Rising damp, as its name suggests is caused by the upward travel of moisture through brickwork, blocks, renders and plaster, caused by the process of capillary action, which will rely on the surface tension of moisture to allow moisture to travel vertically from the ground level.
Damp walls may be caused by a variety of different situations, and can range from a lack of an sufficient damp course to leaking drains. Although the water ingress can be caused by a easily solved defect, this does not automatically make the job of diagnosing the damp source a simple find, as many professionals will testify to, this can be a difficult and an expensive process.
Water ingress through rising or penetrating damp problems if left for a number of months or even years, may cause serious damage, resulting in blistering and coroded plaster, tiles falling off the walls and mould growth. There are 3 main causes of damp in properties which are Rising Damp, Penetrating Damp and Condensation. This page explains the key issues of rising damp, with comparisons to penetrating damp problems.
Do you think you have rising damp?
If you think you may have a problem of rising damp which could be in a house, flat or apartment you are looking to purchase, or in your existing property, which may have appeared over time or maybe from recent work to the outside of your property or just no damp proof course at all, it is worth looking out for the key telltale signs, as explained in the following.
Tell tale signs
Tide marks and/or damp patches or water marks up to about 1 metre high White, fluffy salts on the wet wall (these are rarely found from other water sources) Fungus or mould on skirting boards.
Some typical reasons as to why the damp is occuring:
Breakdown of damp proof course or not one in place
High external ground levels above internal floor level
Splashing from down pipes
Render bridging the damp proof course
Is it rising damp?
Rising damp does exist, and is visible in a large number of homes, particularly those of a older property, which often did not include a damp proof course. The most common sign to look for is a tidemark at low level up to 1 metre high, which generally will not extend much higher than this.
Rising damp problems that have been in a property for some time, may be exacerbated by hygroscopic salts, which will pull and attract moisture from the air and can increase the height and increase the damp marks on the wall. There are other causes of damp particularly at floor level, which can trick you and lead to the wrong diagnosis. There may be a leak from a down pipe, which is continually soaking the external wall, or it could even be simply due to an overloaded kitchen sink or bath, resulting in water running down the back of the wall and soaking in.