Legal Victory In UK Japanese Knotweed Case Could Lead To More Claims

A significant legal victory in a case brought by a householder affected by Japanese knotweed has raised the prospect of an increase in claims from people stricken by the hazardous plant.

The court of appeal ruled that a homeowner could recover damages for a loss of value of their property from having had Japanese knotweed, even if it had been treated. Marc Davies was awarded £4,900 from Bridgend council in south Wales in a judgment that his lawyer, Tom Carter, said established that one could recover damages for the stigma attached to the house, even after knotweed had been eradicated, and not just physical damage caused by it.

“Inevitably, if you’ve had knotweed and then had it treated, the rhizomes (roots) are still there in the ground, even though it’s been treated,” he said. “There’s then a stigma that’s attached [to the house].

“The importance of Davies is that it has confirmed beyond doubt that that loss [on the house value] can be recovered and that’s really the crucial issue.

“If the court of appeal had said no on that point, then anyone affected by knotweed could get the treatment costs but then they’d be left out of pocket for this loss of value of their home. And if they were to sell their home a year, five years later or whenever, they’d still suffer a loss at that point they wouldn’t have been able to recover.”

Japanese knotweed can take five years to treat. It can grow to 3-4 metres in just 10 weeks and its rhizomes can spread 7 metres horizontally underground and compromise the structure of buildings.

The species was introduced by botanists into Britain in the 19th century as an ornamental plant, with Victorian engineers purportedly using it to stabilise railway embankments. Network Rail – along with local authorities – finds itself as the defendant in a large number of cases.

The principle that adjoining owners could be sued for encroachment of Japanese knotweed was established by the court of appeal in a 2018 case, which Carter also acted in, brought by the owners of two adjoining bungalows in Maesteg, south Wales, against Network Rail.

Last month, a house seller was ordered to pay £32,000 in damages plus legal costs for misrepresenting to the buyer whether there was Japanese knotweed at the property. Surveyors have also been sued for professional negligence for failing to identify its presence.

Chun Wong, partner at Hodge, Jones & Allen solicitors, said the Davies case would probably encourage claimants at a time when the number of cases was already growing.

She said: “It’s talking about what happens after the knotweed has been treated so it’s been found in the garden, hasn’t caused physical damage per se, but just having its presence because of the stigma attached … means somebody is going to pay less for this house than if the house had no knotweed at all.

“Whether this will open floodgates, I think time will tell. I suppose it just makes it easier for homeowners who have the presence of knotweed without actual physical damage to think: ‘Maybe I should make a claim.’

“The public are more aware and more educated about knotweed, the dangers of knotweed … and so, therefore, people are more prepared to litigate over it.”

Carter estimates he has already acted in 200 cases relating to Japanese knotweed and has another 100 outstanding.

He said: “The knotweed landscape probably will stay [busy] for the foreseeable future … and I can see defendants probably fighting more in that they no longer have an argument about claimants being unable to recover for diminution [of property price], so the value of the claims are higher.

“Whether it leads to an increase in claims I don’t know because I’ve got hundreds already and it’s been going on for years now – but I can’t see the issue going away.”