Japanese knotweed
What is RICS management category C for Japanese knotweed?
Category C is “Manage”. The RICS journal describes knotweed that is present but not causing damage and not affecting amenity. The impact is lower. The journal still says a remediation specialist should be recommended in all cases. It also said lenders were not expected to retain funds for this category. Confirm that with your own lender.
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?
Category C is not “ignore it”. Government guidance still requires you not to let Japanese knotweed spread off the property. A small clump at the end of a large garden can be C if the surveyor believes it does not restrict the use of the space and has not damaged a structure. Another surveyor might see it differently. The category is a professional judgement, which is why the letter matters.
Ask the seller whether they already have a management plan. If they do, read who it binds and whether it transfers. If they do not, a specialist can still advise you of the options, including management rather than an immediate excavation. Excavation is not the automatic response to category C. Ask the specialist to say so in writing if that is their view.
What should you ask your surveyor?
- Where is the growth, and what use of the garden does it leave unaffected?
- Are you using category C, or only noting a plant you think might be knotweed?
- What specialist advice do you still expect, given the “all cases” recommendation in the RICS journal?
What are the typical next steps?
- Do not dig it out at a weekend. That can spread it and can breach the rules on disposal.
- Ask a specialist whether management is proportionate. Keep their answer.
- Tell the lender the category rather than the word “knotweed” alone.
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
Does category C mean the plant is dead?
No. It means the impact on the day was limited. Dormant-looking winter stems can grow again.
If the seller has mown the clump, is it still category C?
Mowing does not decide the category and can make identification harder. Ask the surveyor what they could actually identify.