Guide to woodworm problems

Page 1: What is woodworm?
Page 2: What damage can woodworm cause?
Page 3: What does it cost?

Anna Heywood - Writer

How much damage can woodworm cause?

The amount of harm caused by woodworm will depend on the species of beetle and the type of wood.

Common Furniture Beetle

Attacks softwood (conifer) and the sapwood of European hardwoods. Rarely causes structural weakening although tunnelling along the grain of the wood can potentially cause extensive collapse.

House Longhorn Beetle

Only attacks the sapwood of softwood timbers. As softwood is often used in roof timbers, infestation can often result in severe structural weakening. The good news is that this species is now rare in the UK.

Powderpost Beetle

Causes damage to wide-pored hardwood with a high starch content, such as ash, elm and oak. Older timbers (over 15 years old) don't provide a suitable environment for this species. Tunnels along the grain and can cause severe damage, often infesting block or parquet flooring.

Deathwatch Beetle

Prefers European hardwoods, especially oak, ash and chestnut that has been "softened" by partial decay. The larvae tend to tunnel towards the centre of the timber, so that damage may be more extensive than is apparent from the exterior. In the UK, this species is concentrated chiefly in southern/central England, and is virtually absent in Scotland.

What treatments are available?

So you've found evidence of woodworm. Before deciding on a treatment, you should:

  • Identify the species.
  • Determine whether the infestation is still active.
  • Employ a timber specialist or qualified surveyor to determine which timbers have been structurally weakened and need replacing.

Timber that has been structurally weakened will have to be removed and replaced with pre-treated timber. Other affected woodwork will then need to be treated. Small-scale treatment can easily be carried out as a DIY job, but professional advice is recommended for the treatment of larger scale infestations and certainly for removal and replacement of large timbers.

Methods of treatment include:

  • Surface application of pesticides.
  • Freezing only suitable for items of furniture infested with woodworm.
  • Fumigation usually appropriate for Deathwatch Beetle infestation in large structural hardwoods. The adult beetles are effectively "smoked out" during the annual flight season.

Environmental concerns

Many of the most effective insecticides can only be obtained by certified professionals. Some are not advisable due to their toxicity and potentially damaging effect on human health and the environment. While it's tempting to opt for a blanket treatment, this may not be the greenest choice. It's worth bearing in mind, for example, that treated timber is considered toxic waste at the end of its lifespan and must be disposed of accordingly.

Between 50,000 and 150,000 remedial timber treatments are carried out in British homes each year, many of which may be unnecessary. Overuse of toxic chemicals in residential settings puts occupants at risk so it's preferable to avoid unneeded repeat treatments. You can contact Property Guarantee Administration, a company which can identify active timber treatment chemicals from a small timber sample which you send them. A laboratory analysis and report costs 95.00 plus VAT per sample. This could eliminate the unnecessary use of pesticides in your home as well as saving you a substantial sum of money if further treatment proves unnecessary.

A safe but effective treatment is borax, a compound of boron also known as sodium borate. This is available as a crystalline powder, which is dissolved as a 15% solution in water and applied to the affected timber. There are no health hazards associated with this treatment, and borax will inhibit fungal growth as well as killing woodworm.

 
 


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