Japanese Knotweed

Homeowners are given new hope in the fight against Japanese Knotweed

Along with “subsidence” and “damp”, the mention of Japanese Knotweed may make any homeowner or landlord’s heart sink.

Brought to the UK in the mid-19th century by explorer Philipp Franz von Siebold, who found it growing on the side of a volcano, Japanese Knotweed was so admired for its beauty that it was named the “most interesting new ornamental plant of the year” by the Society of Agriculture and Horticulture at Utrecht in Holland in 1847.

Little did we know back then, as the Royal Botanic Gardens in Edinburgh flogged the plant to nurseries, this exquisite bamboo-like plant would usurp ivy as the fast-growing scourge of gardens around the country.

Like ivy on steroids, Japanese Knotweed can work its way into walls, with foundation-ravaging roots which can grow up to three meters in depth and seven meters in any direction.

Naturally, this causes some problems for properties – £170million worth a year of problems to be precise – and has since been demoted from its flattering accolade from two centuries ago and placed on the World Conservation Union’s “worst invasive species” list. Ouch.

Knotweed and property owners

In previous years, property owners with Japanese Knotweed on their property found it difficult to sell their property – with the invasive plant wiping 15% off the property’s value. However, new guidance set by the Royal Institution of Chartered Surveyors (RICS) could help tackle this.

The group has abolished their previous seven-metre rule for a much more lenient approach, allowing surveyors to take a much more discretionary approach to the plant.

Since this guidance was first set out, they now have a much better understanding of Japanese Knotweed and it’s clear that there was an overstated risk to buildings. Research has since shown us that it causes minimal to no damage to substantial foundations but rather poses a threat to flimsier structures such as conservatories.

What does this mean for mortgages and insurance? 

Despite the updated guidance, mortgage lenders have been slow to react to this and many still require specialist reports and for the owners to implement costly eradication plans. Most insurers won’t cover damage caused by Japanese Knotweed as part of a standard Buildings Insurance plan but having it on your property won’t affect your cover in other ways.

However, that’s not to say that change isn’t on the horizon. Now that we have a clearer understanding of the way the plant behaves, lenders and insurers may change their position in the future. Even now, some insurers have started to offer specialised cover for Japanese Knotweed related risks.

If you’re worried about the Japanese Knotweed on your property or want to talk about other specialised risks that you require cover for, please do get in touch with Aldium4Care on 0151 353 3880