Japanese knotweed
What should you ask if Japanese knotweed is on neighbouring land, clearly more than three metres from this boundary?
Ask the surveyor to say it was off site and beyond the distance they could judge, and do not invent a category. The 2022 RICS approach, as the journal describes it, uses three metres rather than the old seven for off-site growth that is reported. Plants further away are not that near-boundary category. They are also not a reason to ignore knotweed on this plot. A home survey does not cross the boundary to measure.
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?
Distance by eye from a garden is approximate. If the surveyor could not pace it, they should say so. Category language belongs to an assessment that has identified the plant and applied the standard. A buyer who writes “category D” onto a clump two gardens away is misusing the document. GOV.UK’s duty not to cause spread still applies to anything on the land you will own. It does not make you the neighbour’s contractor.
Your solicitor can ask what the seller knows. You cannot lawfully march next door and spray. Lenders ask their own questions. There is no RICS price for a neighbour’s stand of knotweed. Do not deduct a treatment figure for a plant you do not control and the survey has not categorised.
What should you ask your surveyor?
- Did you see knotweed on this plot, or only beyond the fence?
- Are you estimating a distance, or did you measure?
- Are you applying a management category? If not, please do not imply one.
What are the typical next steps?
- Keep on-site and off-site notes apart.
- Do not enter the neighbour’s garden.
- Ask your solicitor what to enquire. Do not instruct a spray on land you do not own.
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
If it is within three metres, is that automatically damage?
No. The journal’s account separates damage, amenity and off-site reporting. Distance is not a crack.
Does the three-metre point apply in Scotland?
The RICS standard is the professional document. The survey should still say what was seen. Do not assume a category code was used if the report does not use one.