Japanese Knotweed UK Case Law

Japanese Knotweed UK Case Law

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Japanese knotweed treatment on commercial site

The number of Japanese knotweed related cases going to court is increasing, with significant financial penalties for those that cause nuisance or have been negligent with respect to Japanese knotweed. We take a closer look at the headline cases and laws relating to this.

In 1981, Japanese knotweed was one of the first plants to be added to the Wildlife and Countryside Act, making it illegal to commercially sell or allow the plant to spread to the wild. Further acts of legislation from 1990 (The Environmental Protection Act 1990, Duty of Care Regulations 1991, and RPS 178) governed the handling and disposal of the plant and materials contaminated by the plant material.

Additionally, in recent years we have seen a sharp rise in private litigation cases surrounding Japanese knotweed. 2018 saw the first successful documented case law for private nuisance in respect to Japanese knotweed. Now claims for Private Nuisance, Professional Negligence and Misrepresentation are more commonplace, as well as the ability to fall foul of an ASBO and be served a Community Protection Notice with a fine for failing to act and control and spread of knotweed.

Private Nuisance

Williams & Waistell v Network Rail Infrastructure Ltd [2018] EWCA Civ 1514

Presence of knotweed on neighbouring Network Rail land caused an actionable claim of Private Nuisance by Williams & Waistell.

The Recorder at first instance found that both properties had been the subject of actual encroachment by knotweed, but neither had suffered any physical damage and therefore there was no actional nuisance. However, it was held that both properties had suffered a devaluation in their market value, because of the continuing presence of knotweed on Network Rails land which was interfering with their quiet enjoyment of their properties.

On appeal, the Court of Appeal held that the initial Judgment had been wrong in principle to find that the mere presence of knotweed within 7 metres of the Claimants’ land was an actionable nuisance because it diminished the market value of their properties. However, the Court of Appeal did find that once encroachment has been established, then this would automatically amount to physical damage and an actionable nuisance. They, therefore, upheld the original damages award.

Invasive Species Survey
Encroachment of Knotweed from Railway Land


Mr Williams was awarded:

  1. £4,320 for a treatment programme and an Insurance Backed Guarantee
  2. £10,500 for a residual diminution in value of his property after treatment
  1. Miscellaneous loss of £200
  2. General damages of £1,400

Mr Waistell was awarded:

  1. £4,320 for a treatment programme and an Insurance Backed Guarantee
  2. £300 for the cost of a Japanese knotweed survey
  1. £10,000 for a residual diminution in value of his property after treatment

Smith & Another v Line [2017]

The defendant sold a house to the claimants in 2002 for £200,000 retaining the majority of the land for her own use.

The claimants discovered knotweed on their land in 2003 and complained to Ms Line who tried to argue that it had actually encroached from the claimants’ land onto hers. By 2013, the claimants had successfully treated the knotweed on their land and requested that Ms Line treated hers because it was coming ever closer to their property. She refused and maintained that the knotweed had encroached onto her property.

The claimants issued a nuisance claim seeking an injunction or, alternatively, damages.

Joint experts were instructed who concluded that the knotweed had originated on Ms Lines land and that the continued presence of Japanese knotweed, untreated, on Ms Line’s land close to the boundary with the claimants’ land had effectively reduced its value by 10%.

Invasive Species Survey
Encroachment of Knotweed from Neighbouring Land

The claimants argued nuisance based on:

His Honour Judge Carr found that the claimant’s land had not been damaged but that the knotweed on Ms Line’s land interfered with the claimants’ enjoyment of their land.


The claimants were granted a mandatory injunction requiring Ms Line to enter into a contract with a reputable contractor to treat the Japanese knotweed on her land and she was ordered to pay the Claimants’ costs.

Professional Negligence

Ryb v Conways Chartered Surveyors [2019]

Conways Chartered Surveyors failed to identify Japanese knotweed during a Level 3 Building Survey giving rise to a claim of Professional Negligence against them. Expert evidence at the trial identified that the knotweed should have been clearly visible during the survey.


Being found negligent, Conways were ordered to pay £50,000 in damages, which included treatment and residual diminution in value of the property.

Davis v Connells Surveying and Valuation Ltd [2018]

Davis took Connells Surveying to court for Professional Negligence for failing to identify knotweed on hers and the neighbouring property during an inspection for the purpose of preparing a residential mortgage valuation for the lender.


The court found no evidence to support the presence of knotweed on site, and that identification of knotweed in the neighbouring property was outside the scope of the valuation survey and did not uphold the claim.

New-Build House on Knotweed Contaminated Land (Sherwood Homes) [2019]

By agreement, the defendant agreed to construct and sell the property and the client agreed to purchase it. The agreement incorporated the Standard Conditions of Sale. The following were implied terms of the agreement by virtue of s13 of the Supply and Goods and Services Act 1982 and/or at common law:

  • That the defendant has undertaken/would undertake landscaping and development of the garden with all reasonable care and skill to be expected of a reasonably competent developer.
  • That the defendant has complied/would comply with industry guidance relating to development and/or contaminated land including but not limited to the Environment Agency Code of Practice.
  • That the dwelling house and garden comprising the property would be reasonably fit for the purpose, namely fit for human habitation.
Invasive Species Survey
New-Build Japanese Knotweed Infestation

Expert evidence confirmed that Japanese knotweed was present on the site at the time of the purchase via photographs provided in the initial knotweed report. Furthermore, there were online Google Earth Street view images providing evidence of a historic infestation of mature Japanese knotweed across a large area of the site as it stood as wasteland prior to purchase and development.

The knotweed expert explained that the crown material and above ground stems from current and previous seasons would likely have been visible prior to the building of the client’s property. They believed significant rhizome material would have been encountered by the contractors carrying out the earthworks and other general construction works. Mature knotweed rhizomes were extensive and deep, spreading several metres in the ground beyond the area occupied by the aboveground stems, and usually up to 2 metres deep, sometimes deeper.

In addition, witness statements were obtained from the client’s neighbours detailing the condition of the site prior to construction and the witnessing of the ground upon which the property now stands, being scraped by a workman who they understand was acting for the defendant.

The knotweed expert noted that it was likely that the defendant had undertaken a shallow soil “scrape” of the infested area, but such treatment would have been inadequate to remove the plant and prevent recurrence of growth.

The presence of Japanese knotweed at the property was not disclosed at the time of sale. The client brought a claim against the developer on the following bases:

The client claimed the sum of £52,000 for damages.


The defendant did not attend the trial and judgment was awarded in favour of our client in the sum of £52,000 plus £8,433.97 in interest.


Bristol City Council v MB Estate Ltd [2018]

In 2018, Bristol City Council prosecuted MB Estate Ltd for failing to control the spread of Japanese knotweed. The council had served the property owner with a community protection notice in May 2017, but after no attempt was made to comply with the notice, the council prosecuted the property owner using the Anti-Social Behaviour, Crime and Policing Act 2014.

Failing to Control Knotweed Risks a Fine
Failing to Control Knotweed Risks a Fine


MB Estate Ltd was fined £18,000 plus costs and ordered to instruct a professional knotweed company to deal with the infestation.


When selling a house, the vendor completes a Law Society form called the “Property Information Form”, or a TA6 which is a legally binding document. There is a question within the form that asks whether the property is affected by Japanese knotweed.

If the vendor lies and ticks “No” when they know that the property is affected and this can be subsequently proven by the buyer, the vendor can be sued for Misrepresentation.

To date, there are no known Misrepresentation cases that have been taken to court. However, it's quite possible that Misrepresentation cases have been settled out of court.

Japanese Knotweed is NOT to be Ignored

If your property is affected by Japanese knotweed, it is in your interest and within your Duty of Care to control the knotweed on your property. The sooner knotweed is identified and treated, the easier it is to manage.

If you suspect you have knotweed on your property, you can use our free Knotweed Identification service; just take a couple of photos of the suspect plant and send them to us. We’ll let you know if it’s knotweed and we can then offer advice and help you take the next steps to deal with the infestation.

Don’t fall foul of UK law or put yourself in a position where someone can take private action against you. We’re the UK’s trusted Japanese knotweed experts. Contact us because we can help.

Trust in Japanese Knotweed Ltd, the UK’s Experts

If you’re a property owner and think you may have knotweed on your property, or you’ve bought a property that could be affected, we’re here to help.

We are the UK’s largest dedicated Japanese knotweed and other invasive species treatment and removal company with PCA accreditation. We offer a range of services to both residential and commercial clients including:

Get in touch. Call us on 0333 2414 413 or email us at contact@knotweed.co.uk

*Surveys on mainland England, Wales and Scotland are free. However, if we find the property not to be affected by Japanese knotweed there is a charge of £165 +VAT and an accompanying Visual Assessment Report.

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