Gardeners and Conveyancers Beware: Japanese Knotweed

In this article, Paul Butt considers the impact of Japanese Knotweed on property and issues a warning to both conveyancers and homeowners alike.


One of the many non-property law issues that Today’s Conveyancer must be familiar with is that of Japanese Knotweed. It has been receiving increased publicity of late – see e.g. Today’s Conveyancer of 16th March 2017 and 26th May 2017. These articles are essential reading for any conveyancer – whether residential or commercial – Knotweed does not affect only houses! They also really ought to be read by all property owners – for how many of us could actually recognise Knotweed if we saw it? And, of course, it is a standard question on the Law Society’s Property Information Form which we expect all house sellers to answer. Should we be advising clients who don’t know what it looks like to answer ‘Don’t Know’ to this question? Would not being able to recognise it be a good defence to a misrepresentation claim if the buyer discovers it was on the land at exchange and the seller had replied ‘No’ to the question?

And a recent court case (see Today’s Conveyancer 13th February 2017), deserves further consideration as it shows that all the concerns expressed about the impact of Knotweed on land owners are not just scare stories put about by those in the business of removing it. It can – and does – reduce the value of houses by 50%. The case also shows that property owners with the plant on their land may find themselves liable to neighbouring owners even though it has not encroached onto that neighbouring land.


The case is only a County Court case (and so not of binding authority) but is indicative of the way the courts are moving. In the case, a homeowner (and his neighbour) in South Wales sued Network Rail in relation to Japanese Knotweed on an embankment at the rear of their properties. Mr Waistell wished to sell his bungalow and relocate to Spain but discovered that no lender would lend on his property because of the 600 square metres of Knotweed on the embankment. Eventually court proceedings were commenced after Network Rail failed to effectively treat the Knotweed. Apparently, it had been there for 50 years!

The claim was brought in the tort of private nuisance on the basis that the Knotweed was “causing a substantial and unreasonable interference with the claimant’s land, his use or enjoyment of that land”.  The claimants asserted that Network Rail was liable for the knotweed’s encroachment onto their land and more significantly that the mere presence of the knotweed on the defendant’s adjoining land was itself a nuisance as it affected the claimants’ ability to sell the property at market value.

While the claimants failed to prove their case on their first ground due to a lack of evidence of damage to the bungalows due to the encroachment, the judge, Recorder Andrew Grubb sitting in Cardiff County Court, after a four day hearing, did find in favour of the claimants on their second ground. He found that the presence of the knotweed had devalued the claimants’ property and even if treatment took place, the sale value would still be below the market value. Even though there was no physical damage and no effect on the utility of the land, the Court found that the amenity value of a property is not simply the use and enjoyment of the land, but can include the ability to dispose of it at a proper value. He rejected this as being equivalent to pure economic loss – which is generally not recoverable in actions in tort. The Court also found that the defendant had constructive knowledge of the risk of knotweed spreading to neighbouring properties following the publication of materials by the Royal Institute of Chartered Surveyors and the Property Care Association in 2012. The Judge ordered Network Rail to pay £4,320 each to Mr Waistell and his neighbour to treat the knotweed and a further £10,000 each in compensation for the fall in value of their homes. Apparently, Mr Waistell’s bungalow, which was previously worth £135,000, is now valued at £69,000. And in case you are thinking that £10,000 is not adequate compensation on these facts, the judge stressed that the amount awarded was on the basis that the remediation work was carried out; if Network Rail fail to get rid of the knotweed, Mr Waistell could return to court and claim for the full drop in the value of his home.


So a warning to all property owners, both as to how knotweed can destroy property values even though it is not on your own land – and as to how failing to remove Knotweed when it is on your land can have expensive consequences. Some conveyancing firms, I know, issue explanatory notes on Japanese Knotweed to clients. These will now need amending to incorporate these latest developments. And should we consider, as part of our duty to our buyer clients,  raising a further enquiry of sellers as to whether Japanese Knotweed is present on adjoining properties? Oh dear, but then what about the Law Society’s Conveyancing Straightjacket – sorry Protocol?

Today's Conveyancer