Getting to the root of weed problem

Japanese Knotweed
Japanese Knotweed

RICS has launched the country’s first cross-industry approved advice on
Japanese Knotweed to
encourage banks to lend on homes across the North West affected by the 
notorious foreign plant.

The plant, which originates from Japan, can grow up to three meters in height in just ten weeks – taller than a British red telephone box.

It is renowned for causing problems for homeowners, with many vendors unable to sell their property as lenders are reluctant to provide loans on homes affected by Japanese Knotweed, despite it being treatable and rarely causing severe damage to a property.

The RICS Japanese knotweed information paper, which is supported by the Council of Mortgage Lenders and the Building Society Association, has been published to help lenders and surveyors accurately assess the risk caused by Knotweed and sets out clear advice on how to identify, assess and treat it.

The guidance has categorised the extent of the risk into four classifications, with tier one being the lowest; when the plant is seven meters or more away from the property.

This will help to ensure consistent assessment and reporting of the plant to banks and enable lenders to establish a clear lending policy for loan applicants.

Philip Santo of RICS Residential Professional Group says: “There is a real lack of information and understanding of what Japanese Knotweed is and the actual damage it can cause.

“Without actual advice and guidance, surveyors have been unsure of how to assess the risk of Japanese Knotweed, which can result in inconsistent reporting of the plant in mortgage valuations.”

RICS North West Residential spokesperson, Ian Perry of Your Housing adds: “It is essential to encourage lending to keep the region’s housing market moving, and this RICS guidance will provide the experts with the tools they need to make accurate decisions on the real impact of Japanese Knotweed and if and how much finance can be offered to applicants.”

It is not against the law for landowners to have Japanese Knotweed on their property. However, if it can be shown that the plant has spread from their property onto another property, then they could be considered liable for any damage caused.

If Japanese Knotweed is observed on an adjacent property, RICS recommend working in partnership with your neighbour to tackle the problem. Japanese Knotweed can be eradicated by hiring dedicated contractors who treat the plant with phosphate.

But with roots as deep as three meters, it can take several treatments and up to two years to kill it effectively.

In the case of a neighbouring landowner not cooperating, take legal advice. In some cases it might be advisable to contact the relevant authority (e.g. Police Wildlife Crime Officer, Environment Agency, etc).

l For more information on Japanese Knotweed or a copy of the RICS Japanese knotweed information paper visit