Woodworm Treatment in North London
Flight holes in floorboards don't always mean live woodworm — and live woodworm doesn't always mean drama. We establish what you actually have, then treat exactly that.
How do you know if woodworm is active? Woodworm is the larvae of wood-boring beetles — most commonly the common furniture beetle, Anobium punctatum — tunnelling through timber for years before emerging through the familiar 1–2mm flight holes. Activity is confirmed by fresh, light-coloured frass (bore dust) beneath holes, pale clean-edged new holes, and adult beetles emerging May–September; old dark holes alone often indicate a historic, dead infestation needing no treatment. Active infestations are treated with professional insecticidal sprays or gels to affected timber, with severely weakened members repaired or replaced — typically £400–£1,200 for treatment in a North London house.
Understanding the problem
Almost every Victorian and Edwardian property in North London has some flight holes somewhere — the beetles have had a century of opportunity. The meaningful questions are: is it active, which species is it, and has structural timber lost strength? Common furniture beetle in a floorboard is routine; deathwatch beetle in oak, or heavy infestation in damp structural softwood, is a different conversation. And because the larvae prefer damp timber, woodworm often flags a moisture problem worth fixing in its own right.
Blanket 'preventative' spraying of every timber in the house — a staple of bad surveys — wastes money and chemicals. Treatment belongs where activity is confirmed.
Signs and symptoms
- Fresh flight holes with pale, clean edges (1–2mm for common furniture beetle)
- Gritty light-coloured frass beneath or in holes
- Adult beetles or dead beetles on sills, May–September
- Weak, crumbling floorboard edges; boards breaking at fixings
- Tunnelling visible in cut or broken timber
- Larvae found during floor or roof works
What it might be
- Common furniture beetle — the usual suspect in softwood floors, joists, roof timbers
- Deathwatch beetle — older hardwoods (oak), often with existing decay; rarer, more serious
- Wood-boring weevils — only in already-decaying damp timber; fix the damp
- Elevated timber moisture (damp subfloors, roofs) favouring all of the above
Getting the diagnosis right
A woodworm survey identifies the species from hole size, frass and timber type; establishes activity (fresh frass tests, hole condition, seasonal evidence); probes for structural weakening at bearings and heavily-holed sections; and moisture-checks the environment, since infestation concentrating in one area usually maps to damp — a subfloor without ventilation, a leaking roof corner. The report specifies treatment areas only where justified, and repairs where strength is compromised.
Treatment
- Insecticidal treatment — affected timber cleaned and sprayed/brushed with professional boron- or permethrin-based preservatives, penetrating where larvae feed; injection gels for thick sections and deathwatch cases.
- Structural repairs — weakened boards, joist sections and bearings replaced or spliced with pre-treated timber.
- Moisture correction — the underlying damp addressed: subfloor ventilation, roof or gutter repairs, damp treatment — drier timber resists re-infestation.
- Access & reinstatement — boards lifted and refitted; furniture treatment advice where infested pieces are the source.
- Verification — activity indicators rechecked the following emergence season for significant infestations.
What does it cost in North London?
| Item | Indicative range |
|---|---|
| Woodworm survey | £260 – £400 |
| Localised treatment (one floor/void) | £400 – £700 |
| Whole-property treatment | £700 – £1,200 |
| Structural repairs | £300 – £1,500+ per area |
If a 'free survey' recommends whole-house spraying without evidence of activity, get a second opinion before paying. Figures are indicative for North London (2026) and vary with property, access and scope — written quotations follow a survey. See the North London Damp Cost Guide or try the Timber Treatment Cost Estimator.
Our process
Tell us the problem
Call or use the contact form — describe what you're seeing and where. Photos help.
Survey & diagnosis
An independent qualified surveyor inspects the property and identifies the true cause, with a written report.
Clear written quote
You receive a costed scope for exactly what the property needs — no more, no less.
Treatment & verification
Works are carried out by vetted independent specialists, with guarantees where applicable and verification that the fix worked.
Frequently asked questions
Not by themselves — most period properties carry historic, inactive holes. Treatment is warranted when activity is confirmed: fresh pale frass, clean new holes, or beetles in season. A survey distinguishes live infestation from old history.
In North London, £400–£700 for localised treatment of one floor or roof void, £700–£1,200 for whole-property treatment where genuinely justified, plus any structural repairs. Surveys run £260–£400.
Adult common furniture beetles emerge May–September, which is when fresh holes, frass and beetles appear. Surveys can confirm activity year-round from frass and hole evidence, but emergence season gives the clearest picture.
Heavy, long-running infestation can meaningfully weaken boards and joists, especially where damp accelerated it — that's why surveys probe bearings and edges. Typical light infestations are a treatment matter, not a structural one.
Often there's a link: larvae develop faster in timber above ~12% moisture, so concentrated activity frequently maps to a damp subfloor, roof leak or condensation zone. Treating the moisture is part of preventing re-infestation.
Worried about damp, mould or a wet basement?
Speak to us today or book a survey — we'll arrange the right independent specialist for your property.