.5 metres. In very extreme cases of rising damp, moisture can rise more than 2 metres up a wall.
Identifying rising damp
An important thing to remember when trying to identify rising damp is that there are numerous forms of damp that can affect a home and a multitude of damp proofing methods to help treat that particular problem. If you do identify rising damp, it’s recommended that you treat it as early as possible. Below are some of the most common signs of rising damp:
- Discoloured or curling wallpaper
- Damp stained walls
- Wet brickwork or plasterwork
- Rotting timber or skirting boards
- Staining or discolourisation of exterior brick
- Damp patches and staining approximately 1 metre up a wall
Causes of rising damp
- Inadequate damp proof course – A damaged or inadequate damp proof course that is unable to cope with changing conditions such as a rise in ground level.
- Poor sub-floor ventilation – Inadequate ventilation in the sub floor leads to a buildup of humidity and means that only minimal evaporation from the base walls and the soil occurs.
- Poor drainage or damaged guttering and pipes – If you have inadequate drainage and sloping grounds, water can get directed underneath your house. If your gutters, roofs, or downpipes are damaged, this can lead to excess leaking which is the most common cause of damp problems.
Rising damp treatment
The most common method for treating rising damp is the installation of a damp proof course. Installing a damp proof course generally involves stripping away the skirting board and plaster to expose the brick up to a level of approximately one meter. A silicone based chemical is then injected into the woodwork via drilled holes. The silicon based chemical then acts as a barrier against any damp. When the damp proof course has been installed, the wall is then re-plastered with sand and cement that contain a waterproof additive.
Another form of rising damp treatment is the Electro-Osmotic process. This involves the introduction of a tiny electric current into the wall just above ground level via a series of copper anodes that are inserted into the brick. The charge rejects the rising moisture molecules and directs them down the walls and back into the ground. If this positive charge is maintained, the protected walls will remain bone dry and completely free of damp.
Different damp coursing companies have different approaches, so please note that treatment methods may vary. If you are considering rising damp treatment, it’s worth obtaining at least two or three quotes before you commit to any work.
This article was contributed by David at Protectahome