How to Treat Woodworm: The Complete UK Guide

Treating woodworm starts with one question. Is the beetle still active? Many homes only have old holes, and those need no treatment at all.

This guide walks through the steps in order. It covers how to confirm activity, which methods work, when to call a specialist and how to stop the beetle returning.

Step 1: Confirm it is active

Look for fresh, pale dust under the holes and clean, light-coloured edges. Check for live beetles in late spring and summer. Our guide to signs of woodworm lists every clue, and the post on active versus historic woodworm shows the dust test.

If you find only old, dark holes and no new dust, you can stop here. Monitor the timber for a season, because that costs nothing.

Step 2: Name the beetle

The method depends on the species, because each beetle behaves differently. Furniture beetle in open softwood is the usual case, and it responds well to spray. Death watch beetle in old oak needs a specialist, and so does house longhorn beetle in roof timbers.

Measure a hole with a ruler, since size is the best clue. Holes of 1 to 2mm point to furniture beetle, while holes of about 2 to 3mm in oak suggest death watch beetle. The species guide has the rest.

Step 3: Fix the damp

Beetles prefer damp timber. If a leak or poor ventilation feeds the problem, treatment alone will not last. Clear air bricks, mend gutters and dry out the area first.

Step 4: Choose a method

Four methods cover most cases, although the right mix depends on your timber:

• Spray. A water-based insecticide spray suits open, sound softwood.
• Paste or gel. Boron paste reaches thick or damp timber.
• Fogging or fumigation. Fumigation suits widespread cases.
• Repair. Timber repair restores strength where the beetle has done harm.

DIY or professional?

For a small item, such as a chair or a shelf, a shop product can work. Wear gloves and a mask, follow the label and treat the whole piece, including the underside.

For floors, joists and roof timbers, a professional survey is wiser. A DIY fluid may not reach deep enough, and you cannot tell if the structure is weak. Our post on DIY versus professional treatment weighs both routes.

What it costs

Prices vary with the area, access and method. Published UK guides put a single room at about £300 to £500 and a whole house at £800 to £1,000 or more. The cost guide lists each source.

Safety

Always follow the product label. Keep children and pets out of the treated area until it is dry and ventilated. Permethrin is toxic to cats and fish, so take extra care with them, and cover fish tanks.

Stop it coming back

After treatment, keep the timber dry and the voids ventilated. Seal bare wood with paint or varnish, and check the loft and floors each spring. Read how long treatment lasts to know what to expect.

Ready for a firm answer? Request a survey and compare written quotes.

Homes differ by city, so local advice helps. Our pages on woodworm treatment in Nottingham and woodworm treatment in Plymouth explain the usual problems.

To go deeper, read about the spray treatment and the boron paste treatment, because the right method depends on the beetle.