Radon
The report places a cellar, tanking and a radon sump mentioned together and two different systems the sentence does not merge in one paragraph. Which of those were inspected, and which were merely named?
The cellar was inspected only as far as it could be seen. Tanking and the radon sump were named as two different systems the sentence does not merge, not as one tested installation. Tanking is a moisture barrier. A radon sump is a soil-gas measure. The survey did not measure radon, did not test the tanking and did not prove the systems connect. What was seen in the cellar stays a visual note. Performance of either system was not decided.
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?
Tanking is applied to keep groundwater out of a cellar. It can be a membrane, a render or a drained cavity, and a glance does not show which, or whether it is continuous. A radon sump sits under the floor to move soil gas, usually with a fan, and it is not a damp-proofing product. Mentioning both in one breath is a warning not to treat damp control as a radon result. This visit measured neither moisture movement through the tanking nor radon in the air.
Ask the solicitor for tanking guarantees and any radon report or sump specification, and keep them as two files. A damp specialist and a radon specialist answer different questions. Tell a lender the cellar was seen within the limits of access, and that tanking and the sump were not tested and were not merged. Do not claim the cellar is dry because a sump was named, or free of radon because tanking was named.
What should you ask your surveyor?
- Was the cellar only seen, with tanking left untested?
- Was the radon sump named rather than measured?
- Have the two systems been kept unmerged?
What are the typical next steps?
- Read tanking and the radon sump as two named systems.
- Ask the solicitor for separate guarantees and radon papers.
- Do not tell a lender either system was performance-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
Does a dry cellar floor on the day prove the tanking?
No. One dry day does not test a tanking system. Groundwater, leaks and condensation can all be absent on a visit and still matter later. The survey did not test the tanking. It also did not measure radon. Dry flags are a visual note, not a guarantee and not a radon result.
If the sump fan is running, has radon been measured?
No. A running fan shows that a fan is running, not a level in the air. The survey did not measure radon and did not merge the fan with the tanking. Ask the solicitor for any radon report. Equipment in the cellar is not that report, whether the fan is on or off.