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17 May 2019 < Back

Japanese Knotweed and its Impact – Science & Tech Committee Report

 The long-awaited report following the Science and Technology Committees session into Japanese knotweed and its impact on homes, mortgages and the built environment has finally been released.

In many respects, we are pleased to say, the report is reasonably balanced. From a Property Care Association perspective, it puts the Association and the work of our Invasive Weed group members in good light and shows ourselves as one the leading ‘voices of authority’ on Japanese Knotweed based on our input already and also on the impact we can make on steering some of the suggested recommendations.

Just a small ‘heads up’ before you hit the ‘Download Button’. The report is 42 pages long. If you are short on time, just check out our summary below.


What the Science and Technology Committee recommends

The Science and Technology Committee report advises that the latest research into Japanese Knotweed suggests that the physical damage to property is no greater than that of other disruptive plants and trees. However, other plants and trees are not subject to the same levels of control and do not have the same impact on the sale of a property.

What is recognised within the report however, is the difficulty to manage and treat Japanese knotweed compared to other flora and fauna and the general requirement of multi-year treatment plans using specialist herbicide or excavation, especially with Japanese Knotweed’s ability to remain dormant for a number of years even with the presence of chemical treatment.

Conclusion of the Science & Tech committee on Japanese Knotweed

In terms of the conclusion and recommendations, there were two main headline points:

  1. The research to base the report on
  2. Existing RICS framework to Japanese Knotweed

1. The research to base the report on

In terms of the physical effects of Japanese Knotweed on property, the report found very little academic research to refer to, despite the impact knotweed can have on the sale of a property. To resolve this:

  • The Environment Agency has been requested to approach the ‘Department for Environment, Food & Rural Affairs’ (Defra) as well as others to action this research to fill the knowledge gaps.
  • Environment Agency to organise a meeting with major national Japanese knotweed remediation firms to consider if a national database could be created from the above research and if companies themselves can contribute to this to seeks a to better understand Japanese knotweed for all.
  • As European countries seem to have a different attitude to Japanese Knotweed, Defra to conduct research as to why there is a different attitude and approach to Japanese knotweed in terms of property sales. Report to be finished by the end of the year.

2. Existing RICS framework to Japanese Knotweed

Regarding the current RICS Framework, it was clear is ‘out of touch’ with the Committee quoting: “the ‘seven-metre rule’ that forms part of the 2012 risk assessment framework is being used as a blunt instrument in some mortgage lending decisions“.

The report advised that a new evidence-based risk framework is urgently needed to reflect the latest thinking on the significance of Japanese knotweed and to better measure the potential risk on a case by case basis. To resolve this:

  • RICS has had a meeting(s) with key stakeholders, the PCA, and other influencers to update its 2012 assessment framework for Japanese knotweed. This is to be completed as soon as possible and certainly no later than the end of this year.
  • In terms of the Property Information Forms, the ‘Law Society’ in consultation with the RICS, is to review the wording of the questions in relation to Japanese Knotweed.

What the PCA is doing to help on Japanese Knotweed

In terms of what your Association is doing, we have been working very work behind the scenes prior to and now very much upon the Science and Technology Committee recommendations. PCA is now working in partnership with the Royal Institution of Chartered Surveyor (RICS), Environmental Agency and others to improve and update the guidance and research on Japanese Knotweed.

We are also working with ‘NetworkRail’ to assist with Insurance guarantees with properties affected by Knotweed near railway lines and also helping academics and institutions to research new and improved ways through both involvement and funding how we can better manage the treat the Knotweed issue.

To all our Invasive Weed members, please rest assured that we are working hard for you. We have not been a bystander. We are highly involved and in the mix with a solution!
Watch this space and follow our Social Channels to keep in the loop with the next update…



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