Resources
September 2008
Welcome to September's Faith in Maintenance monthly email bulletin. Every month we will be sending you a short reminder of some of the things that you might do to make sure that your place of worship is in tiptop condition.
This month we are going to tackle the
thorny issue of damp. Traditional
buildings are usually built of 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.
To aid this natural process, traditional
buildings were carefully detailed to encourage the shedding of water from their
surfaces. Features such as deep
overhanging eaves, protective lime renders, lead flashings, wide gutters and
sturdy plinths at ground level were used to protect the wall surfaces as much
as possible. If such details are altered
or unable to function the building might be put at risk. A common example is excessive dampness caused
by gutters or downpipes becoming blocked.
You might also encounter signs of dampness if the external ground levels have risen above the internal floor level because of burials in the churchyard over many centuries.
Things to look for:
The first point to consider is that all old buildings will be damp to a certain degree. They are designed to accept moisture and to allow this moisture to evaporate when the conditions are right.
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.
Look out for these signs as you walk around your building. If you suspect that there might be a problem with damp consult your architect or 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 do
more harm than good when inappropriately applied to old buildings.
If there is a possibility of damp, 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 condition of the fabric that may indicate that there is a problem. However, there are some general actions you can take to help manage the levels of damp in your building:
- Make sure that all rainwater goods are functioning correctly and carrying the 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 humans (and some heating systems) to leave the building.
- 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 will 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 any 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 in the soil and needs to be tackled sensitively. Professional advice from your architect or surveyor and from an archaeologist will almost certainly be necessary.
Further Reading
- 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
- SPAB Technical Q&A Number 20 - Rising Damp
Further
help and advice
If you are unsure about how to look after your place of worship or have any questions about issues related to maintenance and repair you can contact David John, our Technical Advisor, on the Faith in Maintenance Technical Advice Line. This service is normally available on Fridays between 9.30am and 3.30pm on 0207 456 0916.
You can also visit our online bookshop, which sells the SPAB's range of Technical Pamphlets and Information Sheets as well as a selection of related conservation and repair titles and our newly published Good Maintenance Guide.
Remember that you can also log in to the Faith in Maintenance Forum to find our latest tips and suggestions. Share your own ideas and experiences by registering at www.spabfim.org.uk/forum/index.php.
News!
Training DVD funding secured! The Faith in Maintenance
team are delighted to announce that they have received funding for their training DVD
from the Pilgrim Trust and the Dulverton Trust
and work is now under way. We are
hopeful that the DVD will be ready for distribution by Spring 2009 and
that some of the footage will be made available on the website too! As with our training courses, the DVD will
focus on the idea of preventative maintenance and will help volunteers
understand why buildings decay and how the problems caused by broken gutters
and leaking roofs can be avoided.
At present, we are able to provide training for around 1,200 volunteers every year but we hope that a professionally produced DVD will allow us to make our advice and guidance available to a much wider audience, extending the benefits of the Faith in Maintenance project enormously.
We hope that you have found this email bulletin useful. If you have any comments or suggestions on how we may improve this service please do get in touch with us using bulletin@spabfim.org.uk.
Sara Crofts Faith in Maintenance Project Director
Stave off decay by daily care ~ William Morris 1877
