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Japanese knotweed cost guide

Guideline prices for treatment, excavation and root barriers, based on figures published by the Property Care Association.
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Type of work

Where these figures come from

The figures are the indicative cost guideline published by the Property Care Association (PCA) for valuers and surveyors in December 2022. They are the most authoritative published UK figures available, and we present them without adjustment.

What affects the price

  • The size and maturity of the infestation, and how far the rhizome has spread underground.
  • The method: herbicide is usually far cheaper than digging it out.
  • Access for people and machinery.
  • Waste: how much soil has to be removed, and disposal and landfill charges.
  • Whether you need a management plan with an insurance-backed guarantee for a lender.

Frequently asked questions

How much does Japanese knotweed treatment cost?

The Property Care Association's guideline for a residential herbicide treatment and control programme on 1 to 25 m² is £2,000 to £4,000. Larger or more complex sites cost more.

Why is excavation so much more expensive than herbicide?

Digging usually extends 2 to 3 m beyond the visible plant and 1 to 2 m deep, so even a small stand can produce a large volume of contaminated soil. Excavation, transport and landfill charges add up quickly. The PCA's guideline is £3,000 to £6,000 for 1 m² and £8,000 to £16,000 for 10 m².

How long does knotweed treatment take?

Herbicide control usually takes at least four years, typically two years of treatment followed by two years of monitoring, and plans often run longer. RICS notes that chemical control needs at least four years of treatment and monitoring before a completion certificate.

Are there cheaper options?

Some councils offer their own treatment services. For example, Neath Port Talbot Council lists a five-year domestic spray plan at £1,448.07 including VAT, but it doesn't include an insurance-backed guarantee, which mortgage lenders often want.

Sources

  1. Japanese Knotweed: Guidance for Professional Valuers and Surveyors (December 2022), Property Care Association
  2. Japanese knotweed and residential property (PDF, October 2022 reissue), RICS
  3. Japanese knotweed and the built environment (HC 1702, May 2019), chapter 3, House of Commons Science and Technology Committee
  4. Japanese knotweed treatment service, Neath Port Talbot Council

Other tools

Photo check

Upload a photograph for an indicative assessment of whether the plant could be Japanese knotweed.

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RICS category checker

Find out which of the four RICS management categories a surveyor is likely to assign to the property.

Check the category

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We can introduce you to up to three Property Care Association members who cover your area.

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