In a recent case of Davis v Bridgend County Borough Council [2023] EWCA Civ 80, the Court of Appeal held that the diminution in value of a property following encroachment of Japanese knotweed from neighbouring land was a recoverable loss.

Japanese knotweed (Knotweed) is an invasive non-native plant which can cause damage to buildings and biodiversity, can be difficult and costly to remove and affects the value and insurability of property. 

In this case, Mr Davis bought a property in 2004 which adjoined land owned by Bridgend County Borough Council (Council). In 2012, the RICS published a report describing the difficulties that Knotweed could cause. The Council did not take any steps to treat the Knotweed on its land until 2018. Mr Davis noticed the presence of Knotweed on his property in 2019 and raised concerns with the Council, which ultimately resulted in a court battle. In the first instance decision, the District Judge found that the Council was in breach of its duty in nuisance between 2013 and 2018 and this was accepted. The question was whether this duty continued after 2018 once the Knotweed had been treated on the Council's land. Mr Davis sought to recover £4,900 for the residual diminution in the value of his property after 2018.

This claim was refused at first instance with the District Judge relying on the Court of Appeal decision in Williams v Network Rail [2018] EWCA Civ 1514 (Williams) where it was held that it was incorrect to find that diminution in the value of a property simply due to the presence of Knotweed was an actionable nuisance as it is pure economic loss, i.e. there was no physical damage or interference. The District Judge also stated that the purpose of the tort of nuisance is not to protect the value of property as an investment or financial asset.

The Court of Appeal pointed out in its appeal decision that the key word was “simply”, and that it was important to look at the elements necessary to complete the tort of nuisance. In a case where the elements of nuisance are satisfied, it does not mean that a claimant cannot recover for damage to their economic interests. Williams holds that if Knotweed on the defendant’s land, even if close to the boundary, causes a reduction in market value of the claimant’s land but such reduction does not result from physical damage or interference, it does not amount to nuisance. Williams does recognise that if the value of property is diminished as a result of interference with quiet enjoyment or amenity due to physical encroachment of Knotweed, damages including diminution of the value can be available.

The Court of Appeal briefly considered a submission by the Council in which they stated that no risk to the structure of Mr Davis' property was identified and that there was no prospect of developing the property. The Court rejected this submission on the basis that once a natural hazard is present, the quiet enjoyment or land’s value is diminished which, in tort, amounts to nuisance as a result of physical interference.

This case cost the Council £300,000 in legal costs. Although the damages recovered by Mr Davis was £4,900, this is more a case of principle. Prior to this decision, a property owner could not make a claim against a neighbouring owner if the value of their property was diminished due to the presence of Knotweed on their land post-treatment. This case therefore serves as a timely reminder for land owners to instruct a specialist to treat Knotweed as soon as it is identified as the consequences can be costly. It also potentially opens the door for future claims where Knotweed treatment was commenced after the plant had already spread to neighbouring land.

Please note that this information is provided for general knowledge only and therefore specific advice should be sought for individual cases. 

For further information, please contact Marie Bennett-Staples