Don’t get in a Knot!

Property / 21 May 2018

You may have seen the case of Smith v. Line reported in the press recently.  This is the second of two cases concerning Japanese Knotweed and the damage it can cause to property which the courts have had to consider of late.

What is Japanese Knotweed?

According to the RICS, Japanese Knotweed (Knotweed) is “regarded by the International Union for the Conservation of Nature as one of the world’s top 100 invasive species.  It [produces] underground stems and or roots characterised by its destructive nature and rapid spread

Because of these characteristics, Knotweed can cause significant damage to property – the underground stems and roots penetrating drains, pipework, patios, foundations, walls and even concrete hardstanding and driveways.  This damage could therefore affect a property’s value, as well as its marketability and insurability.  As such, Knotweed is heavily regulated, with its spread being controlled under the Wildlife and Countryside Act and waste containing Knotweed being controlled under the Environmental Protection Act (the EPA).  Also, and in much the same way as works affecting materials containing asbestos, treatment of Knotweed must be undertaken by a competent and accredited contractor.

Offences and potential liability

Failure to dispose properly of waste which contains Knotweed is a criminal offence under the EPA and, whilst land affected by Knotweed is unlikely to be classified as contaminated land for the purposes of the EPA, a Local Authority can take action against a landowner where that owner allows the amenity of the land (or adjoining area) to be adversely affected.

It is this loss of amenity which can also give rise to an action in common law for nuisance, enabling an adjoining landowner to claim compensation for the diminution in value of his/her property, plus the costs of removing the Knotweed from the affected land, and also an injunction preventing reinfestation or requiring the offending landowner to take action to control the Knotweed – as was requested by Mr and Mrs Smith in the case of Smith v. Line. 

The recent cases

The cases of Smith v. Line and, prior to that, Williams & Waistell v. Network Rail Infrastructure Ltd (the Waistell case), required the courts to consider common law nuisance.  Although the courts concluded that the mere presence of Knotweed on both Mr and Mrs Smith’s and Mr Waistell’s land amounted to an actionable nuisance before it actually caused any physical damage to either property – because the presence of Knotweed on the land had unlawfully interfered with the claimants’ use and enjoyment of their land by reducing the value of that land – this lack of physical damage meant their claims for nuisance based on encroachment failed.  This was because physical damage to property is key to the success of any claim for encroachment.

The claimants were both awarded damages to reflect the reduction in value of their land as a result of the unlawful interference, together with costs.  Mr Waistell was also awarded an additional sum to treat the Knotweed, Mr and Mrs Smith having already undertaken a programme of treatment works themselves.

Issues to consider

These cases act as a reminder of the potential criminal and civil liability for landowners whose land is the original ‘source’ of Knotweed. However, adjoining landowners should also consider the effect of that Knotweed on their land.  Not only could the value of their land be reduced, but it could also be less attractive to potential purchasers as a direct result – and more difficult to secure finance against!

Similarly, if an adjoining landowner does bring an action in nuisance for damages based on this reduction in value, they would be well advised to seek an injunction requiring the offending landowner to carry out a course of treatment works.  Otherwise, any damages awarded would be calculated on the assumption that such treatment works would be carried out, when in fact there is no requirement for the offending landowner to do anything.

Finally, the fact that there has to be physical damage to succeed in a claim for encroachment could mean that landowners are forced to wait before commencing proceedings.  This ‘wait and see’ approach could open the door for landowners to start arguing about where the original source of the Knotweed was altogether!

Network Rail were granted leave to appeal the judge’s decision in the Waistell case, so we await an update on the law of nuisance once the Court of Appeal has heard the case later this year.

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