Japanese knotweed
What should you ask if Japanese knotweed is next door and within three metres of the boundary?
Ask whether the surveyor is reporting management category D, which the 2022 journal uses for infestations seen off site within three metres of the boundary. Ask what they could see of the boundary, and what a specialist would be asked to do when the plant is not on the seller’s land.
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 older seven-metre habit was cut back in the 2022 standard. The journal says the distance was reduced to three metres and sits under category D, which is a report, not the same action categories as plants inside the boundary that are damaging a structure or blocking amenity. You cannot usually instruct work on a neighbour’s garden as a condition of your purchase. GOV.UK’s spreading rules bind the person who has the plant. They do not let a buyer serve a notice the survey has not drafted.
Your solicitor can ask the seller what they know and can tell you what the property information form said. The survey does not replace that form. If the lender has a rule about off-site knotweed, ask the lender. RICS has not published a universal lender ban in that journal.
What should you ask your surveyor?
- Is this category D, and how far from the boundary was the plant you saw?
- Could you enter the neighbour’s land, or only see it over the fence?
- What can a specialist say if the plant is not on the property you are buying?
What are the typical next steps?
- Do not trespass to spray a neighbour’s knotweed.
- Tell your solicitor what the surveyor saw and where.
- Ask the lender whether off-site knotweed within three metres is something they want reported. Get the answer from them.
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 three metres include the plant’s underground growth?
The journal is about infestations seen off site within three metres. The surveyor reports what was seen. They have not excavated the neighbour’s rhizome.
Is category D the same as category A?
No. A is visible material damage to a significant structure. D is a report of a plant off site within three metres. Do not brief a builder as if the house is already damaged.