Japanese knotweed – what is it and what are the risks to homeowners?

What is Japanese knotweed?

Japanese knotweed is a rapidly spreading weed that is native to East Asia but arrived in Europe in the 19th century.  Sometimes mistaken for bamboo, Japanese knotweed can grow up to 3 metres deep and up to 7 metres across and above ground can reach heights of 2-3 metres.  Knotweed will die back to ground level over winter with bamboo-like stems emerging by early summer.

What is the impact?

The roots and branches of Japanese knotweed grow incredibly fast and so can cause significant issues for homeowners.  In some cases, the plant can be strong enough to break through decking, patios, foundations and even the flooring of a house in search for moisture and light.  In situations where Japanese knotweed is present it can seriously reduce the value of a property or make it unsellable.

Luckily, it is possible to treat Japanese knotweed, either with excavation or by treating the plants with herbicides.  Costs and time taken vary massively dependent on the scale of the problem.

Regulation and liabilities

Wildlife and Countryside Act 1981 – This covers the spread of non-native species.  If found guilty of allowing knotweed to grow and cause problems for others, individuals can be charged with a fine of £5,000 and 6 months in prison – or 2 years in prison and an unlimited fine.

 Environmental Protection Act 1990 – Along with the Wildlife and Countryside Act, this covers the disposal of knotweed.

Anti-Social Behaviour Orders (ASBO) – Police can take action, serving an ASBO against businesses and individuals who don’t control Japanese knotweed when could be reasonably be expected to do so.

The Law Society made changes to form TA6 s7.8 in February 2020, so it is now a requirement for sellers to declare with absolute certainty whether Japanese knotweed is or isn’t present.

To answer “no” to the presence of knotweed, the seller must be certain in saying it is not found within 3m of their property.  But because the root system cannot be seen and can travel great distances, it is virtually impossible to know it’s not there.

How can insurance help? 

Insurance policies are available to cover costs associated with any remediation notice including the cost to reimburse the enforcing authority in addition to the cost of altering, repairing or demolishing the property as a result of damage caused by Knotweed.  These types of insurance policies are designed to provide cover where the results on a TA6 Property Information form is either “No” or “Not known”.

Where knotweed is known to be present there are specialist firms who can carry out remediation works and provide an insurance backed guarantee.

To find out more, get in touch with Hayes Parsons’ Legal Indemnities expert, Alex O’Donnell.

Alex O’Donnell Cert CII
Account Executive
0117 930 1651 | 07471 038 915
[email protected]


This article was submitted to be published by Hayes Parsons as part of their advertising agreement with Today’s Conveyancer. The views expressed in this article are those of the submitter and not those of Today’s Conveyancer.

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