Guide to timber preservation
Guide to timber preservation
|Page 1: Common timber problems
Page 2: Secondary treatments
Page 3: Locating a specialist
Anna Heywood - Writer
Why is timber preservation important?
Timber has been used as a structural material for millennia and is in many ways ideal for the job. It can be described as strong, beautiful and sustainable – basically, wood is good! However, wood-rotting fungi and the wood-boring larvae of certain insects (also known as woodworm) feed by breaking down wood cells and, if left unchecked, ultimately destroy the timber in your home. Fungi and woodworm consequently threaten the structural integrity of your home, leading to substantial financial costs and potential danger for inhabitants.
Common timber problems
A new-build house should be constructed with timber preservation in mind. However, most of us live in houses that we haven't built and inherit timber problems along with the property. The three most common problems likely to affect timber are woodworm, dry rot and wet rot.
Click here for advice on Control. This guide will focus on:
Dry rot, which refers to a particular species of fungi - Serpula lacrymans – and Wet rot, which is a more general term, encompassing a range of fungi.
How can I identify wood-rotting fungi?
Dry rot breaks down wood cellulose and causes timber to become dry and powdery. Serpula lacrymans grows in strands, digesting adjacent timber until it "fruits" and discharges fungal spores. Fugenex produce a sensor which detects the presence of incipient dry rot, and costs about £7.50 . It's a useful DIY test and only involves drilling a small hole in the timber - if the sensor changes colour you know there is a dry rot problem and you can call in the experts!
Wet rot is more easily identified than dry rot, quite simply because affected timber will feel damp to the touch. With painted timber, the area may look and feel sound superficially, but the underlying timber may be rotten – try pushing a knife into the timber, you should feel resistance after a few millimetres. Timber affected by wet rot feels spongy and looks darker than surrounding wood. When dried, timber affected by wet rot cracks and crumbles into fine particles.
Rot will only affect timber that is physically damp. Dry rot requires a modest moisture content of 20%, while wet rot needs an elevated level of moisture (28-30%) to become established. Thereafter it can persist in timber which has a minimum moisture content of 20%. You may wish to employ a specialist, but here are three DIY steps it's worth trying first:
STEP 1 - remove the source of moisture
The most common reasons for damp timber are leaking appliances, poorly sealed sinks/baths, leaking roofs and overflowing drainpipes and rising damp.
STEP 2 – promote rapid drying conditions If you can find and fix the source of the water and allow timber to dry out properly, you can control and ultimately eradicate the rot. To speed up drying, ensure good ventilation and increase the ambient temperature.
STEP 3 – remove and replace affected timber Badly affected timber should be removed and replaced. Sections of rotten timber can be replaced with epoxy resin. This is especially appropriate for repairs to valuable/historical beams, as work can be done in-situ - see below for further sources of advice.
Next: Secondary treatments >>