Damp and moisture meters
A tiled bathroom sits on a timber floor that was not opened. What of the joists under the tray is unknown?
The joists under the tray are unknown in the ways that matter. The surveyor saw a tiled bathroom and did not open the floor, so the joists, the deck and the underside of the shower tray were not examined. Tiles can hide a soft tray, a failed seal or timber that has been wet for a long time. A firm floor underfoot is not proof of sound joists. No board was lifted and no ceiling below was opened. The report notes a concealed bathroom floor. It has not decided the joists are dry or free of decay.
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 tray depends on its waste, its upstands and the seals at the screen. Water that escapes does not always appear on the landing. It can track along joists, sit under the tray and stain a ceiling only later. A home survey does not break out a finished bathroom to chase that path. Still unknown are the condition of the timber, the joist ends in the wall, any notching for pipes, and whether the tray is properly supported. Tiles are a finish, not a view of the structure.
Tell your solicitor the bathroom floor is an unopened limit, not a clear result. If the joists must be known, agree a hatch or a lifted board with the owner, or a later inspection once the floor can be opened. The survey has not specified repairs and has not said the tiles must come off. A lender should be told only that the structure under the tray was not seen. Do not turn a neat bathroom into evidence that the timber is sound.
What should you ask your surveyor?
- Is there a hatch, or a ceiling stain below this bathroom, that the report already notes?
- Can the tray be judged for movement, or do the tiles make that impossible?
- Were the waste and the screen seals visible, or were those hidden as well?
What are the typical next steps?
- Treat the joists under the tray as not inspected.
- Ask the seller about leaks, ceiling stains and any boards already replaced.
- If the timber must be proved, arrange an opening this visit did not make.
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 dry ceiling below mean the joists are dry?
No. A ceiling can look clean while the deck under a tray is damp, because water has not come through yet or because the plaster was painted. The survey did not open either face. A dry ceiling is not a test of the joists. It only means that surface showed no stain on the day of the visit.
Should the bathroom be stripped because the floor was not opened?
No. Leaving a floor unopened is a limit on the inspection, not a finding that the tiles or the joists have failed. The survey records that the structure under the tray is unknown. It does not order the bathroom to be taken apart. Open it only if you need that answer, and in a way that can be made good.