19 November 2018
Japanese Knotweed - is there a risk to landowners?
The Environment Agency describes Japanese Knotweed as “indisputably the UK’s most aggressive, destructive and invasive plant”. A significant case passing through The Court of Appeal has meant that Japanese Knotweed continues to be in the news this year.
Lyn Dario has looked at the potential risk to landowners.
Why is it a problem?
The ENDS Report in October 2018 quoted Government figures that estimate invasive plant species (of which Japanese Knotweed is one) cost the UK economy around £1.8 billion every year. There are said to be 2,000 non-native species of which 10-15% are “invasive” - in other words, a pest that does not have a natural predator to keep it in check.
Opinion in recent months seems to have been split in terms of the severity of the risks from Japanese Knotweed. On the one hand, Environet UK has produced a report indicating that knotweed has wiped almost £20 billion off the value of the UK property market. The report concludes that based on data collated over the last 20 years, 4-5% of UK homes are either directly or indirectly affected by Japanese Knotweed, reducing the average house price in each case by around 10%. In addition, lenders are unlikely to provide funds for properties where there is a known Knotweed problem, whether on the land itself, or on property adjacent to it. Where lenders are prepared to advance funds, this will usually only be in cases where there is a Knotweed management plan, underwritten by an insurance guarantee.
On the other side of the coin, AECOM and the University of Leeds were rather more upbeat in their assessment of risk from Knotweed. Their report concluded that developers and landowners could afford to be rather more pragmatic when it comes to controlling Japanese Knotweed. In their opinion, Knotweed causes no more significant damage to buildings than other vegetation: and eradication should be prioritised in areas that are adjacent to residential properties – in other words, Knotweed should be managed on a risk-based basis in terms of where the most sensitive receptors are.
Network Rail Infrastructure Ltd v Williams and Waistell  EWCA CIV 1514
These reports pre-dated a significant appeal case on the subject of Knotweed.
In July this year, the Court of Appeal handed down a decision regarding whether two property owners could sue Network Rail for the presence of Japanese Knotweed on their land.
In this case, the two claimants owned bungalows that backed onto railway lines owned by Network Rail. The railway embankment had been overgrown with Knotweed for a number of years.
There are various statutory duties that apply to the control of Japanese Knotweed, including the Wildlife and Countryside Act 1981. Under the Environmental Protection Act, it is also regarded as special (i.e. particularly high-risk) waste, when being removed for disposal from a site. Its disposal has significant cost implications as a result.
The Claimants in this case, Mr Williams and Mr Waistell, argued that the presence of Japanese Knotweed constituted a nuisance and they sought an injunction forcing Network Rail to eradicate it from their properties.
The Judge who heard the case in the High Court declined to grant an injunction but awarded damages instead. He mentioned the restrictions on funding to purchase land affected by Knotweed, and concluded that the value of both properties had been diminished, and therefore that the owners should receive compensation.
Network Rail appealed on the basis that diminution in the value of a property was pure economic loss, and that it could not, therefore, give rise to a claim in nuisance.
What was the outcome?
The Court of Appeal upheld the Judge’s decision, but gave different reasons for so doing. In the leading judgement, the Court of Appeal confirmed that the test for a claim to be brought in nuisance, is whether the act complained of interferes with an owner’s use and enjoyment of their land; and not simply because it leads to a reduction in value of the property. It is to be regarded as a ‘property’ tort, arising as a facet of property ownership. It was not necessary to show that the Japanese Knotweed had caused actual physical damage for the Claimants to succeed in their action against Network Rail.
The Court concluded that the Japanese Knotweed was:
“…a classic example of an interference with the amenity value of the land.”
The Court took into account the fact that Mr Williams and Mr Waistell would face constraints, by dint of the presence of the Knotweed, if they wanted to extend or develop their properties. In particular, its being treated as special waste would mean significant extra cost for disposal of the Knotweed. This was an interference with the use and enjoyment of their property; and for these reasons, the Judge’s decision was upheld, and the Claimants were able to recover damages.
The damages in this case only amounted to around £31,000, but if the Environet UK report is correct, and 4% to 5% of UK homes are affected by Japanese Knotweed, the ultimate bill for landowners whose property is the source of Knotweed could be huge.
ENDS also reported in September 2018 that Bournemouth Borough Council had incurred around £150,000 in clearing Japanese Knotweed from a site so that a development of affordable homes could proceed. This demonstrates that the cost of eradication can be a significant burden.
What if there is Knotweed on my property?
It is worth bearing in mind the advice given by AECOM and the University of Leeds. Landowners with land holdings contaminated with Japanese Knotweed, but who have no immediate plans to redevelop, should simply try to manage the spread of the plant, and should concentrate efforts and resources particularly on areas where the Knotweed may be at increased risk of spreading to neighbouring property.
Of course, if the land is to be redeveloped, Knotweed is a site constraint, and the costs of management or eradication over a number of years, need to be factored in to the project costs.
In the first instance it is beneficial to take specialist advice as to the potential impact based on your specific property and redevelopment plans. The impact can then be assessed and associated costs and timings can be built into planning.
For more information, contact Lyn Dario.