• February 4, 2021

Ignoring the risk of Japanese Knotweed could prove costly

Japanese Knotweed (Fallopia japonica) is an invasive non-native species of weed, identifiable by its red bamboo-like stems and green spade-shaped leaves. But it could cause personal, legal and financial problems.

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Japanese Knotweed spreads quickly and is known to cause damage to the structures and substructures of buildings by taking advantage of weak points in the buildings' fabric, such as cracks in masonry, caused by movement in the substructure. Consequently, the presence of Japanese Knotweed is an important consideration during a property transaction or property development.

Failure to manage Japanese Knotweed may lead to legal disputes, substantial fines, or even imprisonment


Under the Wildlife and Countryside Act 1981, Japanese Knotweed is classified as a controlled plant. This means that it is illegal to allow this species to grow in the wild. Anyone failing to take steps to prevent its spread can be fined as much as £5,000 or face up to two years in prison.  Further legislative regulations apply to Japanese Knotweed control, such as the Anti-Social Behaviour Crime and Policing Act 2014, the Environmental Protection Act 1990 and the Infrastructure Act 2015. All can give rise to legal action for the negligent cultivation of Japanese Knotweed if the plant is allowed to spread from a property owner's land onto neighbouring properties or into wild habitats and public spaces.

Failure to undertake reasonable measures to control the weed can result in legal action, with two cases worthy of note:

Williams & Waistell v Rail Infrastructure Ltd, 2018

Williams & Waistell successfully sued ‘in nuisance’ Rail Infrastructure Ltd for not removing knotweed from land that bordered dwellings they owned. Damages were assessed at £10,000 with £5,000 going towards remedial costs.

Ryb v Conway Chartered Surveyors and Others, 2019

A house buyer successfully sued a surveyor for failing to spot Japanese Knotweed in a residential garden. The claimant successfully argued that the surveyor should have taken photographs and made a record of the knotweed. Furthermore, the claimant argued that they would not have purchased the property or would have demanded a price reduction if they had known of the knotweed. Damages were assessed at £50,000.

Although these two cases are distinctly different, it will be interesting to see what emerges from future case law.

Why answering ‘not known’ to the presence of Japanese Knotweed should be accompanied by the relevant insurance

 
In February 2020, the Law Society amended its guidance accompanying the home seller's property information form (TA6), regarding Japanese Knotweed.

The Law Society's latest guidance advises that sellers who respond 'no' to the presence of Japanese Knotweed on their land must be absolutely certain that no rhizomes exist in the grounds of their property or within three metres of its boundary. 

Given that this rapacious plant can grow rapidly from a tiny, undetected rhizome fragment, definitively stating that it does not exist on one's property may leave the seller open to a misrepresentation claim. Consequently, the general advice to sellers will likely be to give a 'not known' answer to the Japanese Knotweed question and place the responsibility on the purchaser to establish whether the property is free of infestation or not.

You can find out more here

While a 'not known' response may trigger alarm bells, the home buyers’ or home sellers’ solicitor can take out a Japanese Knotweed indemnity policy to cover treatment costs, any reduction in property value following treatment, and other agreed costs and expenses. 

The DIY removal of Japanese Knotweed is not a reliable solution


The control and/or disposal of Japanese knotweed can be risky and difficult and should be undertaken by professionals. Only approved herbicides can be used to tackle an infestation, and it usually takes three years before the underground rhizomes become dormant. If the plant is to be disposed of by burying, then it must be buried five metres deep and at the same site that it came from. If it is to be burnt, then the Environmental Agency and local council environmental health office must be notified in advance. There is a raft of other requirements and recommendations that can be found here

It is prudent, therefore, that the party concerned engage the services of a professional who operates within the guidelines of the government's regulatory position statement 'treatment and disposal of invasive non-native plants: RPS 178' and has the relevant environmental permit. 

You can check for the prevalence of Japanese Knotweed across the UK by postcode here.

Other types of knotweed


In addition to Japanese Knotweed, Giant Knotweed (Fallopia sachalinensis) and Bohemian Knotweed (Fallopia x bohemica), which is a hybrid between Giant Knotweed and Japanese Knotweed, are highly invasive pest plants. Some insurers will consider including these plants within the policy coverage. 

One thing is certain: Japanese Knotweed is here to stay.

Contact us


Contact the Legal Indemnity team at Clear by emailing legal-indemnities@thecleargroup.com or click below to find out more.

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