How to Identify and Treat Rising Damp...
What is rising damp?
‘Rising damp’ is the movement of moisture from the ground into permeable walls of buildings, which can result in aesthetic and structural damage.
What causes rising damp?
As a result of inter-molecular forces between ground water molecules and the mineral surface of walls, the water molecules are able to flow into pores in the walls in an upward direction ('Rising Damp'). This is called capillarity.
Water will continue to rise through the walls until it can evaporate or until the counteractive force of gravity pulls the water downwards. As a result, rising damp only occurs on ground floor levels and rarely exceeds a height of 1 metre.
Is your property suffering from rising damp?
The most common identifiable symptoms of rising damp are as follows:
- Tide Marks on ground floor level walls.
Rising damp can generally be identified by a tide mark or damp line which can be seen on the internal surface of the wall up to approximately 1 metre and by the use of a Damp Detector (Product Code: N03800). If rising damp is present the moisture reading above the tide mark or rising damp line will be substantially lower than the readings taken below this point.
- Patches or areas of damp and staining may be seen up to approximately 1 metre on ground floor level walls.
- Salts (chlorides and nitrates) and/or signs of efforescence (white salting) may be present.
The water that rises into the walls will carry minerals from the soil. Where there is evaporation of the rising damp through the walls, these minerals will be deposited on to the surface of the wall. These salt deposits may be visible and can be felt if you run your hands around the area in which rising damp is suspected.
- Rising damp may also result in moisture in timber skirtings where they come into direct contact with a wall suffering from rising damp. This symptom of rising damp can be tested using a Wood Moisture Meter (Product Code: N03120)
Rising Damp Treatment
In order to prevent rising damp from spreading upwards through walls, modern buildings are likely to have had an impermeable barrier or membrane, known as a damp proof course, installed during construction. Such damp proof courses can fail and older buildings may not benefit from such damp proof course in any event, leaving them vulnerable to rising damp.
In such circumstances, it is possible to reinstate the barrier to stop rising damp by installing a Chemical Damp Proof Cream. In normal circumstances, these rising damp treatments are simple to install and can be used by trade customers, builders and competent DIY enthusiasts.
In summary, the Damp Proof Cream is injected into holes drilled around the base (or mortar course) of walls suffering from rising damp. Once applied, chemicals in the damp proof cream diffuse and line the pores with a water repellent resin and block the route through which rising damp travels up the walls. It also acts to reduce the effect of the inter-molecular attraction between ground water molecules and the walls of buildings, resulting in a reduction of capillarity (the cause of rising damp).
Where rising damp has deposited salts in plasterwork on walls, this should be replaced. The reason for this is that salts in the plaster may absorb moisture from the air resulting in the appearance of damp even after installation of a damp proof course. An integral waterproofing additive should form part of the re-plastering specification and is included in our DIY Rising Damp Kit (Product Code: N00081).
Please follow this link to access our detailed installation instructions on How To Install Damp Proof Cream or call us for further information.