The survey says knotweed is at the rear boundary but not which side of the fence the crowns are on. What should you ask?

What is the fuller explanation?

A home survey describes the property being bought, from the land the surveyor was entitled to walk. Looking over a fence is not inspecting next door, and it is not measuring a root. RICS management categories are a structured judgement about impact, not a sticker you add because canes touch a panel. If the growth is clearly in this garden, the report can say so. If it is clearly beyond the fence, the report can say it was seen off the plot and that the boundary was not crossed. If the crown is in the line of the fence and the base is hidden, the honest word is that the side was not established.

Your solicitor asks the seller what they know and what the neighbour has said. The survey does not write to the neighbour and does not decide ownership of the fence. Government guidance on not causing spread still applies to anything growing on land you will control, which is why guessing is a poor basis for cutting it. Do not cut the boundary growth back to get a clearer photograph. If a lender asks whether knotweed is on the property, the accurate reply is the surveyor’s limit: seen at the rear boundary, side not established. A specialist who is allowed to look properly can resolve what this visit could not.

What should you ask your surveyor?

• Could you see the crown on this side, the other side, or only canes against the fence?
• Did you cross the boundary at any point?
• Please confirm you are not giving a management category while the side is unknown.

What are the typical next steps?

1. Do not fill in the side of the fence from memory of the viewing.
2. Ask the solicitor to raise the location with the seller.
3. Do not cut the boundary growth to make the photograph neater.

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

Which pages should you read next?

• Japanese knotweed is growing on the far bank, beyond the garden fence. Why does the survey of this plot not become a management plan for the bank?
• A new patio has been laid where knotweed was treated. Can the survey see rhizome through the slabs?
• If the seller offers an indemnity policy instead of repairing a rating 3, what have they not done?
• Guide: What should you do if a survey mentions Japanese knotweed?
• All UK home survey questions

Sources

• RICS: New Japanese knotweed standard comes into effect (Property Journal, 21 March 2022)
• RICS: Japanese knotweed and residential property, RICS professional standard, 1st edition, effective 23 March 2022
• GOV.UK: How to stop Japanese knotweed from spreading (updated 12 February 2026)