Resources
June 2011 Damp
Welcome to June's email bulletin. This month our topic is damp. If you have a subject that you would like us to cover in a future bulletin let us know by emailing the team at info@spabfim.org.uk.
Things to think about...
Older buildings are usually built from natural materials such as stone, brick, timber and earth (cob or wattle and daub) held together with earth or lime-based mortars. These materials are absorbent and allow moisture to penetrate the fabric and then evaporate away harmlessly when conditions are favourable. For this reason, traditional buildings are said to ‘breathe'.
In such buildings, dampness is controlled by the building's ability to allow moisture to evaporate. The wind and sun aid the evaporation of water from the external surfaces whilst internal air movement through the roof covering, walls, windows and other openings helps moisture evaporate from internal surfaces. As long as the moisture can evaporate freely, the traditional performance of the structure will function as intended and the walls of the building will remain acceptably dry.
It is therefore important to remember that many older buildings are likely to be ‘damp' to a certain degree. So in a sense, good maintenance is simply a question of managing the level of dampness to ensure that the building remains comfortable and usable. However, alterations to the fabric of the building through the years can affect its equilibrium, leading to excessive levels of dampness. If this is the case, the important point is to aim to treat the cause rather than symptoms.
The telltale indications of excessive
moisture include tide marks on walls or floors, patches of white
powdery salt
crystals on wall surfaces, green algae or mould growth and blistering
paint or
plaster. Keep an eye out for these signs
as you look around your building.
If you suspect that there might be a problem with damp consult your architect or building surveyor for independent advice rather than a remedial company with a vested interest in their own recommendations.
Be aware that injected damp-proof courses, water-repellent solutions and proprietary wall coatings can do more harm than good when inappropriately applied to old buildings.
If there is evidence of excessive dampness, it needs to be very carefully investigated to determine the cause. Damp will often be the result of a failure of rainwater goods or the build-up of ground levels around the building but it may be less straightforward. Begin by eliminating any obvious causes such as leaking pipework or a failed roof covering and work systematically through the potential contributory factors. Once the cause has been identified, appropriate remedial action can be taken.
Things to do...
The best advice is to be alert to changes in the appearance of your building that may indicate that there is a problem. However, there are some general actions you can take to help prevent excessive dampness occuring:
- Make sure that all your rainwater goods (gutters, downpipes and drains) are functioning correctly. They should carry rainwater away from the building quickly and efficiently.
- Watch out for signs of blocked or broken drains and ensure that these are fixed as soon as possible.
- Ventilate the building by opening the doors and windows on dry days. This will allow the moisture generated by people (and some heating systems) to leave the building.
- If you have them, make sure that any air bricks or ventilators are kept clear.
- Try to ensure that plant growth around the base of the walls is kept to a minimum. Trees and shrubs growing close to the walls may reduce the evaporation of moisture from the wall surface.
- Consider keeping the heating system running at a steady but low background temperature during the winter months.
If excessive dampness can be attributed to
raised ground levels the question of remedial action will require
careful
thought. Whilst it is sometimes
appropriate to lower ground levels locally around problem areas this
can destroy
archaeological evidence and needs to be tackled sensitively.
Professional advice from your architect or
surveyor will almost certainly be necessary.
Further information
- SPAB Technical Q&A 20: Rising Damp
- SPAB (1992) SPAB Technical Pamphlet 8: The Control of Damp in Old Buildings, SPAB
- Trotman P, Sanders, C and Harrison, H (2004) Understanding Dampness: Effects, Causes, Diagnosis and Remedies, BRE
- Burkinshaw, R and Parrett, M (2003) Diagnosing Damp, RICS
New advice on solar panels from English Heritage
In response to a request for specific guidance for decision-makers and advisory bodies, English Heritage has produced a new guidance note on solar panels and places of worship. Solar Electric (Photovoltaic) Panels and Slates on Listed Places of Worship sets out the policy context provided by government guidance and gives advice on how to assess a proposal with a view to minimising harm to the significance of an historic place of worship and is available on the English Heritage website.
The English Parish Church through the Centuries
A stunning new interactive DVD-ROM traces the development of some of the country's most iconic ecclesiastical buildings across the centuries. This major new digital resource combines easily accessible introductions to the latest academic research on parish churches and the influence of Christianity on literature, music, art and society with images from national and international collections. The resource explores every aspect of church and parish life, from the Anglo-Saxon period to the present day. The DVD-ROM costs £17.50 + P&P and is available from the University of York.
Need more help?
If you have any questions about maintenance or repair issues contact our Technical Helpline for advice and guidance. This service is normally available on Fridays between 9.30am and 3.30pm on 0207 456 0916. Alternatively, you can email your questions to advice@spabfim.org.uk. Copies of the SPAB's range of Technical Pamphlets and Information Sheets are available to purchase from our online bookshop.
Sara Crofts
Faith in Maintenance Project Director
Stave off decay by daily care ~ William Morris 1877
