The Royal Institution of Chartered Surveyors (RICS) new Guidance Note “Japanese knotweed and Residential Property” has been published on the RICS website. Implementation and use of the Guidance Note will commence from the 23rd March 2022.
This Guidance Note replaces the RICS Information Paper 2012 “Japanese Knotweed and residential property” including the widely referred to knotweed risk assessment categorisation. In this article we explain why, and what this means.
Why has new knotweed guidance been published?
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 released 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 at 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 structural damage were only likely when knotweed was immediate adjacent in very close proximity to susceptible structures.
A further research project by Jones et al at 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 7 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.
Who is the guidance intended for?
Primarily the Guidance Note is for the use of RICS members, and only applies to residential practitioners and residential property assessments (not commercial property or land).
It provides registered surveyors with an assessment guide to provide an initial evaluation of Japanese knotweed impact if found while undertaking valuations or surveys. It facilitates initial advice to be provided for pre-purchase and mortgage lending purposes.
If Japanese knotweed is found affecting the property, the client will always be advised (as documented in the Guidance Note) to seek advice from a specialist knotweed remediation contractor (such a Japanese Knotweed Ltd) on an appropriate course of management.
More detailed information about the identification and remediation of Japanese knotweed can be found in the publication by the Property Care Association’s (PCA) Guidance Note “Japanese knotweed: Guidance for Professional Valuers and Surveyors”, which deals with these important subjects.
Ben Lindley of Japanese Knotweed Ltd assisted the PCA Technical Manager in writing their guidance note, and we were happy to help in supplying the sample site plans and photos used in the publication.
Due the invasive nature of the plant, control costs, the problematic issues of disposing of knotweed waste, legal obligations, and litigations concerns, if a property is affected by knotweed a Knotweed Management Plan will be recommended. A property is classed as affected by knotweed if there is knotweed anywhere within the property boundary or within 3m of the property boundary if located off site.
What are the main changes in the new RICS Guidance assessment?
The new guidance is for use by property surveyors to initially assess knotweed impact for the purpose of property lending assessments.
It requires the property surveyor only to observe and assess the visible above-ground elements of the plant. Where they are situated on or in proximity to the property, and if any material damage to structures is being caused.
It does not explore in detail the way that knotweed may impact the property owner/occupier in day-to-day and long-term use of the property. This is a separate assessment that a specialist remediation contractor will make upon instruction from the client. For example, a property surveyor will not consider in detail issues of any underground rhizome spread, whereas a specialist remediation contractor will (considering restrictions on property use that rhizome areas may have for the owner/occupier).
Below are the main differences between the outgoing information paper and the new Guidance Note:
Management Categories, instead of Risk Categories
The (outgoing) information paper provided an assessment with 4 risk categories, 1 to 4 (with number 4 being the most severe). The incoming guidance note provides an assessment with 4 ‘management’ categories, A to D (with type A being the most severe).
Distance to habitable space - removed
The distance of a stand of knotweed to the subject property’s habitable space or ancillary structures of significant value (e.g. garage) does not affect the new management categories (as it did the outgoing risk categories). Japanese Knotweed Ltd will advise its clients that if knotweed is within 1m of suspectable structures the likelihood of material damage to structures occurring increases to -25-30% (based on analysis of surveying results and supported by academic research).
Consideration of a rhizome zone - mostly removed
Previously the 7m distance rule created a rhizome risk zone area around the visible extent of the plant. Rather than this being reduced to a 3m zone, the new assessment primarily looks at the area of the visible growth (apart from when assessing off site knotweed encroachment risks, where a 3m rhizome zone is applied into the assessment).
Specialist remediation contractors will advise their clients of likely impacts relating to 3m zone where underground rhizome may be present, often within a few centimetres of ground level.
Distance of off-site knotweed to the boundary - reduced
The distance at which an off-site stand of knotweed has an effect on the subject property assessed management category has been reduced down to 3m, from 7m.
An assessment on the impact of amenity use - introduced
The Guidance Note assessment now includes observations on knotweed impact to amenity space. This is an important addition, which starts to recognise the amenity use and cost implications that knotweed can bear upon using, maintaining, and changing/developing infested ground.
Property lending advice based on severity of impact - introduced
As alluded to the new Guidance Note is primarily aimed at advising lenders of the associated risks to lending. Each management category has advice to lenders including an indication as to whether mortgage retention is required or not.
The new Japanese Knotweed Management Category Assessments are:
- Management Category A - The knotweed is on site, record as actually causing visible material damage to structures. Lending advice = No mortgage until a specialist report is obtained and a suitable remedial plan is agreed. Non-Lending advice = Specialist Remediation Contractor to advise appropriate action.
- Management Category B - The knotweed is on site, not causing material damage to structures but likely to prevent use of or restrict access to amenity space. Lending advice = No mortgage until a specialist report is obtained and a suitable remedial plan is agreed. Non-Lending advice = Specialist Remediation Contractor to advise appropriate action.
- Management Category C - The knotweed is on site, not causing material damage to structures and not affecting access to or use of amenity space. Lending advice = No mortgage retention. Non-Lending advice = Specialist Remediation Contractor to advise appropriate management.
- Management Category D - The knotweed is off site within 3m of the subject property boundary. Lending advice = No mortgage retention except in exceptional circumstances. Non-Lending advice = Specialist Remediation Contractor to advise on possible encroachment and appropriate management.
You only need to know the RICS Guidance Note Management Category rating for a property if you are looking to buy or sell the property or re-mortgage it.
If you have previously received a RICS knotweed risk category 1-4 for your property this will be revised to a new ‘management’ category only when required - as above.
The RICS management category provided by an RICS surveyor may only influence the decision of the mortgage provider as to whether they will provide lending before or after the intervention of a specialist remedial contractor to manage the knotweed problem.
If knotweed is found anywhere within the boundaries of the property, or even within 3m of the boundary if located off-site, you should seek (as advised by the RICS) a survey and guidance from a specialist remediation contractor (such as Japanese Knotweed Ltd).
They will advise you of the specific impacts the knotweed will and may have on the free use, maintenance, and development of the site. This includes risks associated to disturbance of the infested ground spreading the plant, and difficulties and cost involved with disposing of knotweed waste. They will also provide guidance on legal implications such as the encroachment of knotweed to or from the property (which is an actionable private nuisance).
A specialist remediation contractor may not and does not need to provide an RICS management categorisation themselves as they do not advise on lending.
The contractor will advise the practical impact and recommend where necessary a treatment or removal programme, under the provision of a Knotweed Management Plan.
A PCA registered contractor (such as Japanese Knotweed Ltd) can then also provide an Insurance Backed Guarantee (IBG) on their works. Where required lenders may wish to see remedial works supported by a 5-year or 10-year IBG term to facilitate lending.
The invasive nature, amenity use impact, and associated costs of dealing with Japanese knotweed should not be ignored!
The new guidance does introduce some assessment subjectivity.
The new Guidance Note does introduce some subjectivity in the assessment required to arrive at a management category rating. Whereas the (outgoing) Information Paper simply used a distance metric (7m), the new ‘management’ categories assess two subjective matters: (1) causing structural damage and (2) amenity space impact.
Practitioners are advised to answer ‘No’ (not an impact to management level A) if they do not deem knotweed to be causing observed material damage to structures. It is not completely clear however if this includes the knotweed exacerbating existing damage. This is an important observation, as uncontrolled knotweed has the potential to exploit and worsen existing structural weaknesses and damage. Specialist remediation contracts will always recommend immediate action in either case to prevent a worsening situation.
Practitioners are asked if knotweed is likely to prevent the use of, or restrict access to, amenity space. The definition of the term ‘amenity space’ is in itself subjective. The Guidance Note provides additional guidance to its members on defining what is amenity space. However, what a surveyor may deem as an impact or not on your free enjoyment of the property may differ greatly from your assessment, so we would advise caution and investigate further with a specialist remediation contractor.
As referred to previously the other subjective consideration on amenity use impact is the restricted use implications from the plant’s underground rhizome zone. A property surveyor is not required to take the likely underground rhizome presence into consideration when assessing the impact on amenity use. Whereas specialist remediators would, setting out the implications for the property owner/occupier in disturbing the rhizome zone, making clear the extended property use restriction that it can have for them.
What about The Law Society ‘Property Information Form’?
The TA6 Property Information form legally needs to be completed by the property seller (vendor) and includes a question on Japanese knotweed.
The vendor is asked in the TA6 form if they are aware of Japanese knotweed affecting the property? The vendor is advised that the property is affected if knotweed is present within the boundaries of the property (even following control works by a specialist remediation contractor), or present off-site within 3m of the boundary of the subject property.
The vendor can answer ‘don’t know’ and in those cases, caveat emptor applies, and the buyer should conduct their own investigations into knotweed impact if they so wish to do so.
The release of the new RICS Guidance Note may promote the RICS and The Law Society to review the TA6 wording and ensure there is appropriate correlation in the guidance and assessment both documents give. More to come on this maybe.
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’s knotweed may have on a property (i.e. 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 ourselves) when looking to sell or buy and property impacted by Japanese knotweed.
Jennifer Holmes, Head of Marketing & Business Development, Japanese Knotweed Ltd