Japanese knotweed
What is RICS management category B for Japanese knotweed?
Category B is also headed “Action”. The RICS journal describes it as knotweed on the property that is not causing material damage to a structure, but is likely to prevent use of, or restrict access to, amenity space. Specialist advice is still recommended. Any effect on lending is a question for the lender, not a figure in the survey.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Amenity space means the garden you can actually use. A stand that blocks a path, a lawn or a patio can be category B even though the walls are unmarked. The journal said most lenders were expected to want a specialist report and might retain funds on A or B. That was an expectation in 2022. Ask your lender what they do now, and give them the category the surveyor actually used.
A management plan and an insurance-backed guarantee are what specialists often offer. The home survey does not write that plan. Government guidance on preventing spread still applies: do not cut it down and take the waste to the tip. Ask the specialist how waste will be handled. Do not invent a removal cost from the area of the stand.
What should you ask your surveyor?
- Is the growth restricting the garden, or is it a small clump you could walk around?
- Did you see damage to a shed, a path or a wall, or only the plants?
- Which category, if any, are you assigning?
What are the typical next steps?
- Get a remediation quote that describes the area and the plan, not a one-line “removal”.
- Ask the lender whether category B changes the offer. Do it with the report in your hand.
- Do not treat a tidy winter garden as proof the rhizome has gone. The surveyor saw one day.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
Can category B become category A later?
If the plant later damages a structure, the impact has changed. A category is an assessment on the day, not a forecast you can cash.
Is a shed a significant structure?
The journal’s category A talks about a significant structure. Ask the surveyor what they treated as significant. Do not promote a timber shed to a house wall on your own.