Rising Damp is caused by the slow movement of moisture up through micropores within the fabric of a building. Pretty much all building material such as brick, mortar, timber contains micropores and it is these porous holes which allow moisture to be drawn upwards through capillary action. This is where water travels upwards, by being drawn up through the microscopic holes. We often liken this process to how a candle draws up oil in order for a flame to burn.
Rising damp is a slow process and can rise to a considerable height if left untreated, typically 1metre is the norm, but our damp surveyors often find rising damp up to heights of around 1.2m. The moisture typically stops at a height where gravity counteracts the upwards force of the capillary action; the exact height varies depending on a host of environmental and physical factors, including pore diameter. Typically heights of 1m to 1.2m are usual. When the moisture rises it draws with it ground water salt deposits, including nitrates and chlorides. The may be seen slightly higher up, due to the presence of non-breathing wall coverings such as vinyl wallpaper, laminates and non-breathing plasters paints and renders.
Often we find rising damp occurring in properties that were constructed prior to 1875 and therefore typically don’t have a damp proof course (DPC). On other occasions it’s where the DPC has been bridged, such as when block pavior driveways have been laid, so as to bridge the DPC or take the finished ground height to less than 150mm (2 brick courses) above the ground. On other occasions render or high ground levels have caused bridging, or extensions have removed DPCs. So what is a ‘Damp Proof Course’ we’re often asked, well think of it as acting like a physical barrier, stopping moisture from rising up through your walls. A damp proof course (DPC) is simply a piece of waterproof material. Slate or bitumen materials were mainly used from 1875 up until 1950; since 1950 butyl rubber and plastic sheet (polythene) material is more common.
How does it affect your home you may well ask, well Rising damp affects inernal walls by causing tidemark like staining, efflorescent salt damage to plasterwork, blowing plaster, causing rot to skirting timbers and causing wallpaper to lift. Often our independent damp surveyor, Stuart finds that the rising damp has caused the temperature of a wall to drop, consequently if high water vapour is present in the home, this can condense upon coming into contact with the cold surfaces, can condense forming the environment for mould spores to also develop.
As independent and specialist damp experts, registered with the PCA, Healthy Abode will inspect the property and confirm the type of damp your home is affected by. We’ll also determine the cause of the rising damp; faulty or non-exist damp course and recommend treatments to reduce the problem and prevent further rising damp. When our damp surveyors, Stuart is in your home why not get him to also look at all the other areas, he’ll likely find some more defects and can give you further remedial advice, so you can eliminate the problem, before decay or damp becomes notable.