Japanese knotweed
What should you ask if Japanese knotweed appears to be growing through a patio or a path?
Ask where the canes are, and do not treat the hard surface as a barrier. GOV.UK says you must not cause Japanese knotweed to spread, and that soil and plant material are not ordinary waste. A patio can hide the crown and still have growth in the joints. A home survey does not excavate and does not assign a price. The 2022 RICS categories are for a proper assessment, not for a photograph of a crack in a slab.
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?
The RICS journal’s account of the 2022 standard looks at visible material damage and at amenity, and it expects a specialist when the plant is identified. A cane in a joint is visible growth. It is not a measurement of the rhizome under the slab. Breaking the patio to “have a look” can spread the plant if the material is then moved as ordinary rubble. That is the opposite of the GOV.UK duty.
A management plan, if one exists, should say what happens when the surface is disturbed. The surveyor will not reconstruct a missing plan. There is no RICS figure for lifting a patio or for treatment. Ask a specialist who will name the plant before you deduct a new garden from the price.
What should you ask your surveyor?
- Did you identify knotweed, or only growth in the joints?
- How far does the visible growth extend?
- Are you giving a management category, or saying a specialist should?
What are the typical next steps?
- Do not break out the patio before exchange.
- Do not put the cuttings or the broken slab in the green waste.
- Ask the seller for any management plan and give it to a specialist with the survey note.
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
Is bamboo in a patio the same category?
No. Bamboo is not a Japanese knotweed category. Name the plant. Do not file one as the other.
Does a new patio mean the knotweed has gone?
No. A new surface can hide it. Growth in the joints is a reason to ask, not a completion certificate.