By Jhoanna Alvarado (Paralegal)

In the recent unreported County Court case of Williams and Another v Network Rail Infrastructure Ltd 2017, Network Rail was held liable for their failure to take reasonable steps to prevent Japanese knotweed from blighting properties on neighbouring land.

What is Japanese knotweed?

Japanese knotweed is an invasive plant that can cause physical damage to buildings and land through its spreading roots, and is expensive and time-consuming to eradicate. It is a criminal offence to ignore an order to control Japanese knotweed, although not an offence to "have" it on your land where an order has not been made to stop or prevent it and there was no suggestion that a criminal offence had been committed in this case.

Facts

The claimants owned two semi-detached bungalows whose rear walls abutted a railway embankment and path. This embankment had been infested with knotweed for at least 50 years.

The claimants brought their case under private nuisance arguing the following:

  1. Encroachment – The claimants argued that the knotweed roots had encroached upon their land not only to the foundations but also under the bungalows themselves. They alleged no proof of damage was necessary in order to meet encroachment grounds. The court followed the principles set out in Delaware Mansions v Westminster City Council 2001 and concluded that as no visible damage to the foundations or the bungalows was identified, the grounds for encroachment were not met.
  2. Interference of quiet enjoyment/loss of amenity – The claimants alleged the presence of the knotweed interfered with their quiet enjoyment or amenity value of their properties. The court recognised that the amenity value of a property included the ability to dispose of it at market value.

The court considered the position of mortgage lenders who had, since 2012, refused to provide or granted limited mortgages where knotweed was within seven metres of the property's boundary. This was sufficient to demonstrate the diminution in the value of each property. Whilst in some cases involving a treatment-backed guarantee, a loan could be obtained, there remained residual diminution in value and this would affect the property's amenity value.

The court concluded that there had been constructive knowledge of the Japanese knotweed since at least 2012 and it had not been treated adequately.

Conclusion

Network Rail was ordered to pay damages to the claimants to cover a treatment package for the Japanese knotweed and for the residual diminution in the value of the properties. This case is of particular concern to the owners of sites where Japanese knotweed may be present, as its mere presence could result in substantial damages being awarded to the owners of adjoining third party properties.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.