In a decision that has significant implications for landowners, the Court of Appeal has held that landowners may be liable to pay damages if Japanese knotweed (the plant, or its roots or rhizomes) enters neighbouring land from their property.

In Network Rail v Williams and Waistell, the Court of Appeal made clear that:

  • Knotweed encroachment constituted “an unreasonable interference” with the enjoyment of the claimants’ properties. The pervasiveness of knotweed roots and its rhizomes prevents development and interferes with a property’s amenity value.
  • A final mandatory injunction should be available to a claimant even though there has not been any physical damage to the property caused by knotweed. Sir Terence Etherton, Master of the Rolls, said that Japanese knotweed “affects the owner’s ability fully to use and enjoy the land. They are a classic example of an interference with the amenity value of the land.”

What was the dispute about?

The appeal concerned a 2017 County Court claim brought by two residential property owners who were awarded almost £31,000 in damages from Network Rail, arguing that the Japanese knotweed on the neighbouring Network Rail land encroached on their properties, constituting a “private nuisance” that affected their ability to enjoy the land.

The County Court found that by not addressing a known knotweed problem, Network Rail had breached its duty and the fact that knotweed was present on the adjoining land had caused a continuing nuisance and damage to the properties.

What did the Court of Appeal decided?

The Court of Appeal upheld the County Court’s decision, but for different reasons.

The Court of Appeal found that damages were not recoverable on the basis of the simple presence of knotweed on neighbouring land having an impact on market value of a property. This would have extended the tort of nuisance to include “pure economic loss”.

However, the Court of Appeal reached the same result by finding that the encroachment of knotweed onto neighbouring land had caused a loss of amenity and risk of future physical damage. This was an actionable basis for a nuisance claim, for which in an appropriate case a claimant could obtain an injunction and/or damages.

Network Rail was refused leave to appeal this decision further to the Supreme Court, although it may still petition directly to the Supreme Court.

What does this mean for landowners?

The ruling is particularly significant for large property owners with land that might be susceptible to knotweed problems. It makes clear that the responsibility for knotweed encroaching onto another property lies with the owner of the property that it spreads from. We expect that this new legal clarity over knotweed encroachment will encourage many more private nuisance claims.

Landowners such as public bodies and housing developers must consider taking reasonable steps to prevent or minimise encroachment of Japanese knotweed onto adjoining land.