5 common causes of timber decay

Timber Roof Frame

Wood rot and insect attack are among the most common problems encountered with traditional buildings. The team at Hutton + Rostron are market-leading experts in the investigation and repair of timber decay. In this blog, we take a look at five of the worst offenders and how to approach remedial action.

Dry Rot

The dry rot fungus Serpula lacrymans destroys softwood timber and, occasionally, hardwood too. Conditions for it to thrive include a relative humidity of 95% and a moisture content in the timber above 20%. In its final stages, dry rot has a distinctive fruiting body that is orange in colour with white edges and is typically plate-shaped. The greyish-white threads known as mycelium enable the dry rot to spread across other materials including brickwork. Dry rot-affected timber is usually light brown, dry and brittle, with characteristic cuboidal cracking.

Wet Rot

Wet rot can cause timber darkening (brown rot) or timber bleaching (white rot). The most common wet rot fungus is Coniophora puteana aka cellar fungus. In order to grow, wet rot requires persistently damp conditions with a moisture content of around 50-60%. Wet rot is responsible for nearly 90% of timber decay in buildings. Even though some fungi produce fruiting bodies similar to dry rot, the main evidence of wet rot is usually found in the form of black/brown strands. Cuboidal cracking can also occur but this is shallower than with dry rot.

Furniture Beetle

The common furniture beetle Anobium punctatum, better known as woodworm, prefers the sapwood of softwoods and hardwoods, but rot-affected heartwood can also be vulnerable. Damp areas including timber ground floors and poorly ventilated roof voids are most at risk. The furniture beetle is most active between March and August particularly during warm weather, leaving behind boreholes of 1-2mm in diameter and gritty, cream-coloured bore dust.

Powder-Post Beetle

This beetle – Lyctus brunneus – only attacks the sapwood of hardwoods including oak, ash, elm and chestnut and it prefers younger wood. Softwoods as well as 15+-year-old-timber are immune to damage from this wood-boring insect. The powder-post beetle is active throughout the year, particularly in heated buildings. Boreholes of approx. 1.5mm is a tell-tale sign, as is very fine bore dust resembling powder.

Death Watch Beetle

A death watch beetle (Xestobium rufovillusom) infestation is most likely to occur among large-sectioned hardwood timbers such as oak or elm, in areas where there is already some rot present, meaning older properties are most at risk. For an attack to become established, damp conditions are required, however, a slower pace of attack may continue even if the wood dries out. This beetle is most active during springtime, emerging through 3mm bore holes and leaving behind coarse bore dust.

If your home or business premises are affected by timber decay, H+R should be your first port of call. With over 30 years experience of surveying older and historic buildings, we can provide valuable advice and effective treatment options to remedy and control timber decay, and other types of insect decay and fungal decay in buildings including dry rot.

How not to deal with the problem

Sadly, many companies will suggest remedial treatments that can result in the loss of original decorative finishes, floors and ceilings. What’s more, the chemical treatment of infestations is often not only expensive and inconvenient but may also be hazardous to human and environmental health.

Inappropriate repairs and treatments tend to come about as a result of a lack of understanding of the significance and structural implications of decay and, therefore, the misdiagnosis of fungal decay and insect attack. Some contractors are keen to provide a guaranteed-backed one-touch solution that sounds commercially attractive to the client but may lead to specifying more work than is necessary in order to minimise the risks of any claims being made.

Why choose H+R?

At H+R, we pride ourselves on the use of environmentally friendly remedial solutions to effectively combat insect attacks and fungal decay in timber. Once treatment is complete, we can employ building monitoring systems to help control acute problems while offering long-term protection for your building.

  • Non-invasive timber decay survey inspection, using precision measurement techniques and equipment as well as our specially trained Rothound dry rot sniffer dogs
  • Timber decay survey report, with detailed information about the extent and causes of decay as well as recommendations for environmental control measures
  • The post-treatment monitoring programme, serves as a valuable building maintenance and management tool

As experts in dealing with timber decay in historic buildings, Hutton + Rostron will always recommend that the problem should be prevented and controlled by maintenance and appropriate repair to ensure invasive repairs and treatments are unnecessary.

For more information about our timber surveys or any other type of building investigation services offered by H+R, please get in touch.

Author: Carissa
Published on Last updated 27th March 2024

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