Japanese knotweed on UK properties: lenders “overly cautious”

japanese knotweed on uk properties
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A government committee has found that the UK’s current approach to Japanese knotweed is “overly cautious”, particularly with regard to mortgage lending.

The Science and Technology House of Commons Select Committee, which has been conducting a wide-ranging inquiry into the effects of Japanese knotweed on the UK’s built environment and the science underpinning current regulation, concluded today that more academic research is warranted and that current rules and protocols governing growth of Japanese knotweed on UK properties are “overly cautious”. The committee found that, while Japanese knotweed is no more damaging to its environment than other plants classified as “disruptive”, mortgage lenders were particularly reticent about the plant – significantly more so than lenders in other countries.

MPs advocated a more evidence-based approach to regulation and housing decisions pertaining to Japanese knotweed on UK properties; and called on the Department for the Environment, Food and Rural Affairs (DEFRA) to conduct an international study on the approaches of other countries to Japanese knotweed. They further expressed concern that the “seven-metre rule”, whereby properties with Japanese knotweed growing within seven metres of the property line may have difficulty obtaining mortgages, had been deployed as a “blunt instrument” rather than as a guideline.

Rt Hon Norman Lamb MP, Chair of the Science and Technology Committee, said: “The presence of Japanese knotweed can have a ‘chilling’ effect on the sale of a property. It is clear that the UK’s current approach to Japanese knotweed is more cautious than it needs to be, especially when comparing it to that of other countries. We need an evidence-based and nuanced approach to the issue, one that reassures owners and buyers that they will not be subject to disproportionate caution when trying to sell or buy a property.

“The current framework lacks a clear and comprehensive evidence base and yet is causing significant problems to some house vendors and purchasers. I am pleased that RICS [the Royal Institute of Chartered Surveyors] responded to the Select Committee hearing and has already started the process of updating its 2012 assessment framework. We hope to see this no later than the end of the year. At present resolving disputes between neighbours regarding land affected by Japanese knotweed is challenging and can be protracted. This challenge will be diminished if a more proportionate approach to Japanese knotweed is taken. However, until we reach this position there needs to be an emphasis on resolving disputes through mediation rather than litigation.”


  1. Japanese Knotweed
    As a Japanese Knotweed consultant for more than 17 years now retired
    It is more off a environmental issue than a construction issue
    Yes I have seen damage done to houses but these houses are old or geery built
    It has cost the building industry billions of pounds for what
    The big boys of Japanese Knotweed have put the fear of death to house builders,charter suyveors, artitects, and the pubic and charge an earth to eradicate this weed why
    Trees do more damage to building and also other weeds do more damage than Japanese Knotweed


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