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Woodworm killer buying guide: what to check before you buy

Updated: October 2026

You have found small holes in a chair, or in timber beside a greenhouse, and amazon.co.uk is ready to sort the results by stars. This woodworm killer buying guide decides whether any bottle belongs in the basket. Fresh dust on a piece you can turn over is a different job from dark holes in a joist, and an amateur fluid is not a professional-only biocide. Check the attack, the user category, and the use line before the brand. The [woodworm killer comparison](/hub/raised-beds-greenhouses-and-compost/woodworm-killer) then sets the bottles side by side. Prices and review counts are amazon.co.uk extracts from 16 October 2026, not a laboratory test, and a qualifying purchase can earn us a commission.

You have found small holes in a chair, or in timber beside a greenhouse, and amazon.co.uk is ready to sort the results by stars. This woodworm killer buying guide decides whether any bottle belongs in the basket.

Our top picks

Rentokil Rentokil PWT25 woodworm treatment fluid 250 ml

Best overall

Rentokil Rentokil PWT25 woodworm treatment fluid 250 ml
8.5/10about £9.59
View offer
Lignum Lignum woodworm killer 1 litre

Rank 2

Lignum Lignum woodworm killer 1 litre
8.7/10about £10.97
View offer
Soluguard Soluguard woodworm treatment, 2 x 500 ml

Rank 3

Soluguard Soluguard woodworm treatment, 2 x 500 ml
9.0/10about £15.98
View offer
On this page
  1. 1.Check the holes before the brand
  2. 2.Read the user category and the use line
  3. 3.Size, rate, and what the listing leaves blank
  4. 4.Pets, drying, and roofs

Check the holes before the brand

The British Pest Control Association describes common furniture beetle holes at about 1–2 mm, often with fine pale frass. The Property Care Association says a dead attack does not justify treatment. Dark holes with no fresh dust are the pattern the Society for the Protection of Ancient Buildings sees when sound old timber is sprayed because a house has changed hands. A chair you can isolate can be an amateur job if the label allows it. A joist you cannot see all round, or timber holding a floor, a stair, or a roof, is not, because fluid does not rebuild crumbled wood. How to tell fresh frass from old dust is on is woodworm active or old. If the attack is finished, stop before you compare brands.

Read the user category and the use line

The Health and Safety Executive allows the public to use only biocides authorised for the general public, in the original container, at the rate on the label. A professional-only woodworm killer is not a legal upgrade for a weekend. If the user category is missing, or the authorisation number does not match the current HSE list, leave the bottle. An amazon.co.uk title is not the label. The use lines in this extract do not agree. Both Lignum tins state interior use. Zero In names internal furniture and living areas. Rentokil’s 250 ml listing says indoors and outdoors, which is wider than a spare-room chair and still the wrong tool for a raised bed in soil.
Rentokil Rentokil PWT25 woodworm treatment fluid 250 ml

Testsieger

Rentokil Rentokil PWT25 woodworm treatment fluid 250 ml
8.5/10about £9.59
View offer

Size, rate, and what the listing leaves blank

Litres mean nothing without a rate. Barrettine’s published 500 ml label, separate from the amazon.co.uk bullets, states about 300 ml per square metre to eradicate and about 200 ml per square metre to prevent, on internal timbers. At the higher figure, 500 ml covers well under two square metres once the underside is included. Where this extract prints no rate, the tin governs. A lower price per litre does not fill that gap. On 16 October 2026 a small job sat under about £13, such as Zero In 1 litre at £7.99 and Lignum 1 litre at £10.97. Litre packs sat about £11–£18, and 5 litre tins about £24–£41. When use line and rate agree, best woodworm killer splits one piece from a run of boards. If they do not, wait.

Pets, drying, and roofs

Calling the fluid safe for pets is not a test. Keep people and animals off until the timber is dry, and follow the label. A cot or a room you cannot ventilate is the wrong place. The Society for the Protection of Ancient Buildings puts moisture below about 15% ahead of any chemical. A loft is a stop. Bats and their roosts are protected, and GOV.UK says not to use chemical timber treatments in or near a known roost if bats are present. A termite line does not make a UK tin more thorough. If every check has passed, follow how to use woodworm killer. If one has failed, buy nothing.

Common questions

Do I need a bottle if I only see old holes?
No. The Property Care Association says a dead attack does not justify treatment. Dark holes, sound timber, and no new dust after a week of watching mean you monitor the piece. Buy only when pale frass keeps returning under holes of about 1–2 mm on timber you can reach.
Can I buy a professional-only woodworm killer for a weekend job?
No. The Health and Safety Executive limits the public to biocides for the general public. A professional-only bottle is not a legal Saturday upgrade, even if the listing sells it. Match the user category and authorisation number to the current HSE list, and use the original container at the labelled rate.
Which tins name interior or exterior use?
Both Lignum tins state interior use. Zero In names internal furniture and living areas. Rentokil’s 250 ml listing says indoors and outdoors, which is still wrong for a raised bed in soil. Ronseal’s 1 litre recommended uses say exterior wood, against a title that says woodworm killer. Listings that ask about indoor use and never answer stay out of the basket.
Is “safe for pets” on a listing the same as a test?
No. These extracts are not a pet-safety trial. Keep pets and children away until the timber is dry, and follow the hazard lines. Barrettine’s published label warns of serious eye irritation and of the skin sensation linked to pyrethroids. If you cannot keep animals out for that drying time, do not buy the tin for that room.
What if the loft might have bats?
Stop. GOV.UK says not to use chemical timber treatments in or near a known roost if bats are present. A permethrin-only amateur tin, such as Lignum, Ronseal, or Zero In, is still the wrong buy while bats may be there. Rentokil lists more than one active, which adds a further restriction rather than a way round the rule.
Is a 5 litre tin better because the price per litre is lower?
Not on its own. Five litre tins in the 16 October 2026 extract sat about £24–£41, which looks kinder per litre than a bottle under £13. At about 300 ml per square metre, from Barrettine’s published label, 5 litres is a measured run of bare boards, not a saving on one chair. If no rate is printed, the large tin is a guess.

Related pages

Woodworm killer for furniture

Woodworm killer

Is woodworm active, or are those holes already old?

Best woodworm killer for a chair or a measured floor

How to use woodworm killer on bare, reachable timber

Sources

Public UK and manufacturer sources from the research digest, last checked on 16 October 2026.

  1. Health and Safety Executive — using biocides (retrieved 16.10.2026)
  2. Health and Safety Executive — product type 8 (retrieved 16.10.2026)
  3. GOV.UK — bat roosts and timber treatment (retrieved 16.10.2026)
  4. Property Care Association — woodworm (retrieved 16.10.2026)
  5. British Pest Control Association — insects that destroy wood (retrieved 16.10.2026)
  6. Society for the Protection of Ancient Buildings — wood-boring insects (retrieved 16.10.2026)
  7. Barrettine — 500 ml ready-to-use label (retrieved 16.10.2026)
  8. amazon.co.uk extracts, 16 October 2026 (retrieved 16.10.2026)