Woodworm in London: Protecting Older Properties From Wood-Boring Beetles

London has some of the oldest and most timber-rich housing stock in the country — Victorian terraces, Edwardian semis, 1930s suburbs and post-war prefabs all share one vulnerability: wood-boring beetles, commonly called woodworm. The name is misleading — it's the larvae, not the adult beetle, that tunnel through timber for years.

Not every hole in wood means an active infestation, and not every active infestation needs chemical treatment. Here's how to read the signs, assess risk, and spend your money where it matters.

The three beetles you're most likely to find

Three species account for the vast majority of woodworm enquiries across Greater London.

Common furniture beetle (Anobium punctatum): 3–4 mm exit holes, fine talc-like dust (frass), attacks softwoods and some hardwoods. The species behind most 'woodworm' calls.
Deathwatch beetle (Xestobium rufovillosum): larger 6–7 mm holes, bun-shaped frass pellets, attacks hardwood oak and elm — common in old churches and period properties with oak beams.
House longhorn beetle (Hylotrupes bajulus): 6–10 mm oval holes, coarse frass, attacks softwood roof timbers. Rare but serious — notify your local Building Control if confirmed as it's a notifiable species.

How to tell if the infestation is active

The single most important question is whether the holes are fresh. Old damage may need no treatment at all.

Fresh exit holes have clean, sharp edges and often visible frass beneath them.
Old holes are dark, stained, and dusty inside with no recent frass.
The 'tissue test': lay a piece of white tissue paper beneath suspect holes for 2–4 weeks. Fresh frass falling onto the paper confirms active beetles.
Adult beetles emerging between May and September — if you see small beetles near windowsills in summer, it's active.

Where to check in a London house

Woodworm has favourite spots — some obvious, some hidden until a surveyor lifts floorboards.

Roof timbers and rafters — especially in unheated lofts where timber moisture content is higher.
Floorboards and joists in ground-floor rooms with poor ventilation or subfloor damp.
Older furniture — especially pieces stored in lofts, cellars, or conservatories.
Staircases — the underside of treads and risers where dust accumulates and humidity is higher.
Sheds and outbuildings — often untreated softwood that beetles colonise first.

Treatment options and when each makes sense

The right treatment depends on species, severity, and whether the timber is structurally critical.

Surface spray / brush-on insecticide: suitable for minor active infestations in furniture, floorboards and non-structural timber. Boron-based formulations are low-toxicity and effective.
Pastes and gels: applied to specific areas of heavy activity. Good for staircases and furniture where a full spray isn't practical.
Fumigation / fogging: used for severe infestations across large loft areas or multiple rooms. Requires temporary vacating.
Timber replacement: any structural joist or rafter with more than 25% cross-sectional loss should be replaced or sistered, regardless of treatment.

What treatment costs in London (2026)

Woodworm pricing is highly variable because it depends on access, the extent of the problem, and whether structural repairs are needed.

Spot treatment of a single piece of furniture: £60–£120.
Loft timber spray for a 3-bedroom house: £400–£800.
Whole-house spray including floorboards: £800–£1,800.
Structural timber replacement (per beam): £300–£1,200+ depending on access and load-bearing requirements.
Most reputable firms offer a free survey and written quote before treatment.

Frequently asked questions

Can I treat woodworm myself with shop-bought products?

For small areas of active furniture beetle in non-structural timber, yes — boron-based gels and sprays are available to homeowners. For roof timbers, structural joists, or suspected house longhorn beetle, always use a professional. The risk of missing structural damage is too high.

Does woodworm spread from room to room?

Adult beetles can fly short distances, so a loft infestation can seed new holes in timber below over several years. However, woodworm isn't 'contagious' in the way bed bugs or fleas are — each piece of timber needs the right moisture and timber type to sustain larvae.

Will treating woodworm affect my mortgage or sale?

A documented history of treated woodworm with a guarantee rarely affects sales. Untreated or active woodworm in structural timbers can trigger a retention, a reduced valuation, or a requirement for treatment as a condition of lending. A 10-year treatment guarantee is standard and reassures buyers and surveyors.