RICS Draft Guidance Note: Japanese knotweed and residential property, 1st edition

3 Property inspection and Japanese knotweed

3.1 Valuation or survey?

RICS members understand that property inspections may be carried out to provide a valuation (i.e. an opinion of market value), a survey (i.e. an appraisal of a property's structure) or a combination of the two. The depth of inspection varies significantly depending on the specific requirements but unfortunately this important distinction is not always understood by the public, especially when basic pre-purchase valuations carried out for lending purposes are misinterpreted by purchasers as being more detailed surveys.

A valuation inspection is focused on identifying the key attributes and factors that affect the value of the subject property. It is necessarily much more superficial than a survey, which involves an assessment of the physical structure of a property and factors which may affect its condition.

The introduction of the RICS Home Survey Standard, 1st edition, in March 2021, aimed to clarify the difference between different levels of survey and ensure that private clients are fully informed about the options available.

It is important to recognise that standard residential valuations and surveys are not specifically focused on finding and advising on Japanese knotweed any more than they are intended to provide formal risk assessments. However, a valuer or surveyor understands that if a significant personal risk issue, such as a defective balcony railing, becomes apparent during the normal course of an inspection it needs to be reported to the client. In the same way, RICS members must be mindful that Japanese knotweed may be encountered during any inspection. When this happens the valuer or surveyor should be capable of providing guidance to the client that is appropriate to the level of inspection.

RICS members should be aware that standard clauses in Terms and Conditions of Engagement attempting to exclude any liability associated with the presence of Japanese knotweed are unlikely to meet the requirements of the Unfair Contract Terms Act 2015 or to withstand scrutiny of the courts.

3.2 Mortgage valuations

The requirements for most physical mortgage valuation inspections are specified at UK VPGA 11 in the RICS Valuation - Global Standards: UK national supplement.

UK VPGA 11.3 states:

'1. The visual inspection to be undertaken in the present context covers as much of the exterior and interior of the property as is readily accessible without undue difficulty or risk to personal safety. Although personal judgement has to be used, this inspection should include all of the property that is visible when standing at ground level within the boundaries of the site and adjacent public/communal areas, and when standing at the various floor levels.

'2(c) The inspection includes garaging, car parking, other outbuildings (excluding leisure complexes) of permanent construction and any other structures attached to the dwelling. If relevant, their impact on the value of the property is to be noted.

'2(e) The land within the ownership should be inspected as far as is practicably possible, and any material matters recorded and reported.

'2(f) Where there are locational factors that may impact value, they should be recorded and reported, with some comment where appropriate. Certain problems, such as flooding, mining settlement, subsidence, woodworm, invasive vegetation, radon gas, mundic and other issues are particularly prevalent in certain districts. If appropriate, the valuer should make some reference to these defects, even if the subject property does not appear to be affected at the time of the inspection.'

3.3 Surveys for pre-purchase advice and other purposes

The RICS Home Survey Standard makes it mandatory for surveys, typically pre-purchase surveys, to be benchmarked against three defined inspection and reporting levels. Levels one and two are described as offering professional reports at an economic price. A level three survey is typically the most thorough and detailed type of pre-purchase survey offered by RICS members.

Individual services offered by surveyors may vary from the defined levels but surveyors' Terms and Conditions of Engagement are required to specify what these variations are in relation to the benchmarked levels. The standard requires surveyors to make their clients aware of the differences in inspection and reporting between the different levels. The depth and amount of detail required for any given survey and report will, therefore, depend on the Terms and Conditions of Engagement agreed with the client.

If an RICS member has the skill, knowledge and training to include the additional service of identifying and advising on Japanese knotweed as part of a pre-purchase survey then they can offer that, providing it is covered in their Terms and Conditions of Engagement and it is discussed and agreed with the client.

For most RICS members, however, if a client specifically requires advice on whether or not Japanese knotweed is present at a property, or advice on remediation, they should recommend the client to commission an inspection or advice from a specialist remediation company that is a member of a recognised trade body.

3.4 Knowledge of the area and pre-inspection checks

The surveyor should be familiar with the type of property to be inspected and the area where it is situated but there is also a requirement to undertake appropriate pre-inspection research. The depth of desktop research will depend on the level of service but should include information about the general environment, neighbourhood and the subject property.

Surveyors are advised to ensure that they utilise publicly-available resources. Online distribution map resources may give some rough indication of the local frequency of Japanese knotweed in an area. In some regions, local authorities may provide useful information, especially where Japanese knotweed infestations are common. Some online street and aerial imagery incorporates timelines with earlier images of the same location. Street imagery can be especially helpful at showing the subject property and surroundings, including visible Japanese knotweed, in previous years and in different seasons.

Neighbourhood features associated with the growth of Japanese knotweed typically include the presence of:

  • local water sources, such as culverts, ponds, canals and lakes
  • public and private paths, cycle-paths, roads, railway or underground railway embankments, dual carriageways and motorways
  • large open spaces, car parks and derelict and cleared sites and
  • commercial and industrial buildings, workshops, storage depots and similar.

Likely locations for Japanese knotweed growth can be identified prior to and after the actual inspection, for example, while driving through the neighbourhood, arriving at or leaving the property, parking, and preparing for the inspection.

3.5 Information from the vendor

It is important that, where relevant and practical, the owner and/or seller or their agent should be asked whether the property or any neighbouring properties have been affected by Japanese knotweed and, if applicable, for details of any Japanese Knotweed Management Plan or guarantees/warranties. Ideally this should be done at the start of the assessment process so any information obtained can be followed up during the inspection. The client should also be advised to ask their legal adviser to specifically enquire about any Japanese Knotweed Management Plan and any associated warranty/guarantee.

3.6 The inspection of the property

The requirements for inspecting the grounds vary between the survey levels and Appendix B of the RICS Home Survey Standard illustrates differences between the inspection levels. It states that at all survey levels 'the RICS member will carry out a visual inspection of the grounds from within the boundaries of the subject property and, where necessary, from adjoining public property.' The Appendix does not provide a comprehensive listing of what is or is not inspected but provides 'critical benchmarks around which an RICS member's service can be built.'

The Appendix describes the benchmark for a level one survey as 'a cursory inspection of the grounds during a general walk around.' For a level two survey the benchmark is 'a thorough inspection of the grounds, noting any limitations.' At level three, the benchmark states that:

'As in level two, the RICS member should perform a comprehensive inspection of the grounds, noting any limitations. Specific defective features and other matters associated with the grounds can be costly to resolve and may affect the client's decision. Consequently, the RICS member should fully account for these during a level three service and be prepared to follow the trail of suspected problems to a greater extent than at levels one and two. Examples include assessing retaining walls in danger of collapsing, deeply sunken paths or driveways, and dilapidated boundary walls or fences, as well as the legal and insurance implications.'

The descriptors 'cursory', 'thorough' and 'comprehensive', especially the last two, must be understood in the context of a survey inspection of a whole property, of which the grounds are only one element. They must not be interpreted as requiring a plant by plant check for Japanese knotweed. The potential difficulties faced by surveyors and valuers at properties with larger plots, where planting is dense, those with boundaries that are difficult to see or access for some reason and those defined by hedges or high fences are fully recognised, not to mention practical constraints imposed by the seasons and the weather conditions on the day of the inspection.

The inspection should include consideration of adjoining properties where reasonably possible, especially along the boundaries, when standing at ground level within the boundaries of the site, when standing at the various floor levels within the property and from adjacent public/communal areas. If views are unduly restricted this should be noted.

The measure of adequacy of any individual inspection remains the long-established one of 'reasonableness', which is largely determined by the particular circumstances facing the surveyor on the day of the inspection. Experience has shown that detailed site notes supported by photographs frequently assist in demonstrating the situation at the time of an inspection and any limitations imposed on its scope.

If Japanese knotweed is clearly visible on site during the normal course of an inspection it is reasonable to expect, all other things being equal, that it should be identified by a valuer or surveyor and reported to the client, along with appropriate recommendations. It is worth repeating, however, that valuations and pre-purchase surveys by RICS members should not be regarded as equivalent to, or substitutes for, an inspection by a specialist remediation company.

3.7 Identification of Japanese knotweed

The RICS information paper published in 2012 included some basic information and photographs to aid the identification of Japanese knotweed. There is now a wealth of information available to assist learning and there is an expectation, not least by the courts, that residential valuers and surveyors should have a working knowledge of what Japanese knotweed commonly looks like during all seasons of the year (see Hardwicke (2019): Oh, that Knotweed! Sorry, didn't I mention it?). There has also been an immeasurable increase in online resources and readily accessible imagery for those seeking further information. Primary sources to consult include online search engine image databases and the websites of remediation companies.

It is recommended that smartphone apps can be utilised to assist with the identification of plants about which there is doubt. Alternatively, many specialist remediation companies provide online identification services with a fast turnaround.

Those seeking further information about Japanese knotweed, including its identification, should consult the current edition of the document published by the Property Care Association, Guidance for Professional Valuers and Surveyors, which also contains information about alternative methods of remediation. It is anticipated that this publication will be periodically updated in the light of the latest research.

3.8 Site records

When Japanese knotweed is encountered during an inspection the valuer or surveyor is recommended to note its location on a site plan and record details such as:

  • proximity to built structures, hard-landscaped areas, possible lines of drain runs and any damage or disruption noted
  • the location, height and area of all 'stands' of Japanese knotweed
  • whether stands are on or off site, or crossing boundaries
  • any evidence (verbal, documentary or visual) of current or previous management and
  • photographic records should be taken for later reference even if they are not required for inclusion in reports.

The visible extent of an infestation may not accurately indicate the full magnitude of the area affected and concealed growth below ground level may be much more extensive. The original growth may have been cut back or partially treated. In some cases, there may have been attempts at concealment. Nevertheless, a description of the visible infestation is a useful record. Surveyors and valuers are familiar with estimating areas so, as an aid to consistency, it is suggested that the following descriptive scale is adopted:

Individual stands can be described in terms of their size:

  • Very small: 1m2 or less
  • Small: 1m2 to 4m2 [e.g. 2m x 2m]
  • Medium: 4m2 to 25m2 [e.g. 5m x 5m]
  • Large: 25m2 to 100m2 [e.g. 10m x 10m]
  • Extensive: greater than 100m2

Using this method, one property might have 'several small stands in scattered locations' while at another there might be 'an extensive infestation on adjoining land'. It is worth repeating that, while the visible growth may be helpful for a preliminary assessment, it cannot be assumed to provide a definitive guide as to the full extent of an infestation or the likely cost of remediation.