Radon
The report mentions a radon sump next to a fan that was off. Has a level the survey did not measure been tested, or only named?
No radon level was measured. A radon sump beside a fan that was off is equipment noted on the visit, not a reading. The survey did not run the fan to produce a figure. A sump and a fan are parts of a mitigation system that may or may not be doing anything while the fan is stopped. The report records the hardware and that the fan was off. It has not tested a level and it has not decided the house is protected.
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 radon sump is a void, usually under the floor, from which air can be drawn so that soil gas is pulled away rather than into rooms. The fan is what creates that draw when it runs. A fan that is off on survey day may be failed, switched off, or simply between duties, and the visit cannot tell those apart. No level was measured. Naming the sump does not show underfloor continuity, fan performance or the air in the rooms.
Ask the solicitor for any radon report, fan service record and note of who owns the system. A radon specialist can test levels and check the fan if you want that done. It was not done here. Tell a lender the sump and a stopped fan were named and that no level was measured. Do not describe the house as mitigated just because a sump exists beside a fan that was not running.
What should you ask your surveyor?
- Was the radon sump only named, with the fan off?
- Did this visit measure any radon level?
- Has mitigation been left unproved while the fan was stopped?
What are the typical next steps?
- Treat the sump and the stopped fan as named equipment.
- Ask the solicitor for any radon report and fan service note.
- Commission a radon test if a measured level is needed.
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 an area map show the level in this house?
No. Maps indicate where radon is more or less likely in an area. They do not measure this sump, this fan or the air in these rooms. The survey did not measure a level either. Use a proper test if you need a house result, and keep the map as background rather than as a reading.
Who services a radon fan if the system stays?
Usually a specialist contractor, sometimes under a previous owner's arrangement that may not transfer. The survey did not service the fan and did not measure radon. Ask the solicitor whether a maintenance contract exists and whether it can pass to you. A fan that was off is not a serviced fan.