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Best woodworm killer for a chair or a measured floor

Updated: October 2026

You have one chair with fresh dust, or bare boards you can pace out, and amazon.co.uk is sorting the results by stars. The best woodworm killer in this extract is the tin whose size and use wording match that job, compared with a 5 litre can bought because the price per litre looks lower. It is not a winner for a loft, a roof, or a raised bed. This page, from the Products Compared editorial team, sits with the [woodworm killer comparison](/hub/raised-beds-greenhouses-and-compost/woodworm-killer), which sets these listings 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 at no extra cost to you.

You have one chair with fresh dust, or bare boards you can pace out, and amazon.co.uk is sorting the results by stars.

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.A small piece, not a whole floor
  2. 2.A bare area you can measure
  3. 3.Listings to leave for a roof or a planter
  4. 4.What best cannot mean here

A small piece, not a whole floor

A chair or a greenhouse rail you can lift is a 250 ml to 1 litre job if the dust is fresh and the timber is bare. Rentokil’s 250 ml tin is £9.59, with indoors and outdoors on the bullet and 629 reviews, though nozzle complaints mean you should test the spray head first. Joints and varnish are on woodworm killer for furniture.

A bare area you can measure

A 5 litre tin matches a bare area you can measure, and only if the label’s rate and use line agree. Lignum’s 5 litre tin is £24.39 and interior, the lower price in this band for a floor you can strip, and the wrong tin for timber left in the weather. As a rule of thumb, 250 ml per square metre makes 5 litres about 20 square metres of bare face, a run of boards rather than one chair. If the bullet omits the rate, read the tin before you size up. Coats and drying, once the label states a rate, are on how to use woodworm killer.
Rentokil Rentokil PWT25 woodworm treatment fluid 250 ml

Testsieger

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

Listings to leave for a roof or a planter

Lignum’s interior bullets rule it out for a raised bed or a planter that stays wet, compared with a chair you can bring indoors. A loft is a separate stop: on the reading of Natural England’s timber list used here, Lignum, Ronseal, and Zero In appear as amateur permethrin-only examples, while Rentokil’s fluid is multi-active. The number on the tin still governs, and you should not spray a loft until bats are ruled out. A roof you cannot see all round is not a DIY coat, because fluid does not replace crumbled timber. An outdoors line on Rentokil’s 250 ml tin is not a licence to soak a planter. If you are unsure the dust is new, start with is woodworm active or old.

What best cannot mean here

This extract cannot crown one house brand as the best woodworm killer. Ronseal’s 4.8 from seven silent reviews, Zero In’s five reviews, and Soluguard’s 6,621 reviews, including failures on mahogany and floors, are not a UK laboratory test. Soluguard’s bullets say 0.2% permethrin, while Safeguard’s own page states 0.25% and a different rate, so that page is a conflict, not a replacement spec. The woodworm killer buying guide checks activity, user category, and use line before stars. If the label and the job disagree, buy nothing.

Common questions

Which tin fits one chair?
For one chair you can turn and keep indoors, Rentokil’s 250 ml tin at £9.59 or Zero In’s 1 litre tin at £7.99 is the closer size. Rentokil has 629 reviews, though nozzle complaints mean you should test the spray first. Zero In is water-based permethrin for living areas, with only five reviews. Lignum at £10.97 is interior only, so leave it if the chair goes back into a damp greenhouse. Varnish will stop the fluid reaching the larvae.
Which tin fits a measured bare floor?
Use a 5 litre tin when you can measure bare boards and the label states a rate. Lignum at £24.39 is interior, Cuprinol at £28.95 is water-based with the use line n/a, and Ronseal at £40.76 names eggs from four thin reviews. Other shops print about 200 to 300 ml per square metre, a scale check rather than these bullets. About 20 square metres of bare face, as a rule of thumb, justifies 5 litres only if the tin agrees.
Why is the cheapest 1 litre not automatically the one to buy?
Zero In at £7.99 is the lowest 1 litre price here, and its water-based permethrin wording can fit a small indoor piece. Five reviews are weaker evidence than Rentokil’s 250 ml tin at £9.59 with 629 reviews, though that smaller tin has nozzle complaints. Zero In is the wrong saving if the use line excludes your room, or if the floor needs 5 litres. A low price and a matching label are different tests.
Why is a high star rating from seven reviews weak evidence?
Ronseal’s 1 litre tin shows 4.8 from seven reviews and no written text. That sample can miss a nozzle fault, a dented can, or a floor that did not dry. Soluguard’s 4.4 from 6,621 reviews is thicker, and it still includes mahogany and floor complaints. A higher star on seven silent reviews is not the stronger proof, and stars never show whether the woodworm was active.
Which listings should I skip for a loft or a raised bed?
Skip Lignum for a raised bed or an outdoor planter, because the bullet is interior only. Skip a loft spray until bats are ruled out, even where Lignum, Ronseal, or Zero In appear as amateur permethrin-only examples on Natural England’s timber list. Rentokil’s fluid is multi-active on that reading, and the number on the tin still governs. Skip Deadline, which is professional use only, and skip a roof you cannot see all round.
Is Soluguard’s 0.2% on Amazon the same as the maker’s 0.25% page?
Treat the two figures as a conflict. The amazon.co.uk listing states 0.2% permethrin at £15.98. Safeguard’s own page states 0.25% and a coverage rate that does not match the bullets. Notice the clash, then follow the label on the tin you can buy. Do not average the two strengths, and do not assume the web page has updated the Amazon listing.

Related pages

Woodworm killer

Is woodworm active, or are those holes already old?

Woodworm killer buying guide: checks before you buy

Woodworm killer for furniture you can turn and isolate

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)