Damp and moisture meters
The bathroom fan stopped when the light was switched off and no run-on was observed. What overrun was not demonstrated?
No overrun was demonstrated. The bathroom fan stopped when the light was switched off, and the surveyor did not see it run on after that. An overrun, if one is fitted, is the period the fan keeps turning once the light is off. That period was not shown, so the report cannot say a timer works, cannot say how it is set, and cannot say there is no timer hiding in a failed switch. What was observed is a fan that stopped with the light. The overrun itself was not demonstrated.
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?
Bathroom fans are often wired to the light so they start when the room is in use. A run-on should keep extracting after the light is out, while moist air is still in the room. If the fan dies with the switch, that continued extract was not seen. The cause might be no timer, a timer set to nothing, or a failed unit. The survey did not open the wiring and did not test the circuit. It watched the fan stop with the light.
If you need to know whether an overrun can be set, ask an electrician as a separate instruction. The home survey has not done that test and has not certified the fan. Tell the solicitor, if the point matters to the purchase, that no run-on was observed when the light went off. Do not write into the report a run-on you did not see, and do not treat a fan that stops with the light as a tested electrical installation. The limit is the missing demonstration.
What should you ask your surveyor?
- Did the fan stop as soon as the bathroom light was switched off?
- Was any overrun seen, even a short one?
- Did you test the fan electrically, or only watch it with the light?
What are the typical next steps?
- Record that no run-on was observed when the light went off.
- Do not add an overrun the visit did not see.
- Ask an electrician if you need the fan tested.
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
Could a timer still be there even though the fan stopped?
Yes, it could, and the survey has not ruled that out. No overrun was demonstrated, which is not proof that a timer was never fitted. A failed or unset timer can look the same as no timer when all you do is switch the light off. The report stops at what was observed.
Does the fan stopping mean the bathroom has no ventilation?
No. The fan ran while the light was on, so extract during use was seen. What was not demonstrated is overrun after the light went off. The survey has not measured the air the fan moves and has not condemned the whole bathroom. The gap is the run-on.