Radon

Why does a radon test take about three months and two detectors?

Because the Action Level is an annual average, not a moment on the day of the survey. UKradon describes the home test as two detectors, one in a bedroom and one in a living room, left for three months. A home survey visit lasts hours, not a season. The surveyor cannot carry that test inside an ordinary instruction.

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?

Short readings jump with the weather and with how the house is used. The three-month placement is how those jumps are averaged. Putting both detectors in the same room, or only in a cellar, does not match the method UKradon describes for the Action Level comparison in a home.

If you are buying, you may not have three months before exchange. That is a timing problem, not a reason to pretend the map is the test. You can still commission a proper test and decide, with your solicitor, what happens if the result arrives late. There is no RICS rule that the seller must pay for the detectors. This page does not invent a detector price.

What should you ask your surveyor?

Has anyone started a three-month test, and in which rooms?
Are you being asked to treat a weekend meter as the Action Level?
Will the result exist before you are legally committed?

What are the typical next steps?

If radon is a concern, order the test UKradon describes rather than a second walk-through.
Tell your solicitor the date the result is due, so the contract timing is a choice and not a surprise.
Do not let a seller’s “we aired the house” stand in for the detectors.

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

Can the surveyor place the detectors while they are there?

Only if that was agreed as an extra, and even then the result is not ready on the day. The inspection itself still is not a radon measurement.

Does a new-build warranty include a radon test?

Not as a rule stated on this page. Protection in new building work is a regulations question. A warranty is not a three-month average.