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Japanese Knotweed - don't shrug it off! Have you checked your house?

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Japanese Knotweed is an intrusive plant that spreads swiftly. The roots can reach depths of up to three meters and it can seriously damage infrastructure and buildings. Concrete cannot withstand its strength, which is why it is causing problems for sellers and buyers across the country.

In addition, Japanese Knotweed can decrease the value of the property by 5%–10%. In severe circumstances, it can render the property un-mortgageable.

It is important to note that although it is legal to have Japanese Knotweed on your property or land, failing to notify others of its presence and allowing it to spread beyond the boundaries of your property or land can have legal repercussions.

The only way to eliminate it is through excavation or years-long treatment plans, and even these could not be long-term fixes.

Selling the property

As a requirement for the sale procedure, sellers are obligated to reply to a question on the TA6 form regarding whether or not knotweed has impacted the property they are selling. Homeowners can now only respond "no" to the question, ‘’Is the property affected by Japanese knotweed?’’ if they are assured that no knotweed is present in the property boundary or within three meters of it.

A vendor should always mark "not known" on the form if they are uncertain as to whether knotweed currently exists or has ever existed.

The seller is required to disclose on the TA6 form whether knotweed has affected or been present on the property. A recent decision in Downing v Henderson [2023] confirms that the court will not consider it favourably if a seller responds to this question dishonestly. Here, the claimant, Mr. Downing, after acquiring the home, discovered the invasive plant in the garden. The defendant was forced to pay £32,000 in damages, which covered the cost of the reduction in the value, the costs of investigating and excavating the weed, and £95,000 in relation of costs for his misrepresentation.

Although builders and developers are not under an obligation to complete the TA6 form when acting as sellers, it is vital that the buyer ensures that specific enquiries are raised by their solicitor validating their historic and current position relating to the Japanese Knotweed.

Survey when buying the property

A prospective homeowner should always carry out the survey, making sure to include the garden and, if feasible, the gardens of neighbouring properties. The same applies for the apartments. Knotweed infestation may have an impact on the building's structural integrity and raise significant service charge obligations.

Surveyors have a duty of care to buyers to identify Japanese knotweed and risk being sued for negligence if they fail to do so. The legal precedence has been reaffirmed in recent case law. In Ryb v Conways Chartered Surveyors [2019], the claimant, due to his poor vision, relied considerably on the full building survey. He ordered it to be conducted when purchasing the property. It was found that, at the time when the survey was conducted, the property was affected by knotweed. Taking into consideration the evidence, Mr Ryb was awarded £50,000 in damages after spending £10,000 to remove it after discovery.

If you are looking to sell or buy property, our Property Team at Johnson Astills can assist you.

If you are experiencing issues with encroaching knotweed from neighbouring property and you would like to discuss your situation, contact our Dispute Resolution Team.

Please get in touch with Johnson Astills today and we would be more than happy to discuss your requirements further. Please call us at our office in Leicester on 0116 255 4855 or our office in Loughborough on 01509 610 312 and ask to speak to a member of the Property Team. Alternatively, you may prefer to email us at or fill in our enquiry form.