Damp Proofing
Damp Proofing in the UK
Introduction
Rising damp is a common problem in older properties either because no damp proof course (DPC) was provided at the time of building, or because a physical membrane has failed or been 'bridged'. It may be possible to solve the problem by reducing ground levels but this is not always feasible and, in the majority of cases, the provision of a remedial DPC is a cost effective and minimum-disturbance option.
AAWU members can offer a wide range of systems to deal with Rising Damp; from Electro-osmosis, which works by reversing the background 'static charge' in damp walls, to chemical DPCs such as Injection Mortar (cementitious grout), Silicone microemulsions and, most recently, silicone cream injection (non-pressure process).
All the chemical dpc systems used by AAWU members are suitable for use in accordance with BS 6576:2005, are manufactured under a BS EN ISO 9001:2000 QA scheme and are independently approved by the BBA (British Board of Agrement).
Damp Proofing
These brief descriptions of common damp problems may help you to ascertain whether you have a problem which requires further attention. However, the list is not exhaustive so we recommend you contact your nearest AAWU member for clarification.
All our members are experts in the detection and diagnosis of damp and associated defects. Their reports may include recommendations for treatment (where necessary) using only the highest quality materials.
Damp-Proofing Diagnosis Guide
| Symptoms | Time and Weather | Cause -> Treatment |
|---|---|---|
| Patches on external walls usually on lower exposed elevation | After rain | Cause: Penetrating Damp, (porous masonry) Treatment: Re-pointing, Exterior water repellent/render, Internal re-plastering |
| As above, also upper elevations, but related to external defects (pointing, chimneys, flashing, windows, rainwater goods etc.) | After rain | Cause: Penetrating Damp (external faults) Treatment: Various structural repairs |
| Running water or damp patches below ground level | Dependent on water table or rainwater saturation of soil | Cause: Penetrating Damp (basement) Treatment: Various 'tanking systems' |
| Patches or continuous bands in ground floor rooms extending up from floor level |
Usually persistent, prolonged damp | Cause: Rising Damp Treatment: Various remedial DPC systems |
| Damp patches showing on plaster as an after-effect of rising damp. Occasionally, damp patches on chimney breast. | Before and possibly during rain (typically 'comes and goes') | Cause: Hygroscopic damp (salts) Treatment: re-plastering systems |
| Patches on external walls, often in corners, within cupboards. Moulds disfiguring surface. Especially prevalent in or near kitchens and bathrooms. | Usually in cold weather | Cause: Condensation Treatment: Improve ventilation, and/or heating (or insulate). Consider mould control system where other measures not feasible |
*Detailed recommendation should always be sought from an AAWU member - these notes are for guidance only