Radon Testing: what happens if my property is in a radon affected area?

Radon testing of a property you are buying is highly advisable if your environmental search and/or radon search reveals that your property is in a radon affected area.

Even if your property only has an estimated probability of 1-3% of being above the action level, the chilling fact that radon kills double the number of people in the UK compared to those killed by drink driving should be enough to encourage you to get a full test.

Because the test itself takes 3 months - and then requires a further 6 weeks to process the result - this can result in buyers having to negotiate retentions with sellers to cover remediation action. This is discussed below as well as information for those buying New Build properties.

Need advice on radon testing? Just call one of our experts on 0333 344 3234

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What happens in a radon test?

  • You order a home measurement pack through Public Health England; you can do this by visiting www.ukradon.org/services/orderdomestic
  • You then receive 2 detectors up to 10 days after ordering, one for the living area, one for a bedroom. The detectors come with placement and other instructions.
  • The test takes 3 months, to allow for fluctuations in radon levels. After 3 months, you post the detectors back using the pre-paid envelope provided.
  • After the detectors have been analysed, PHE posts the results back to you within 6 weeks.
  • Depending on the level of radon found, PHE will give you advice, including, if required, information about the best remedial method.

I am a buyer, how should I proceed?

You should ask the current owners if they have completed a 3 month radon test - if they have, you should ask them for the report. If they have not, you should discuss a retention with your solicitor and test when you move in.


I am a seller, how should I proceed?

If you have previously tested a property, you should find the result - you can contact your test provider if necessary. If you have not tested, the new owner may be advised to do so when they move in. You and your solicitor should be prepared to be asked about a retention.

Retention - what do I need to know?

  • A retention is a sum of money held back from a sale to help with any required remedial costs.
  • Typical remediation of a domestic radon issue costs around £1,000.
  • A typical retention for this purpose is between £500 - £2,000.
  • One of the solicitors holds this money for an initial period of 6 months to allow time to move in, the 3 month test, analysis and receipt of the report.
  • If the test returns the result that radon levels are below the action level, the money retained goes to the seller.
  • If the test states that radon levels are above the action level, the money pays for remedial works and a timescale is agreed to allow for the works and a further test.
  • Any surplus money is returned to the seller.
A retention may not be suitable when a buyer is planning to carry out major building work as soon as they move in or if they are not planning to move in straight away.

What if I am buying a New Build home?

Radon Gas Testing
When required by building regulations and associated guidance, new build properties in radon affected areas are expected to have radon protective measures installed when they are built.

The guidance recommends specific protective measures depending on the construction of the building and whether 'Full' or 'Basic' radon protection should be provided.

You can find out whether you should have full or basic protection by asking your builder or by doing a radon search. The radon search will state whether the radon protection expected is 'basic' or 'full'.

Basic radon protection - protection is provided by a damp proof membrane modified and extended to form a radon-proof barrier across the ground floor of the building.

Full radon protection - comprises a radon-proof barrier across the ground floor and provision for subfloor depressurisation (a radon sump) or ventilation (a ventilated subfloor void). It is important to realise with full radon protection that the sump is not activated when the house is built. It is capped and available for use as a secondary measure in case the radon-proof barrier is insufficient for reducing radon levels below the Action Level 200 Bq m-3.

What happens when I move into my New Build home?

PHE recommend doing a 3 month radon test in your new home during the first year of occupation as it is not guaranteed that your radon level will be less than the action level. If the radon test result is higher than the action level and you have full protection built in, these additional measures can be used to reduce radon levels further.

Radon sump. Activate - add a fan to the sump pipe OR passive - the cap can be removed and a pipe added to above the eaves of the roof.

Increased under-floor ventilation. Add a fan to increase ventilation to the under-floor void.

If only basic protection is fitted a radon sump of underfloor ventilation can be fitted. Once you have made these changes - test again to ensure that the radon levels are reduced sufficiently.

What if I am not occupying my property?

Radon testing is only effective if you are actually living in a property and for a 3 month period. You should always test out your permanent residence if it is listed as being within a radon affected area.

What if I my property is buy to let?

The Housing Health and Safety Rating System Regulations list radon as a hazard - this means that properties in radon affected areas must have a hazard assessment carried out on them. You should contact your local council for further details about this.

What if I want to significantly upgrade or extend my property, which is in a radon affected area?

You should seek professional advice from your local council's Building Control or Environmental Health Department.

Need further advice? Just call us on 0333 344 3234 or email us at help@samconveyancing.co.uk.

*Fixed Fee – No Sale No Fee – On all Mortgage Lender Panels


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