Damp (structural) - Rising Damp - Treatment of Rising Damp

Treatment of Rising Damp

In many cases, damp is caused by "bridging" of a damp-proof course that is otherwise working effectively. For example a flower bed next to an affected wall might result in soil being piled up against the wall above the level of the DPC. In this example, moisture from the ground would be able to ingress through the wall from the soil. Such a damp problem could be rectified by simply lowering the flower bed to below DPC level.

Where a rising damp problem is caused by a lack of a damp-proof course (common in buildings over approximately 100 years old) or by a failed damp-proof course (comparatively rare) there are a wide range of possible solutions available. These include:

• Replacement physical damp proof course
• Injection of a liquid or cream chemical damp proof course (DPC Injection)
• Porous tubes
• Electrical-osmotic systems
• Land drainage

BRE Digest 245 suggests that with the exception of replacement physical DPCs, only methods of treatment with third party accreditation (E.g. British Board of Agreement Certificate) should be considered. It then goes on to state that the only method of currently satisfying this requirement is DPC injection (liquid or cream) and that "this is the only method which BRE considers suitable where insertion of a physical DPC is not possible." The Royal Institute of Chartered Surveryors (RICS) publication "Remedying Damp" is more cautious about reliance on third party accredititation, casting doubt upon the validity of the test methods employed, arguing that trials are usually conducted using "specially built masonry panels - which do not match up in many respects to walls found in real properties," and that "if a DPC were proved to not work in a specially built masonry panel, this would be the more significant result." The MOAT No 39 test employed by the British Board of Agrément (BBA) in the UK is dismissed as "quite a clever test idea but in the author's opinion not actually replicating a real wall." Furthermore, the point is made that "BBA testing is paid for by manufacturers, and the results are not thought to be publicly available."

In his book, Dampness in Buildings, Alan Oliver refers to research carried out in Belgium regarding the effectiveness of different types of rising damp treatments:

"In Belgium, at the Centre Scientifique et Technique de la Construction (CTSC, 1985), research was carried out on the effectiveness of the main retrofit DPCs found in Europe. It was generally found that physical DPCs performed best, followed by the various chemical DPCs, with electro osmosis and atmospheric syphons being the least effective."