Japanese Knotweed… What damage could a plant possibly do?   

What is Japanese Knotweed?

Japanese Knotweed is an invasive and resilient weed.  Its rhizomes and roots can spread a considerable depth underground.

Japanese Knotweed is known to block drains, grow in between slabs and affect concrete movement joints in driveways and disrupt brick paving.

The impact Japanese Knotweed can have on a property:

Damage to building and land – This can result in a decrease in property value, increased insurance premiums and can impact on the ability to get a mortgage as well as deter future buyers.

Financial burden and time consuming – The removal, treatment and disposal of Japanese Knotweed is costly as it will need to be done professionally and over a lengthy period of time.

Enforcement – A Local Authority can serve notice where a landowner does not control the spread of Japanese Knotweed to remedy the situation if adjoining area is adversely affected.

Changes in legislation

The Royal Institution of Chartered Surveyors (RICS) updated its guidance notes on Japanese Knotweed as of the 23 March 2022. Some of those changes include:

  • Mortgage Valuers – The assessment process is 3 metres distance beyond a boundary rather than 7 metres.
  • Surveyors – Can now use their use their professional judgement to determine how much of the property is at risk of damage from the weed. Surveyors are also only responsible to report Japanese knotweed if it is clearly visible on inspection.
  • Homeowners – Are now only responsible for Japanese Knotweed that is 3 metres outside of their property boundary. Japanese knotweed is more visible at certain times of the year and may not be reported by a surveyor if it is not clearly visible during a particular inspection.
  • Lenders – There are now four ways to categorise Japanese Knotweed – Management Categories A – D. Under categories “A or B most lenders are expected to impose retentions on mortgage advances pending receipt of a remediation specialist report”.

If this is a situation you find yourself in the Property team at Woodfines can help you navigate through the conveyancing process.


Melanya Ponraj

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