Subsidence, settlement and heave
The surveyor has named a willow or a poplar, rather than only a large tree. What does the species add?
It adds a better description of what they believe they saw, and it does not add a water-uptake figure this report must not invent. An unnamed large tree is a vaguer note, not a different diagnosis. In both cases the survey does not test the soil or monitor any crack, and a species name is not a calculation.
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?
Willows and poplars are often mentioned because they are associated with high water use on clay, in the same broad conversation as other large trees. The Association of British Insurers discusses vegetation and subsidence in general terms. Subsidence, in that guidance, is downward movement of the ground. Naming the tree does not measure how much water this specimen takes, how far its roots reach, or whether this crack was caused by it. Those numbers are not in the inspection, and they should not be guessed in a letter to the seller.
If the surveyor has only written “a large tree”, ask whether they could identify it and, if not, say that the note stays unidentified. Do not look up a forum figure for a poplar and paste it under their sentence. Do not treat a willow as automatic underpinning. Ask what damage was seen, on what soil they believe the house stands, and whether that soil belief is from a map or from a hole. A desktop label is not a soil test. If a specialist later names the tree differently, use their identification and still do not invent litres.
What should you ask your surveyor?
- Are you confident of the species, or is willow or poplar your best visual guess?
- What crack or distortion are you actually linking to the tree?
- Please confirm you are not giving a water-uptake figure. I will not add one.
What are the typical next steps?
- Quote the species only as the surveyor wrote it.
- Do not download a root-radius or a litres-per-day figure and call it part of the report.
- If the tree matters to an insurer, send the wording you have and let them ask for their own specialist.
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 an unnamed tree safer than a named poplar?
No. Missing the name is a weaker description. It is not a clean bill. Ask for a name if the surveyor can give one.
Does a willow mean heave if it is later cut down?
Heave can follow tree removal on clay. The species name does not tell you it will happen here. The survey has not tested the soil.