RICS Japanese Knotweed Guidance

What Is the RICS Knotweed Guidance?

The Royal Institution of Chartered Surveyors (RICS) provides formal guidance to surveyors on how to identify, assess and report Japanese Knotweed during property inspections. The most recent update (2022) replaced the old “7‑metre rule” with a more evidence‑based, risk‑focused approach.

• Focus on actual impact — not just distance from the property.
• Clearer categories — surveyors classify Knotweed based on visibility and effect.
• More balanced assessments — reducing unnecessary down‑valuations.

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The Old System: The 7‑Metre Rule

Before 2022, surveyors followed a simple rule: if Knotweed was within 7 metres of a building, it was automatically considered a risk. This often led to:

• Over‑cautious valuations
• Mortgage delays
• Unnecessary alarm for homeowners

RICS replaced this rule because it did not reflect real‑world evidence.

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The New System: Risk‑Based Assessment

The updated guidance uses a more practical, evidence‑driven approach. Surveyors now consider:

• Visibility — is Knotweed present and identifiable?
• Location — is it on the property, neighbouring land, or both?
• Impact — is it affecting structures, drains, or amenity space?
• Management — is a professional plan already in place?

This allows surveyors to distinguish between low‑risk and high‑risk situations.

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The Four RICS Categories

Surveyors now classify Japanese Knotweed into four categories:

• Category A — Knotweed causing clear structural damage or significant impact.
• Category B — Knotweed present and unmanaged, but not yet causing damage.
• Category C — Knotweed present but under a professional management plan.
• Category D — Knotweed visible on neighbouring land but not on the property.

Each category guides lenders on whether a mortgage can proceed and what documentation is required.

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How RICS Guidance Affects Mortgage Applications

Most lenders now follow the RICS categories when deciding whether to approve a mortgage. In general:

• Category A or B — lenders usually require a PCA‑accredited management plan.
• Category C — mortgages typically proceed with evidence of ongoing treatment.
• Category D — often no action required unless the Knotweed is likely to spread.

This system reduces unnecessary refusals and gives lenders clearer, more consistent information.

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What Homeowners Should Do

If a surveyor identifies Japanese Knotweed under the RICS guidance, the best next steps are:

• Get a PCA‑accredited survey
• Begin a professional treatment plan
• Keep documentation for lenders and future buyers
• Monitor the site annually

Professional management ensures compliance with lender expectations and protects property value.

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What Buyers Should Know

If you’re buying a property where Knotweed has been identified:

• Request the RICS category from the surveyor
• Check whether a management plan is in place
• Ensure the guarantee is transferable
• Confirm the lender accepts the documentation

With the correct paperwork, most purchases proceed without issue.

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Need Help Interpreting RICS Guidance?

If a surveyor has raised concerns about Japanese Knotweed, we can provide a PCA‑accredited survey and a lender‑approved management plan.