Awareness of Japanese knotweed is growing and so are disputes with neighbours when this invasive plant spreads across boundaries. It isn’t illegal to have Japanese knotweed growing on your land, but if you allow it to encroach onto a neighbouring property then you could be sued for the cost of treatment and, more importantly, diminution which could represent, on average 10% of the property’s value. 

So, what is the right approach if you notice Japanese knotweed growing in your neighbour’s garden? The first thing to do, is talk to them. They may not even realise they have a problem and be grateful to you for alerting them. If they ignore it however, what next? 

In our recent annual survey with YouGov, 42% of people said that if their neighbour failed to act they would contact their local council in the first instance. With legislation at their disposal aimed at preventing unreasonable behaviour that is having a negative impact on the local community’s quality of life, the local council may be prepared to issue them with a warning followed by a Community Protection Notice, forcing them to deal with the knotweed or face a criminal prosecution. In December 2018, Bristol City Council successfully used ASBO legislation to prosecute a landowner who allowed Japanese knotweed to encroach into the gardens of seven neighbouring homes.

A further 16% of those surveyed said they would contact their building insurer, but most buildings insurers don’t tend to cover damage caused by Japanese knotweed, and anyway, homeowners want the problem tackled before the structure of their home is threatened.

While 13% said they would take immediate legal action through court proceedings, this is usually a last resort for most people, when all the above have failed. You may wish to instruct a legal firm specialising in dealing with Japanese knotweed encroachment claims, who could seek compensation for the cost of treatment, legal fees, stress and diminution of property value. 

You’ll need to be able to prove that the knotweed has encroached from your neighbour’s land to yours. A word of warning, the direction of spread is not always obvious by above-ground inspection. In a recent case we were able to demonstrate that the knotweed spread was in fact opposite to the claim, i.e. originating from the claimant’s property, resulting in the case being rapidly dropped but with large legal fees borne by the claimant.

We’re experts at dealing with Japanese knotweed encroachment and are regularly called upon to give expert opinions in court, so please feel free to contact us for some friendly advice in the first instance.