Two householders in Wales have been supported by the Court of Appeal in claiming for the reduced value of their properties due to an infestation of Japanese knotweed on neighbouring land, owned by Network Rail.

Stephen Williams and Robin Waistell issued claims in private nuisance against Network Rail on the basis that the Japanese knotweed on its land had: (1) encroached upon their properties; and (2) by being within seven metres of their properties, interfered with their quiet enjoyment of, and caused a loss of amenity in respect of, their properties by reducing their market value. According to the Council of Mortgage Lenders’ policy, where Japanese knotweed, a hardy bamboo-like perennial plant which grows quickly and strongly and spreads through its underground roots or rhizomes, is within seven metres of a habitable space, the valuation of a property can be affected and, indeed, a number of lending institutions make special provision in their lending policies for such a situation.

In the county court the recorder found that the claimants were entitled to succeed in a claim for private nuisance because of the reduced market value of their respective properties caused by the close proximity of Japanese knotweed. From 2008 or 2009 Network Rail should have known of the presence of the Japanese knotweed on its land, and by 2012 they should have known that it posed a reasonably foreseeable risk of causing damage or loss of amenity to the claimants’ properties. Actual knowledge arose from 2013 when the claimants first complained. In those circumstances, Network Rail’s treatment of the Japanese knotweed was inadequate and unreasonable and in breach of their duty as a landowner.

The Court of Appeal (Sir Terence Etherton, MR, Lady Justice Sharp and Lord Justice Leggatt) unanimously upheld the recorder’s decision, but for different reasons. The Master of the Rolls, with whom the other judges agreed, said the claimants could not claim in private nuisance merely because of the diminution in their properties’ market value, and it was wrong in principle for the recorder to hold that the presence of knotweed on Network Rail’s land within seven metres of the claimants’ properties was an actionable nuisance simply because it diminished the market value of the claimants’ respective properties because of lender caution in such situations. The purpose of the tort of nuisance was not to protect the value of property as an investment or a financial asset, but to protect the land’s intangible amenity value, which concerned landowners’ use and enjoyment of the land. That did not include the right to realise or otherwise deploy the value of the property in the owner’s financial interests, and to extend the tort of nuisance to include such a claim for pure economic loss would be a radical and unprincipled reformulation of its purpose and scope. 

However a claim did lie in respect of the encroachment of Japanese knotweed rhizomes because they had diminished the claimants’ ability to enjoy the amenity and utility of their respective properties. Japanese knotweed, and its roots and rhizomes, did not merely carry the risk of future physical damage to buildings, structures and installations on the land; its presence imposed an immediate burden on landowners, who faced an increased difficulty in their ability to develop, and in the cost of developing, their land, should they wish to do so, because of the difficulties and expense of eradicating Japanese knotweed from affected land. In this way, Japanese knotweed could fairly be described as a natural hazard which affected landowners’ ability fully to use and enjoy their property and, in doing so, interfered with the land’s amenity value.

The recorder’s awards of damages of £10,500 and £10,000 respectively were upheld.

Click here to access the judgments.