Japanese knotweed can cause property owners numerous issues. From costly eradication works, to reducing the property value. We take a look at Japanese knotweed, and some recent cases involving knotweed on neighbouring land, and a professional negligence claim against a surveyor that did not spot the plant.

What is Japanese knotweed?

Japanese knotweed is a fast-growing plant, with bamboo-like stems. It can grow up to two metres tall and is very invasive. Its roots grow thick and deep, and can kill off all other plant life and cause damage to nearby buildings. Of course, there are other plants that can cause damage to property. However, and this is the crux of the issue, Japanese knotweed is very difficult to eradicate.

The plant is so invasive that it is a criminal offence to plant it in the wild. Further, if it is on your land, you must ensure that it does not become a problem to your neighbours. If it has a “detrimental effect of a persistent or continuing nature on the quality of life of those in the locality”, you could be prosecuted.

How can it affect my house?

The presence of Japanese knotweed can affect the attractiveness, and therefore the value of your property. For example, it can make developing the land more difficult, and, as we saw above, there is a risk of liability if it spreads to neigbouring land. Further, mortgage lenders tend to be cautious when dealing with Japanese knotweed and will require an eradication plan. If the knotweed is under seven metres away from the building, they may refuse to lend on the property altogether.

This being said, a recent report by the House of Commons Science and Technology Committee concluded that the current approach to Japanese knotweed is “overly cautious”. They have requested more research into the plant’s effects on structures and we will keep our blog updated on this.

Let’s look at some examples of how Japanese knotweed has affected property owners.

Williams v Network Rail Infrastructure Ltd

We looked at this case when it was first decided in the County Court. Since then, it has been appealed and heard at the Court of Appeal.

As we explained in our earlier blog post, this was a claim for nuisance. Two neighbours (Mr Williams and Mr Waistell) owned bungalows in South Wales, next to a railway embankment owned by Network Rail Infrastructure Limited (NRI). Knotweed had infested the embankment for many years, and it regularly spread on to the neighbours’ land. The neighbours brought a claim in nuisance, alleging that the plant had spread to the foundations of the properties and affected their ability to sell the properties.

The County Court decided that NRI had caused a nuisance by failing to take reasonably steps to prevent the knotweed from affecting the neighbours’ properties. NRI appealed against the County Court’s decision.

Court of Appeal

The Court of Appeal said that the County Court was wrong to find that the presence of Japanese knotweed was an actionable nuisance because it reduced the market value of the neighbours’ properties. The purpose of the law of nuisance was to protect the land owners’ use and enjoyment of the land; not to protect the value of property.

The Court of Appeal decided, however, that knotweed can be an actionable nuisance even before it causes physical damage to neighbouring land. Here, a nuisance was committed where the encroachment of the roots reduced the utility and amenity of the properties. There was no reason why, where appropriate, a claimant should not be able to obtain a final mandatory injunction where the amenity value of land was reduced by the presence of knotweed roots, even though there was no physical damage at the time.

Ryd v Conways Chartered Surveyors

Earlier this year, a County Court looked at a professional negligence claim against a surveyor who had failed to report on the existence of Japanese knotweed.

Mr Ryd was looking to purchase a £1.2 million flat in north London. Mr Ryd is partially sighted and instructed Conways Chartered Surveyors (“Conways”) to carry out a thorough survey as he was not able to inspect it properly himself.

Conways declared that the property was in “excellent condition both internally and externally”. However, it appears that knotweed was actually “visibly present and growing”. A year later, Mr Ryd’s gardener spotted the knotweed, and Mr Ryd began the lengthy process of eradicating it from his land. The eradication cost Mr Ryd £10,000 and caused immense disruption. Even after all that work, it came back a few years later. By this point, Mr Ryd had insurance to cover the possibility of it re-emerging. Mr Ryd sued Conways for failing to report the knotweed. He claimed for the reduction in value to the property as a result of the knotweed. The court found that Conways’ report did not reach the standard of a reasonably competent surveyor. The judge awarded Mr Ryd £50,000 in compensation.

We can assist with your Japanese knotweed issues: from buying or selling a house with knotweed; to dealing with knotweed encroaching from a neighbour’s land; and professional negligence claims against suveyors who have not advised you about the presence of knotweed. Call us on freephone 0800 988 7756 for a free initial chat.