Timber decay and woodworm
The ground floor is suspended and the surveyor did not enter the void where sleeper walls would stand. What remains unknown underneath?
Because the surveyor did not enter the void under this suspended floor, the sleeper walls remain unknown. So do the joist ends, the oversite and the ventilation that a view under the boards would have recorded. Sleeper walls are the low walls that carry the joists between the main walls. None of that fabric was walked. A look from the rooms above cannot invent their condition. What stays unknown underneath is the support the floor is actually standing on.
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?
Air bricks outside, a firm floor underfoot and a dry carpet are not a view into the void. Those dwarf walls can be crumbled, blocked by debris, or perfectly adequate, and the room will not say which. Read the report as an access limit. It is not a clean bill for the timbers, and it is not a diagnosis of rot. The unknown is the point of the sentence. It should stay unknown until someone has actually been underneath.
Getting in means a hatch or a lifted board, and room enough to see, which the seller must allow and which may still be impractical. If that happens it is a further instruction, not a paragraph already written. Do not let a damp quotation assume the sleeper walls have collapsed, and do not let anyone assume the floor was passed. The visit stopped at boards it did not lift.
What should you ask your surveyor?
- Why was the void not entered, and is there a hatch that could be used?
- What, if anything, could you see through an air brick or a gap without going under?
- Which parts of the floor structure are you leaving undescribed?
What are the typical next steps?
- Treat the sleeper walls, the joist ends and the oversite as not inspected.
- Do not price repairs to dwarf walls that nobody has seen.
- If entry is possible, agree a further look with the seller before you rely on the floor.
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 a solid feel underfoot mean the sleeper walls are sound?
No. Feel is not a view into the void. The surveyor did not enter, so the sleeper walls were not seen and cannot be passed as sound.
Has the oversite under the floor been judged dry?
No. The oversite is in the void that was not entered. Dry rooms above do not describe the ground beneath the joists.