Article Loss Prevention

Japanese Knotweed – Professionals should know the law and their responsibilities

- by

Photo of Japanese knotweed invading a site recorded during a walkover survey.

Japanese knotweed is a non-native invasive bamboo-like plant that is very strong and grows incredibly quickly. It can cause damage to drains, paths, walls and foundations. Many mortgage lenders will not agree to lend against a property that is located within 7m of the plant.

In the County Court case of Waistell v Network Rail (2017), Network Rail was ordered to pay compensation to two home owners whose properties backed on to Network Rail land which was rife with Japanese knotweed. This case potentially opens the way for claims against owners of land containing Japanese knotweed and to property professionals advising them. The AGS have published Loss Prevention Alert No 67 which reminds Members of the law relating to Japanese knotweed, describes the Waistell case and the reasoning behind the Court’s decision, and discusses the responsibility Members have relating to Japanese knotweed when advising their clients on the purchase of land or on construction activities. AGS Members should also be aware of other invasive species such as giant hogweed which land owners could have a responsibility to control.

The case is significant as it holds landowners to account and imposes a positive duty on them to ensure that any knotweed that is on their property is not preventing neighbouring landowners from being able to sell their property for market value.

Damages can be claimed for costs of removing the Japanese knotweed or an order requiring the defendant to remove it, costs of any remedial works to the claimant’s property and diminution in value of the property.

The full Loss Prevention Alert 67 – Japanese Knotweed – Professionals should know the law and their responsibilities can be downloaded here.

Further information on Japanese knotweed and related issues can be found on the following websites.
Environment Agency (
Scottish Environment Protection Agency (
Royal Institution of Chartered Surveyors (
UK Government (
The Invasive Non-Native Specialists Association (

This article was contributed by David Hutchinson, Honorary Member of the AGS and featured in the March/April 2018 issue of the AGS Magazine, which can be viewed here.

Article Contaminated Land Laboratories Loss Prevention

Letter to the Editor

- by

Dear AGS,

Are AGS Members aware of the potential impact Japanese Knotweed (JKW) may have on the development of sites?

If this is not identified when carrying out walk over surveys and ground investigations, the additional cost to the client of clearing the plant from site and the possibility that the ‘Ground Investigation Specialist’ could be blamed for not identifying it in the first place as a potential ‘contaminant’, could result in significant potential liabilities, e.g. A site in the Midlands is currently clearing JKW off site at a cost of over £250,000, as an extra over cost!

The AGS and current British Standards for ground investigation (reporting guidelines) do not appear to specifically cover such potential ‘contaminants’. Should we not be providing advice to both Geotechnical/ Geo- Environmental specialists/ Clients etc in how to identify these invasive plants or at least provide them with guidance as to what specialists should be appointed to identify and deal with such problems? Is this part of our role? What do members think? The EA currently provide guidance notes on their web site

In addition the implications of a ground investigation contractor spreading the JKW by vehicle wheels/tracks, samples etc could again be costly. Whilst this weed is widely distributed in Cornwall and Wales, its encroachment into other parts of the UK is rapid.

Any comments or discussion back would be appreciated.
Chris Eaton, Geotechnical Developments (UK) Ltd

A Knotty Problem

Japanese Knotweed is an invasive perennial that can hinder the growth of many native species of plant. It can grow to around 3m high and expands rapidly once it takes hold of a site.

Japanese Knotweed was introduced to the UK during the 19th century as an ornamental plant and can be spread easily from the movement of contaminated soil. The plant is characterised by thick canes with red shoots and bears white flowers. It is notoriously robust and can survive being cut back due to an extensive underground root system.

The Wildlife & Countryside Act of 1981 makes it an offence to spread Japanese Knotweed and any excavated soil that is taken off site must be disposed of at a licensed landfill site.

The Environment Agency website: contains very useful information about knotweed, how to deal with it, and what precautions need to be taken if it is encountered on site