The Royal Institution of Chartered Surveyors (RICS) Guidance Note published in January 2022, on which our Director Ben Lindley is directly named as a contributor set the standard by which Japanese knotweed is controlled. The RICS’ Standard was governed and overseen by the Standards and Regulation Board (SRB), whose aim is to develop the ethical and competence of the profession and set standards for service delivery.
The new Note was later superseded by a new document that was reissued in October 2022 as a Professional Standard, however the principals outlined in the document remained the same.
The RICS information paper 2012 established a framework for assessing the risk to residential property posed by Japanese knotweed. It specified four risk categories (1-4), using a distance of 7m from buildings and boundaries as the defining measurement. Along with asking for an assessment on minor or major structural damage. The information paper was instrumental in providing a rationale that enabled lending on residential properties impacted by knotweed.
Since the original information paper was published in 2012, academic research into Japanese knotweed has been published that has influenced a review of property impact guidance and development of the new Guidance Note.
In 2018 a research paper by Fennell et al from the University of Leeds reported that typical rhizome spread was 3m, opening consideration for a different defining distance measurement to 7m. The paper also reported that cases of material damage to a structure were only likely when knotweed was immediately adjacent to susceptible structures.
A further research project by Jones et al from the University of Swansea published findings in 2018 on the optimum method of controlling Japanese knotweed with herbicides. Control of an infestation was readily achievable when properly undertaken. However, fast results or total eradication were not recognised as readily attainable from herbicide only treatment methodologies.
In 2019, the House of Commons Science and Technology Committee published a report on an enquiry titled ‘Japanese knotweed and the built environment’. The enquiry had been promoted by the publication of the research papers and a growing litigation industry surrounding knotweed.
Japanese Knotweed Ltd provided written evidence to assist with the enquiry, and a company Director, Ben Lindley, was invited to provide oral evidence at the committee meeting, along with seven other industry stakeholders.
The Technology Committee report made recommendations, one of which was for the RICS to review its guidance on knotweed. The report described the ‘7m rule’ as a blunt instrument that did not reflect the latest scientific evidence. It called for a revised assessment process which was ‘much more nuanced and evidence-based … to reflect the latest thinking on the significance of Japanese knotweed’.
The RICS Guidance Note “Japanese Knotweed and Residential Property” 2022, is the result of the requested re-assessment.
What are the main changes?
The RICS Guidance Note provides an updated assessment for RICS members in conducting their surveys and valuations.
The guidance takes onboard previously published research into Japanese knotweed. Modifying the associated property impact assessment, which advises lenders on needing to apply mortgage retention or not.
When advising for non-lending purposes the property surveyor will always advise the client to seek advice from a specialist remediation contractor about the Japanese knotweed.
The contractors’ trade association (the PCA Invasive Weeds Control Group) have produced a more detailed assessment of impact and remediation recommendations in their associated Guidance Note ‘Japanese Knotweed – Guidance for Professional Valuers and Surveyors’.
A specialist remediation contractor, such as Japanese Knotweed Ltd, will advise clients of the specific impact knotweed may have on a property, such as loss of free use, maintenance restrictions, limitations on development, waste disposal costs, and potential litigation impacts.
A specialist remediation contractor will recommend the appropriate remedial action to take, such as herbicide treatment or excavation under a Knotweed Management Plan for any property affected by knotweed and offer the provision of an Insurance Backed Guarantee.
So, ‘Caveat emptor’ buyer beware and as advised by the RICS Guidance Note management categories, always seek advice from a specialist remediation contractor, such as Japanese Knotweed Ltd, when looking to sell or buy property impacted by Japanese knotweed.