Rising damp in walls - diagnosis and treatment (DG 245)
BRE (Building Research Establishment) is an independent, research-based consultancy, testing and training organisation, operating in the built environment and associated industries.
On 12 October 2007, BRE published Rising damp in walls - diagnosis and treatment (DG 245 revised edition), written by Peter Trotman.
Excess moisture is a common problem in buildings, and may be apparent from; damp patches, mould growth, mildew, salts, staining, ‘tide marks', blistering paint, bulging plaster and so on.
Rising damp is caused by capillary action drawing moisture up through porous elements of a building’s fabric. DG 245 considers the causes of rising damp in walls and how to remedy it if found.
Porous walls which stand in water or saturated soil without a damp proof course (dpc) can have rising damp to a height of more than 1m, with the height depending on:
- The rate of evaporation from the wall.
- The porosity of the wall.
- The salt content of the wall and soil.
- The groundwater height and saturation.
- Heating in the building.
Some accumulation of salts can occur in the walls of old buildings even when they do not have a damp problem, so high readings from a moisture meter alone are not conclusive. Appendix A of the 12-page digest describes how to drill samples from a wall in to test for moisture content and hygroscopicity, and the interpretation of moisture gradient profiles.
If a building has a physical damp-proof course (DPC), it is unlikely that it has failed, as most dpc materials have a long life, however, defects such as mortar droppings in a cavity wall, may make a dpc ineffective by bridging it and allowing moisture to pass up through the wall. This and other mechanisms by which an existing dpc might be bridged are discussed.
If it is necessary to provide a new moisture barrier, the digest explains methods such as; inserting a membrane or using chemical injection. The repair of plaster damaged by damp is also discussed.
The content of the digest includes:
- Mechanism of rising damp.
- Diagnosis.
- Determining the source of the dampness.
- Treatment.
- Replastering.
- Dry lining.
- Further reading.
- Appendix: The sampling method.
[edit] Related articles on Designing Buildings Wiki
- Assessing moisture in porous building materials.
- BRE articles on Designing Buildings Wiki.
- Building Research Establishment.
- Carbide meter.
- Condensation.
- Damp.
- Damp-proof course.
- Damp proof membrane.
- Defects in brickwork.
- Dew point.
- Diagnosing the causes of dampness (GR 5 revised).
- Does damp proofing work?
- Efflorescence.
- Electrical resistance meters.
- Interstitial condensation.
- Mould growth.
- Penetrating damp.
- Psychometric chart.
- Rising damp.
- Sling psychrometer.
- Spalling.
- Tanking.
- Treating brickwork with sealant or water repellent.
- Understanding dampness.
[edit] External references
Featured articles and news
International Electrician Day, 10 June 2025
Celebrating the role of electrical engineers from André-Marie Amperè, today and for the future.
New guide for clients launched at Houses of Parliament
'There has never been a more important time for clients to step up and ...ask the right questions'
The impact of recycled slate tiles
Innovation across the decades.
EPC changes for existing buildings
Changes and their context as the new RdSAP methodology comes into use from 15 June.
Skills England publishes Sector skills needs assessments
Priority areas relating to the built environment highlighted and described in brief.
BSRIA HVAC Market Watch - May 2025 Edition
Heat Pump Market Outlook: Policy, Performance & Refrigerant Trends for 2025–2028.
Committing to EDI in construction with CIOB
Built Environment professional bodies deepen commitment to EDI with two new signatories: CIAT and CICES.
Government Grenfell progress report at a glance
Line by line recomendation overview, with links to more details.
An engaging and lively review of his professional life.
Sustainable heating for listed buildings
A problem that needs to be approached intelligently.
50th Golden anniversary ECA Edmundson apprentice award
Deadline for entries has been extended to Friday 27 June, so don't miss out!
CIAT at the London Festival of Architecture
Designing for Everyone: Breaking Barriers in Inclusive Architecture.
Mixed reactions to apprenticeship and skills reform 2025
A 'welcome shift' for some and a 'backwards step' for others.
Licensing construction in the UK
As the latest report and proposal to licence builders reaches Parliament.
Building Safety Alliance golden thread guidance
Extensive excel checklist of information with guidance document freely accessible.
Fair Payment Code and other payment initiatives
For fair and late payments, need to work together to add value.
Pre-planning delivery programmes and delay penalties
Proposed for housebuilders in government reform: Speeding Up Build Out.
High street health: converting a building for healthcare uses
The benefits of health centres acting as new anchor sites in the high street.
Comments