The Environment Agency describe it as “indisputably the UK’s most destructive, aggressive and invasive plant”. Clearly a dangerous species, but a recent study showed that less than a fifth of Brits that were aware of Japanese knotweed could actually identify it from a list of photographs.

Japanese knotweed removal firm Environet, who commissioned the survey undertaken by YouGov, said this lack of knowledge was a concern for homeowners or anyone letting, buying or selling a property as it puts them at risk.

They claim the invasive, non-native species can damage building structures, making them unsellable without a treatment plan in place. Most mortgage lenders will want to know if the plant can be controlled or eventually eradicated before agreeing to a mortgage loan. Homeowners could even be sued by neighbours if they allow the knotweed to spread.

Clear Laws – Land Owners Must Pay if Knotweed Threatens Other Property

At the start of July 2018 a court of appeal ruled that the respective owners of two bungalows in south Wales were entitled to damages from Network Rail. The rail transport company owns the land behind the properties where the plant has been present for at least 50 years. The knotweed’s rhizomes (underground shoots) had extended beneath both of their properties and despite challenging the decision, Network Rail had to pay the claimants £15,000.

It’s being labelled as a landmark ruling. The judge, Sir Terence Etherton, said the homeowners would not be entitled to seek damages on the grounds that the knotweed had reduced the value of their properties.

He clarified that their case constitutes a nuisance and for a nuisance claim to succeed, it was not necessary to prove physical damage to the property. Just the fact that knotweed rhizomes are present on the land constitutes an interference with its amenity (the right to use and enjoy it).

This judgement will have far-reaching implications and is expected to increase the number of claims being made against land owners with Japanese knotweed on their property.

But is it really a major threat to property and building structures?

Knot Such a Big Problem for the Property Industry

Ecologists can find no evidence Japanese knotweed causes significant structural damage.

This is according to new research published in July 2018 carried out by Leeds University and global engineering firm AECOM. The extensive study is the biggest of its kind to date assessing the impact of Fallopia japonica on properties.

They looked at 68 residential properties where knotweed was found and analysed another 81 sites where the plant had been excavated. It also surveyed 51 invasive species control contractors and 71 property surveyors while studying previous research.

The findings of the data and surveys were groundbreaking (but not house-breaking) because it showed that reports of defects or structural damage to residential properties were in fact rare.

Contractors’ records of 81 excavations showed that Japanese knotweed rhizomes rarely extended more than 4m from above-ground plants and their spread was generally less than 2.5m. The researchers found it was less likely to cause damage than many other common species like trees, climbers and shrubs (such as buddleia).

Gareth John, Managing Director of AgentPro estate agent software, described the study as welcome news for the property industry.

“It will be interesting to see how mortgage lenders react to this new study. The UK needs to get property sales moving again, and this research myth-busts one of the major hindrances sellers encounter, so I’m sure estate agents will welcome this research with open arms.”

Weed Out the Doubts and Complacency

The legislation still exists in the UK, under the Wildlife and Countryside Act 1981 (amended in 2010) the Environmental Protection Act 1990 and the Anti-social Behaviour, Crime and Policing Act 2014. They can all be used to prosecute those failing to control Japanese knotweed or who cause it to spread into the wild.

When thinking about a property inventory, gardens can be overlooked. Inventories aren’t just about furnishings, but a good report will include photographs and details on the property’s condition, cleanliness and the garden too. A garden can become untidy during a tenancy so before and after evidence in a report can be crucial. Don’t cut corners as well as weeds, book a professional clerk to handle your inventory needs and contact Assist Inventories to find out about their expert services.