Homeowners trapped by Japanese knotweed will soon be freed

·4-min read
japanese knotweed house prices - PA
japanese knotweed house prices - PA

Homeowners trapped in properties with Japanese knotweed could soon be freed under new guidance for property valuers.

For years, banks have refused to lend on homes where the fast-spreading invasive plant is found within seven metres of the building. Its presence can wipe up to 15pc off a property's price.

However, updated guidance published by the Royal Institution of Chartered Surveyors, an influential professional body, has scrapped this "seven metre rule" in favour of a more lenient approach.

The new advice, which comes into force in March, means surveyors assessing property on behalf of mortgage lenders do not need to flag Japanese knotweed as a risk, unless it is causing visible damage to a property.

It should mean that homeowners who have been hampered by box-ticking surveys that found the plant close to the property, but without it posing a threat to its structure, can now sell their home for the full value.

The invasive weed is estimated to affect up to 1.45 million homes across Britain, and is notorious as being highly destructive and difficult to kill. Last year Rics claimed the plant's reputation had been built upon "myths and misconceptions" and assured homeowners that its presence was not a "death sentence" for property sales.

Surveyors have now been advised by the professional body to only treat Japanese knotweed as a red flag if it has actually caused damage to a property, or threatens its value because it is so widespread in gardens that it impacts the owner's enjoyment of the land.

Rics said: "Substantial structures on sound foundations are unlikely to suffer structural damage due to Japanese knotweed.

"The so-called ‘seven metre rule’ focused more on...an overstated risk of Japanese knotweed to buildings, rather than its sometimes-serious impact on amenity."

It added that if knotweed is found where property is damaged, surveyors have been asked to be clear if it was the plant that caused the damage or whether it simply grew where a building was already in a "poor or defective condition".

Japanese knotweed lies dormant underground in winter months and grows in the summer in bamboo-like stems up to 3m (9.8ft).

Nic Seal, of Environet UK, an invasive plant specialist, said the new guidance was "cautious and sensible", but also recognised the "very real risk" the weed posed to homeowners.

"I'm pleased to see the focus is no longer only on the structure of the property and the risk of damage, which is rare, but also on amenity value – in other words, the effect of knotweed on the use and enjoyment of the garden," he said.

The Rics guidance recommends surveyors flag the plant's presence if it is visible within three metres of a property's boundary, such as in a neighbour's garden. But it advised this would have "limited impact" and should not affect mortgage lending.

Mr Seal said: "Cases where knotweed encroaches from a neighbour's garden are often much more costly and cause more aggravation than if the plant was on the seller's own property, because legal redress comes into play. A buyer needs to be aware if they are walking into that."

In 2019 a report by the House of Commons Science and Technology Committee warned that banks were adopting an "overly cautious" approach to the issue, even in cases where the invasive plant posed no practical threat.

MPs at the time warned mortgage lenders were relying on discredited scientific evidence and noted that European banks were far less risk-averse to lending on properties with the plant.

Japanese knotweed was first introduced to Britain in the 19th century and was popular with landscapers because of the speed and density with which it grew. The plant can also often be found close to railways because of its historic and widespread use to support tracks and embankments.

In recent years homeowners have been successful in bringing claims worth tens of thousands of pounds against Network Rail after knotweed spread from railway lines into their gardens. However, any future claims could be thrown into doubt if knotweed is no longer a detriment to property values.

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