TL;DR - RICS Knotweed Guidelines (At a Glance)
The Royal Institution of Chartered Surveyors (RICS) Japanese knotweed guidelines provide an evidence-based framework for assessing risk in residential property. Japanese knotweed does not automatically cause damage or prevent mortgage lending.
Under current RICS guidance:
- Risk is assessed based on impact and interaction, not distance alone
- The historic 7-metre rule no longer applies automatically
- Presence alone does not require removal or mortgage refusal
Surveyors focus on:
- Visible material damage to structures
- Impact on amenity or habitable space
- Location relative to property boundaries
The Royal Institution of Chartered Surveyors (RICS) provides guidance to surveyors on assessing Japanese knotweed in residential properties. The RICS Guidance Note on Japanese knotweed became effective on 23rd March 2022, introducing four management categories (A to D) instead of the previous risk categories (1 to 4).
The current RICS framework emphasises a 3-metre distance for assessing off-site infestations rather than the abolished 7-metre rule.
Overall, RICS guidance supports proportionate, evidence-led decision-making, allowing property transactions to proceed where risk is properly assessed and managed.
Table of Contents
Introduction to Japanese Knotweed and Residential Property
This guide is intended for homeowners, property buyers, and professionals seeking to understand the impact of RICS Japanese Knotweed guidance on residential property. Japanese Knotweed (Reynoutria japonica) is a highly invasive plant introduced to the UK in the 19th century.
The RICS Japanese Knotweed Guidelines, created by the Royal Institution of Chartered Surveyors (RICS), are fundamental to how Japanese Knotweed is identified, documented, and controlled throughout the UK Residential Property Market. It is the RICS Members and Chartered Surveyors who apply the RICS Japanese Knotweed Guidelines to identify the extent of an infestation, advise on the management and control of the invasive species and guide all parties involved through the remedial work and risk assessments.
Understanding these guidelines is crucial for anyone involved in property transactions, as Japanese Knotweed can affect property value, mortgage eligibility, and legal responsibilities.
The RICS Japanese Knotweed Guidelines are developed using evidence-based practice and with significant input from the House of Commons Science and Technology Committee, which has placed emphasis on the use of common sense and scientific consensus when creating reasonable, research driven standards.
Japanese Knotweed remains a relevant factor to be taken into consideration in residential property transactions; its uncontrolled growth may ultimately have a potential adverse effect upon buildings, amenity space and long-term mortgage finance, rather than necessarily causing damage itself.
Understanding how RICS Guidance is utilised can make a substantial difference to property owners when attempting to progress a sale, remortgage or secure mortgage finance if delayed.
Understanding Japanese Knotweed and Residential Property Risk
Japanese Knotweed can impact Residential Property in several ways, depending on location, extent and interaction with structures; RICS Guidance clearly states that the risk will need to be assessed holistically, rather than simply based on proximity alone.
Key Risk Factors
- causing Visible Material Damage;
- restricting Access to Amenity Space (e.g., gardens, etc.);
- affecting Habitable Space;
- present Within or Close to the Property Boundary;
- likely to encroach into the Property from Neighbouring Land or Adjoining Land;
Features of Significant Value (e.g., Habitable Spaces/Garage, etc.) are also taken into consideration when assessing the risk of Japanese Knotweed. The New Guidance clearly States that the Distance of Japanese Knotweed to Habitable Space will NOT affect the Management Categories of the Knotweed.
Therefore, the risk presented by Japanese Knotweed is Contextual, so the presence alone of Japanese Knotweed does not necessarily mean it is causing Material Damage, and each Case needs to have an Informed Assessment.
RICS Guidance Note for Property Owners
The RICS Guidance Note offers clear guidelines to property owners who may have residential property affected by Knotweed and need guidance on identification, classification and management of Japanese Knotweed, which is based upon the current scientific evidence, lender requirements and industry best practices.
The RICS Guidance Note is primarily intended for Residential Property Practitioners (Registered Surveyors and Valuers) and will provide these professionals with the recommended actions when they are conducting residential property surveys.
Surveyor Assessment Process
- A reliance on evidence-based assessment instead of assumptions
- Risk categories are clearly defined
- Proportionate risk management, not blanket removal
- Where appropriate, the use of specialist remediation
Japanese knotweed management categories were developed to help reduce unnecessary disruption for property owners while meeting lender and surveyor expectations, and to help clarify the significance of Japanese Knotweed and the necessary actions for all parties involved in a property.
Do RICS Surveyors Check for Japanese Knotweed?
Yes, RICS Surveyors have an obligation to identifyJapanese Knotweed during their inspection of a residential property where there is visible evidence of the plant or when it is reasonably likely that there may be growth at the property.
Although a property surveyor would not carry out excavation or investigation in the soil, they would assess the presence of visible growth, how close it is to structural elements, its effect upon the amenity of the property and its proximity to the subject property boundary. If Knotweed is found, the surveyor will usually recommend that a specialist report be carried out by a specialist Remediation Contractor.
Identifying Japanese Knotweed Under RICS Guidance
To correctly identify Japanese Knotweed, surveyors use visual characteristics (i.e., bamboo-like hollow stem; leaf type – large, shield-like), and the overall density of growth as it grows in each season. The best way to get the most current identification and assessments is by going to the RICS website for their current guidance note(s) and/or updates.
But don’t let the visible growth fool you. RICS Guidance has acknowledged that the rhizome area can extend past the visible growth boundaries, especially when the adjacent property or properties have off-site Knotweed. This is due to Japanese Knotweed’s extensive underground root system, known as rhizomes. Therefore, a comprehensive or “holistic” assessment is typically needed to evaluate the full degree of risk.
Japanese Knotweed is classified as controlled waste under the Environmental Protection Act (1990), which has implications for its removal and disposal. Japanese Knotweed spreads via an extensive underground root system called rhizomes.
Once Japanese Knotweed has been identified, the next step is to determine the appropriate management category under RICS guidance.
Visual Identification Features
We know this can be a little bit complicated to understand, so we have created an easy to use RICS assessment helper. Simply answer the questions below to find out what management category you are:
RICS Assessment Helper
A quick, evidence-led decision guide based on the on-site / off-site assessment pathway you provided. This supports understanding only and does not replace a survey or specialist report.
This tool provides general guidance only, based on the decision pathway shown in the RICS on-site/off-site assessment flowchart you supplied. It is not official RICS advice and does not constitute a valuation, survey, or lending recommendation. For transactions and mortgage finance, a specialist report may be required.
Where was Japanese knotweed seen?
Choose the option that best matches what was observed during inspection.
Is it actually causing visible material damage to a structure?
For example: clear impact to walls, hardstanding, drains, outbuildings, or other built elements.
Is it likely to prevent use or restrict access to amenity space?
Amenity space is typically usable garden/yard/patio areas that support normal enjoyment of the property.
Is it visible on adjoining land within 3 metres of the boundary?
This is an off-site screening question based on the pathway in the flowchart.
Your likely outcome
Based on the answers selected in this tool.
Next step (if you need certainty)
If this relates to a sale, purchase, or mortgage finance, the safest route is a site visit and a written specialist report with a suitable remedial plan. That is what lenders and chartered surveyors typically rely on for proportionate, evidence-led decisions.
Management Categories for Japanese Knotweed
A key element of the RICS guidance is the introduction of new management categories, replacing the historic one-size-fits-all approach.
The new assessment process introduces four management categories (A to D), which replace the previous risk categories (1 to 4). The main differences between the old and new systems are the updated evaluation criteria and the way knotweed risk is categorised for property and lending decisions.
These management categories allow surveyors and lenders to distinguish between low-risk and higher-risk scenarios, improving consistency across the residential property market and reducing unnecessary mortgage refusals.
| Management Category | Primary Criteria | Typical Risk Profile | Required / Recommended Action |
|---|---|---|---|
| Category A – Action | Visible material damage to a structure. | High – direct interaction with the built environment. | Specialist remediation required. Specialist report typically required. Mortgage retention commonly applied (lender dependent). |
| Category B – Action | Amenity space restricted or likely to be restricted. | Medium to high – impact on use and enjoyment. | Specialist remediation advice recommended. Specialist report typically required. Mortgage retention may be applied. |
| Category C – Manage | No visible material damage or amenity restriction. | Low – manageable under current guidance. | Ongoing management and monitoring recommended. Mortgage retention not typically required. |
| Category D – Report | Off-site presence with limited current impact. | Very low – contextual awareness only. | Record presence and location. No action normally required unless future risk is identified. |
Management Category A – Action Required
Management category A applies where Japanese Knotweed is actually causing visible material damage to a structure. This represents the highest level of impact within the RICS management framework.
Examples may include:
- Damage to walls, foundations, or outbuildings
- Distortion or failure of hardstanding, paths, or retaining structures
- Clear interaction between knotweed growth and the built environment
Where management category A is identified, RICS guidance is clear that immediate action is required. A specialist remediation contractor should be instructed to assess the extent of the damage and advise on appropriate action.
In these cases:
- A specialist report is required
- A suitable remedial plan must be put in place
- Mortgage retention is commonly recommended by lenders pending specialist advice
This category reflects situations where Japanese Knotweed has moved beyond risk and is actively affecting the property.
Management Category B Explained
Management category B applies where Japanese Knotweed is present but not causing visible material damage and does not materially restrict access to amenity space or habitable space.
In these cases:
- A specialist report is usually required
- A suitable remedial plan may involve long-term management
- Mortgage finance is often available, subject to confirmation of appropriate management
This category reflects a balanced, evidence-led assessment of risk.
Management Category C and Its Implications
Management category C applies where Japanese Knotweed is causing visible material damage, materially restricting amenity space, or presenting a clear risk to structures.
Under management category C:
- Specialist remediation advice is required
- A detailed specialist report must support advising lenders
- Mortgage retention may apply until appropriate management is implemented
Importantly, this does not automatically prevent lending. It requires clear evidence of specialist remediation and ongoing management.
Management Category D – Report (Off-Site Presence)
Management category D applies where Japanese Knotweed is present off site, typically on neighbouring or adjoining land, and is considered to have limited current impact on the subject property.
This category is most commonly used where:
- Knotweed is visible on neighbouring land
- Growth is within proximity to the property boundary
- There is no current restriction on amenity space or habitable space
Under management category D:
- The presence and location of Knotweed should be recorded and reported.
- No action and no mortgage retention are typically required for lending purposes.
- Exceptionally, if the scale of the off-site infestation may affect future value or saleability, further reporting may be appropriate.
This category allows surveyors to acknowledge off-site Knotweed without overstating risk, aligning with modern RICS guidance and current lender expectations.
What the 7-Metre Rule Actually Means Under Current Guidance
The historic 7-metre rule is no longer applied as a blunt instrument under current RICS guidance. Distance alone is not a reliable indicator of risk.
Instead, surveyors assess interaction, impact, and likelihood of damage. Japanese Knotweed within 7 metres of a property boundary does not automatically prevent mortgage lending.
For a detailed explanation, see our dedicated guide on what the 7-metre rule actually means under current guidance.
Impact on Mortgages, Lending and Mortgage Retention
Mortgage lenders rely on RICS guidance to inform property lending advice. Where Japanese Knotweed is identified, lenders typically look for:
- Clear risk categorisation
- A specialist report from a specialist remediation contractor
- Evidence of a suitable remedial plan
Mortgage retention is applied selectively, usually where risk remains unmanaged or unclear. Clear documentation and appropriate management are often sufficient to satisfy lender requirements.
Off-Site Knotweed, Neighbouring Land and Boundaries
RICS guidance explicitly addresses off site knotweed and possible encroachment from neighbouring land. Knotweed does not need to be within the property boundary to be relevant.
Surveyors consider distance, visible growth, access to amenity space, and the likelihood of future encroachment when assessing risk.
When Specialist Remediation Is Required
Specialist remediation is required where Japanese Knotweed presents a material risk to residential property or mortgage finance. This work should be undertaken by a specialist remediation contractor experienced in residential scenarios and lender requirements.
Specialist remediation may include herbicide treatment programmes, monitoring, and formal management plans. Excavation is not always required and is not the default position under RICS guidance.
Appropriate Action for Property Owners
For property owners, appropriate action depends on risk category, location, and lender expectations.
Best practice includes:
- Commissioning a specialist report
- Following the RICS guidance note recommendations
- Implementing appropriate management early
- Retaining clear documentation for surveyors and lenders
Early, evidence-based action often prevents delays within the residential property market.
Summary for Mortgage Lenders and Valuers
Japanese Knotweed is assessed using the same methods as are currently recommended by RICS for assessing the risk associated with Japanese Knotweed in residential properties. The method of assessing the risk is based upon an evidence led inspection to determine the Category of Management of the infestation; Specialist reports will be prepared as necessary.
The presence of Japanese Knotweed does not mean that there is ‘material damage’ to the residential property. It therefore does not prevent a lender from providing finance to purchase the property. Mortgage lending decisions are made based on physical interaction with the structures affected by Japanese Knotweed, whether the infestation has impacted the amenity value/habitable area of the residential property and whether an appropriate management plan exists which is being implemented by a specialist remediation contractor.
Final Thoughts on RICS Japanese Knotweed Guidelines
RICS guidelines for Japanese Knotweed have brought clarity to what was previously a murky area of concern. While the presence of Japanese Knotweed is still considered a significant issue, it can be effectively managed when the right approaches are taken.
For both the residential property owner, the surveyor and the lender, the focus is now placed on making decisions based on proportionality, evidence, and the support of specialists in remediation rather than fear or assumptions.
FAQ
Do RICS surveyors check for Japanese Knotweed?
Yes. Surveyors acting under the auspices of RICS (Royal Institution of Chartered Surveyors) should be able to identify visible Japanese Knotweed when it is present and/or reasonably believed to be present at an inspected property. While surveyors would not expect to find evidence of underground rhizomes and therefore would not expect to excavate them, they would still look for visible signs of growth, and how that growth relates to the surrounding property and any other factors that might influence their assessment of the situation.
If Japanese Knotweed is identified by the surveyor, they typically recommend a Specialist Report from a Remediation Contractor who can provide an accurate Risk Assessment and recommendations as to how to proceed with managing the Knotweed.
How do RICS surveyors identify Japanese Knotweed?
Surveyors assess Japanese Knotweed primarily based upon visible characteristics, including:
- Growth pattern
- Stem structure
- Leaf shape
- Seasonal indicators
The visible extent of the Knotweed's growth is also considered in terms of its relationship to buildings, boundaries, amenity spaces, and neighbouring land. Although visible growth does not necessarily indicate the extent of the Rhizome Zone, if a surveyor believes that Japanese Knotweed is present and/or reasonably suspected to be present, they will typically recommend a Specialist Assessment.
Do you legally have to remove Japanese Knotweed?
While there is no automatic legal obligation to eradicate Japanese Knotweed due to its presence on a property, Property Owners have obligations to control the spread of Japanese Knotweed and to take steps to mitigate any risks associated with Japanese Knotweed, where those risks relate to neighbouring land, structures, or the broader environment.
Lenders to Buyers/Sellers, in connection with property purchases, will frequently request proof of adequate management of Japanese Knotweed rather than eradication.
