Category A: action needed, structural damage
Knotweed is present and causing visible material damage to a significant structure. This is the category most likely to affect value and hold up a mortgage, because there is a real repair cost attached (source: ww3.rics.org).
Category B: action needed, no structural damage
The knotweed is not damaging the structure, but it is likely to prevent use of, or restrict access to, part of the garden or amenity space. The value impact here is usually about remediation cost, not structural repair (source: ww3.rics.org).
Category C: manage, no action required
Knotweed is present but is not causing damage and is not affecting use of the garden. RICS guidance expects minimal impact on value in this category (source: ww3.rics.org).
Category D: report only, and this is the one that still uses distance
This applies when knotweed is growing within 3 metres beyond the boundary, on land you don't control, so there's nothing to manage on your own property. That 3-metre figure is the one part of the old rule RICS kept, just shrunk from 7 metres (source: ww3.rics.org).
What this means for a lender
RICS guidance sets the category; it doesn't set lending policy, and individual lenders decide their own response to it. As a general pattern, categories A and B are the ones most likely to prompt a lender to ask questions before releasing funds; category C is the one least likely to. Treat this as what to expect, not a promise of what any specific lender will do.
If your survey has flagged knotweed in category A or B, see our guide to getting a management plan and insurance-backed guarantee from a PCA specialist.
Who to see first
If a surveyor has flagged knotweed on or near a property you are buying, selling or remortgaging, start with a RICS surveyor to explain what the finding means for the lender, and a Property Care Association specialist for a treatment plan. Both bodies publish a find-a-professional tool.
What to check before you agree any work: the survey's own wording and category; whether there is a written management plan; and, if a guarantee is offered, what it covers and for how long.
VettedHome does not vet or recommend surveyors or contractors.
Questions people ask
Does knotweed within 7 metres of my house automatically block a mortgage?
No, not any more, for three of the four categories. RICS dropped the blanket 7-metre rule in March 2022. What decides A, B and C is whether the knotweed is actually causing damage or restricting use. Only category D still uses a distance test, and that one is now 3 metres.
What should I ask my surveyor?
Ask which of the four RICS categories, A, B, C or D, they have assigned, and why. That category is what actually matters to a lender, not the bare fact that knotweed is present somewhere on or near the property.
What if my survey report still talks about a 7 metre distance?
That reflects the pre-2022 approach and is out of date for categories A, B and C. The only distance still in current RICS guidance is the 3-metre test for category D.
Sourced from RICS Property Journal: Japanese knotweed, new guidance comes into effect. See our data sources and updates page.
Editor, VettedHome
Adam leads VettedHome's editorial coverage of UK home services. He is the founder and managing director of Muswell Rose, the commercial strategy and modern systems business behind a portfolio of UK information sites, and he researches and writes the plain-English guides that help homeowners choose between installers and trades, drawing on the standards set by the relevant bodies for each job, such as Gas Safe Register, NICEIC, MCS, TrustMark and the Property Care Association. He is clear about what to check before any work starts.
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