Japanese knotweed
A raised sleeper bed covers the spot where a crown was reported. What of that crown is now hidden?
The crown itself, and the ground it was reported in, is now hidden. A raised sleeper bed covers that spot, so the survey could not see the crown, the soil under the timbers, or any rhizome and regrowth beneath the bed. What remains visible is the bed, not the plant part that was previously named. The report records the cover. It has not inspected the crown and has not decided the plant has gone.
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?
A crown is the woody base Japanese knotweed grows from. Covering it with sleepers and soil takes it out of a visual inspection without removing it. Stems can be absent above a bed while the crown and rhizome persist underneath, and a tidy surface is not treatment. The surveyor cannot probe through the raised bed on a home survey and call that a clearance. The hidden part is the whole of the reported crown and the ground that holds it.
Ask the solicitor for any knotweed management plan, treatment record and guarantee that names this spot, and compare them with the bed that now covers it. A lender may want a specialist to say whether the crown is still there, which this visit cannot do. Do not lift the bed as a casual check during your viewing. Keep any later specialist report separate from this note that the crown is concealed.
What should you ask your surveyor?
- Which part of the garden does the sleeper bed cover?
- What earlier report named a crown at that spot?
- What wording says the crown itself was not seen?
What are the typical next steps?
- Read the bed as cover, not as clearance.
- Ask the solicitor for any management plan naming that spot.
- Keep a specialist’s later look separate from this report.
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 bare soil beside the bed clear the crown?
No. Bare soil beside the sleepers is not the spot the bed covers. The crown was reported under that raised bed, and that ground was not seen. Growth, or the lack of it, at the edge does not identify what is under the timbers. The survey has not decided the crown is absent.
Can last year’s herbicide letter stand in for a look?
A herbicide letter, if you have one, is a treatment claim. It is not a view of the crown under this sleeper bed. The visit did not see that crown and did not verify any contractor’s work. Ask the solicitor for the plan and the guarantee. The report only records that the reported spot is now hidden.