Treating woodworm yourself

Check it is active first

Many woodworm holes are old, and treating dead beetles wastes money. Look for fresh holes with sharp edges and pale dust below them, ideally between June and August. Our guide to identifying woodworm shows the difference.

If the holes are dark, there is no fresh dust and the wood is solid, there is probably nothing to treat.

Small areas and furniture

For furniture, a shed or an accessible patch of timber, a permethrin-based woodworm fluid is a sensible DIY choice. Apply two coats, 24 hours apart, to bare, dry wood. DIY sprays cost about £20 to £60.

Read the product label and follow it exactly: wear gloves, work in a ventilated space and keep children and pets away until it dries. Treating a small item outdoors is easier than treating a room.

Preparing the job

Brush away old dust so you can spot fresh dust later, and test the product on a hidden patch first if the wood is varnished or valuable. Treat bare wood: old polish or paint stops fluid soaking in. Work on one item at a time and write the date on the back, so that you know when to check again.

Treating furniture outdoors on a dry day is safer and easier than spraying a whole room. Keep treated pieces out of use until they are dry.

Fix the damp

Damp timber is what makes infestation likely. Fix leaks, clear gutters and ventilate the space. Treatment on timber that stays damp is likely to fail. See damp proofing if the moisture has a structural cause.

What DIY will not do

A DIY fluid cannot tell you whether the beetles are active, and it may not reach deep inside thick timber. It also comes with no guarantee, which matters when you sell or remortgage.

If a surveyor has already said the timber is inactive, you do not need to treat it. If a buyer's lender has asked for a report or guarantee, go straight to a specialist.

When DIY is the wrong choice

Do not treat any of these yourself:

• structural joists, roof timbers or floors
• a loft where bats may roost, because all bats and roosts are protected and treating a roof without checking can be an offence
• anything a buyer's lender wants a guarantee for, since DIY comes with none
• widespread infestation across several rooms

A PCA member can offer an insurance-backed guarantee that continues if the contractor stops trading.

After treatment

Beetles in treated timber die over the following season, but emergence holes can continue for up to a year. Do not panic if new holes appear. Keep the timber dry, and check for fresh dust the next summer. If dust keeps appearing, book a woodworm survey. Prices for professional work are on the cost page.