Do's and Don'ts of Timber & Damp Treatment
By Graham Coleman at www.buildingpreservation.com
- Do regularly check building for water leaks
from guttering, also check for defects in pointing,
the roof and other structures (e.g. lead flashing)
which could allow water ingress. Remember dry wood
doesn't rot. Make sure therefore the building is regularly
inspected and maintained for any likely signs of water
penetration. Internal plumbing or wet heating systems
that leak are also a source of water that can lead
to rot, etc.
- Do be aware that if timbers remain persistently damp or are very slow drying they
will be at risk of rot developing. Where such dampness is encountered and it is not cost-effective
to remove then some form of suitable targeted preservative treatment may be used to minimise
the risk of rot developing. It is also very important to discover why and where the moisture
is coming from and considering undertaking any building works to eradicate the problem now
or in the future.
- Do be aware that certain levels of dampness in older properties may be acceptable.
However, where this is deemed so any timber in contact with that dampness should be protected
from it to prevent the risk of rot.
- Do evaluate any dampness problems carefully. For example if the dampness persists
through the warmer months of the year (April-October) then it is unlikely to be condensation.
Look for other sources including rising damp, penetrating damp, plumbing leaks, etc.
- Do use materials that are sympathetic with those currently forming the fabric
of the property. For example replace defective old lime mortar pointing with lime based
materials and not with cement based materials. But -
- Do understand that replacing salt contaminated original old plasters with similar
materials could lead to similar decorative problems in the longer term. Discuss any such
problems with a specialist conservationist/specialist surveyor.
- Do ensure adequate ventilation during the colder months of the year. Remove water
by extraction, eg, extractor fans, from areas of high moisture production, eg, kitchen and
bathroom. Try to maintain at least a low level of background heat to most rooms.
- Do ensure that earth or other materials do not pile up against walls above the
natural internal floor level. Ideally ground level should be at least 150mm/6" below internal
floor level. To achieve this it is sometimes necessary to create drainage channels around
- Do be aware that some properties are in areas of high ground water levels and
will be more prone to dampness. This can sometimes be tackled by diverting ground water
away from or around the building by land drains. Such a solution can often be used uphill
of a property built into a slope.
- Do ensure rainwater can flow freely away from the base of the building. If downpipes
run straight into ground or underground gullies with no access, consider installation of
rodding eyes to facilitate periodic clearing.
- Do be aware that heavy plant growth on the face of buildings can lead to long-term
- Do ensure that if you are having a period property surveyed for purchase the
individual employed to undertake the survey is familiar with the contents of the RICS Red
book concerning the valuing of historic buildings for mortgage purposes. It is preferable
that your surveyor has a diploma in Building Conservation and/or is accredited in Building
- Do use a specialist surveyor if dampness persists. Use a member of the BWPDA
who has the nationally recognised CSRT qualification (or CRDS/CTIS qualifications), provided
the surveyor is familiar with your type of property and construction. Use a company that
charges for surveys and always get competitive quotes. Thoroughly read all reports. The
surveyor should not have a vested interest in his/her recommendations.
- Do ensure that the source or cause of dampness has been properly identified and
dealt with before tackling other repairs.
- Do be aware most wood boring insects cannot be eradicated simply by ventilation.
- Do be aware not all wood boring insect activity needs treatment, eg, old damage,
innocuous insects, forest insects.
- Do be aware that randomly applied surface treatment is usually ineffective in
eradicating active infestation. Many wood boring insects will survive in hidden or difficult
to reach areas, this requires a targeted approach.
- Do evaluate the structural integrity of infected/rotted timbers prior to any
treatment that is deemed necessary. Only replace timbers that have lost their structural
integrity. Consider the form of repair, as simple replacement is often only one of several
- Floor bricks, pamments, and flagstones were often laid directly on to earth, chalk or lime in older properties which allows ground moisture to slowly evaporate. Do not automatically assume that such floors need to be dug out and replaced with a dpc and concrete. If you do not have a damp floor leave it or simply remove lino and/or carpet to allow the floor to dry out before considering any actions. Also ensure floors laid on earth, chalk or lime are not sealed with a synthetic sealant and consider traditional alternatives such as lime water, turpentine and beeswax or linseed oil. The joints between the flooring material should be left untouched.
Although we have taken great care to ensure that our information and advice is correct, we cannot accept any responsibility for any loss or damage incurred arising from the use of the information published on our web site. Before committing yourself to any expenditure, you are advised to check any details and costs beforehand.
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