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09 March 2023

A knotty issue – can landowners recover damages due to Japanese Knotweed on a neighbour’s property?

3 mins

A recent Court of Appeal case has confirmed that a landowner is able to claim damages for the diminution in value to their property caused by Japanese Knotweed on neighbouring land.

Japanese Knotweed is a destructive and invasive plant that spreads quickly and can cause physical damages to buildings if not treated or contained. It spreads via its large underground network of roots, or rhizomes.


In 2004, the Claimant, Mr Davies, purchased a property that backed on to railway sidings. In 2017, he discovered the presence of Japanese Knotweed on his property, which had spread from a neighbouring property, owned by Bridgend County Borough Council.

It was agreed that the council had been aware of the presence of the Japanese Knotweed since around 2013, but did not take steps to treat it until around 2018.

Initial proceedings

Mr Davies initially issued proceedings for nuisance, and part of his claims were rejected as the Japanese Knotweed had not actually caused any physical damage to his property and he could not claim for ‘pure economic loss’.

However, Mr Davies argued that the stigma of there being Japanese Knotweed on a neighboring property (even if it had been treated) reduced the value of his property, for which he should be awarded damages.

Encroachment of the Japanese Knotweed

The Court of Appeal stated that in cases where Japanese Knotweed was present on a neighbouring property, there was no nuisance if there was no evidence that the Japanese Knotweed had encroached upon next door or where the encroachment had been trivial.

However, in Mr Davies’ case, there was evidence that the rhizomes had encroached onto Mr Davies’ land and such encroachment was not trivial. In such circumstances, this amounted to a physical interference with Mr Davies’ property and therefore, consequential losses including diminution in value were recoverable.

The outcome

The council argued, amongst other things, that as the rhizomes had been present before 2004 when Mr Davies purchased his property, they should not be responsible for any loss that is suffered before their breach (of failing to treat the knotweed between 2013 and 2018), as such loss cannot have been caused by their breach. The court rejected this argument and said that the nuisance was a continuing nuisance and that the harm to Mr Davies’ quiet enjoyment of his land persisted.

Mr Davies was awarded the relatively low sum of £4,900 for the diminution in value to his property. However, it was estimated that legal costs ran into hundreds of thousands of pounds, that the council will also now be responsible for paying.

The implications of Mr Davies’ case

The case is expected to pave the way for many similar claims by landowners whose properties are next to land where Japanese Knotweed is growing. However, each case will turn on its own specific facts, and claimants will need to prove that the knotweed has actually encroached upon their land, and that such encroachment is not trivial, before they will be able to succeed in their claims for diminution in value to their property.

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