Expert Insights

Expert Insights

A weed ‘knot’ to be ignored – liability for Japanese knotweed

Homeowners need to be aware of an important recent decision about a particularly dangerous weed.  The Court of Appeal held that Network Rail was liable to pay damages in respect of Japanese Knotweed that was encroaching from the side of the railway onto neighbouring residential property.

Japanese Knotweed is a pernicious weed that spreads rapidly.  The roots can break through concrete and foundations causing a lot of damage.  Eradication requires a specialist, as it‘s very hard to remove manually or eradicate with chemicals.  In this case, Network Rail had actually carried out some treatment but the court found it to be inadequate.  Japanese knotweed has become increasingly well known in recent years, and is viewed as such a problematic weed that legislation covers its control and removal.  The mere presence of Japanese knotweed in or even near domestic gardens can make it difficult to get a mortgage which can seriously impact upon the marketability and value of affected property.

The facts

Mr Williams and Mr Waistell (the homeowners) owned two adjoining semi-detached bungalows in South Wales.  Network Rail owned the land immediately behind the two bungalows.  Japanese knotweed had been present on the embankment for at least 50 years.  It was reputedly imported because of its powerful root system to shore up steep railway embankments. The home owners succeeded in their claims both at the County Court and in the Court of Appeal, but for different reasons.  One of the interesting features of this case was that there was no evidence of any physical damage to the bungalows, nor of any change in the soil structure.

The decision

The County Court confirmed that the homeowners had a claim in private nuisance because they had suffered a loss of enjoyment through the diminution in value of their properties (as a result of lender caution in such situations).  Although the homeowners also succeeded in the Court of Appeal, the legal analysis was different. 

It confirmed that the homeowners could  not bring a claim merely because the market value of the properties had been affected.  It stated that Japanese knotweed is a classic example of an interference with the amenity value of the land.  The homeowners were entitled to damages because the very presence of the weed (or even just its roots) had affected their ability to enjoy their properties.  In addition to the risk of future physical damage to existing buildings, the presence of the weed would make it more difficult and probably more expensive to develop the land, should the owner wish to do so in the future.  This is because soil contaminated by Japanese knotweed is controlled waste under environmental legislation and requires specialist removal.

Points to note

Correct identification is important as the weed can easily be confused with other plants - there is also a particular variant of Japanese knotweed that is less troublesome.  You will need to call in the professionals if you need to remove Japanese knotweed from your land.  The PCA Invasive Weed Control Group provides a register of vetted consultants and contractors who are Japanese knotweed specialists.  This issue must also be addressed if you are buying or selling land and is covered by the standard pre-contract enquiries that the buyer’s solicitor should raise.

This is a welcome decision in that it confirms that landowners can recover damages in respect of land blighted by Japanese knotweed.  However, it also serves a warning that you must not ignore the presence of this weed on your land, or you may face liability to neighbouring landowners.

This article was written by William Marriott. If you would like to speak to him about any aspect of buying, selling or owning a house, email him at or call him on +44 (0) 1483 252 519




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