The Management of Japanese knotweed

February, 2023

The Management of Japanese knotweed

In recent years various industry bodies have changed their stance on the potential threat of Japanese knotweed. For example, The Royal Institute of Chartered Surveyors updated its guidance earlier this year saying the risk posed is now understood to be much less than originally thought.

By way of some background knotweed is a native species to Japan where it is freely found growing on the sides of volcanoes. It was imported into England in the mid-19th Century. The striking plant proved popular with Victorians and was planted widely in parks and gardens, but also spread of its own accord along railways and inland waterways. The plants invasiveness was noted as far back as 1898 with this view becoming more mainstream in the seventies. However, knotweed remained on sale in nurseries until around 1990 and it was only this century that property surveyors and mortgage lenders starting taking a hard-line view on the invasive plant, but the science has started to shift.

Research now finds that more damage is caused to property by trees as well as woody plants such as ivy and buddleja. We know now that Japanese knotweed may damage lightweight structures but rarely affects foundations or walls. There is an increasing recognition that much public fear of knotweed is based on unsubstantiated myths and misconceptions. It is now known that it does not destroy houses or grow through solid concrete.

Knotweed is most visible between March and November and is distinctive in its appearance assuming you know what to look for. The tell-tale signs are the shield shaped leaves and bamboo-like stems with purple freckles in early springtime. In late summer small cream flowers appear and the stems darken to a deeper brown colour before the plant becomes dormant in winter.

The plant can be successfully managed over the long term by a competent specialist. Nevertheless, sellers must always declare the existence of the weed on their property via a TA6 Property Information Form provided by lawyers during transactions.

Britain’s largest building society Nationwide, says if knotweed is causing material damage to a buildings structure, or is visible near the property then it requires borrowers to put a treatment plan in place with an insurance backed five year warranty.

According to many mortgage brokers the presence of knotweed can cause obvious concerns but many high street lenders will still consider a mortgage for a property. Consequently, Japanese knotweed is no longer the mortgage lending nemesis it was once thought to be.

If you are looking to buy or sell a property in 2023 and wish to register with us, we would be pleased to hear from you with your specific requirements. Telephone 01608 801030 or email in the first instance.