What Is Rising Damp
Additional Information
Rising Damp is one of the more elusive forms of damp and is often misdiagnosed with condensation. It can occur on any masonry structure that has not had a properly installed Damp Proof Course. Moisture in the outside ground will rise up through the masonry whether this is Brick, Block or stone work, seeking a means of evaporation.
The moisture rises by capillary action through the pores, micro-scopic tube like structures present in your masonry. The water will continue to rise until it reaches a point where gravity becomes the prominent force pulling the moisture back down, this level very rarely exceeds 1200mm in height, although hydroscopic salt deposits may be found higher. The Hydroscopic salts left over by the evaporated moisture will form a band running above the tide mark from the rising damp.
Diagnosing Rising Damp should always be left to a qualified surveyor to save you the time and money of been miss diagnosed by inexperienced tradesmen, some of the tell-tale signs of rising damp are as followed,
Flaking Wallpaper:
The moisture present in the walls caused by Rising Damp can lead to the wallpaper peeling, usually starting in the corners of any affected walls, Up to a height of 1200mm. Although this can be condensation, by touching the wall with the back of your hand you should feel the damp in the plaster work, if the wall is wet to touch your more than likely suffering with a condensation problem.
Hydroscopic Salts:
Moisture rising from the ground by capillary action contains Hydroscopic Salts, these salts over time will become present at the apex of evaporation of the moisture, this can also be on the apex rise of the external wall, the salt fragments will appear as a white fluffy substance. Left over time the salt deposits can absorb moisture directly from the air leaving the plaster work wet to touch, this will be around the salting area (highest point) of the rising damp. Generally, although this is caused by rising damp it’s classed as an entirely different form of dampness called ‘Hydroscopic Dampness’.
Tide Marks
Usually referred to as the single most common sign of rising damp, a tide mark (Damp Staining), runs along the bottom half of the wall. The height of the tide will vary on how much moisture is present in your walls, usually reaching a maximum height of 1200mm. Yellowish/brown stains appearing along the skirting boards can also be another indication rising damp is present.
Timber Decay
Any timber in contact with the damp wall over a long period of time will be subject to timber decay, excessive moisture content can cause the skirting boards to split, crumble and cause paint work to start flaking, floor boards adjacent to the affected walls can, over time develop wet/dry rot if the problem is not rectified.
