Radon and Conveyancing: What Buyers and Sellers Need to Know

Author: Kayleigh Kryulko-Coombe, Consultant Residential Property Solicitor | Read time: 6 minutes | Last updated: 29 June 2026

Radon can be a key consideration in a property transaction. Understanding how radon gas arises, how searches report risk, and what to do if levels are elevated will help you move forward with confidence. Below, we outline the essentials and explain how Setfords’ conveyancing team, including solicitor Kayleigh Kryulko-Coombe, can protect your position throughout. 

Key takeaways

• Radon is a naturally occurring radioactive gas that can enter any property.
• Certain areas of the South West, Wales, and the Peak District carry a higher risk due to local geology.
• Environmental searches reveal whether a property sits in a radon-affected area, but only a UKHSA-approved long-term test can confirm the actual level in that specific home.
• Sellers must disclose any radon test results or existing mitigation systems in pre-contract enquiries.
• If levels exceed the UK Health Security Agency’s reference level of 200 Bq/m³, mitigation is advised.
• A radon finding doesn’t have to stall a transaction. Retentions, price adjustments, and agreed remediation timescales are all established ways to keep conveyancing moving.

Understanding radon and why it matters in conveyancing 

Radon is a colourless, odourless radioactive gas produced by the natural breakdown of uranium in soils and rocks. It can enter buildings through gaps in floors, service penetrations, and foundations. Properties with basements, cellars, or limited underfloor ventilation can be more susceptible to radon in home environments. Certain parts of the UK, including areas of the South West, Wales and the Peak District, are more likely to be designated as a radon-affected area due to local geology.

Prolonged exposure to elevated radon increases the risk of lung cancer. The UK Health Security Agency (UKHSA) reference level is 200 becquerels per cubic metre (Bq/m³). Above this threshold, action to reduce levels is advised. Even below 200 Bq/m³, sensible ventilation and ongoing monitoring may be recommended. Buyers and lenders may view a house with radon differently, so early clarity helps keep conveyancing on track.

Radon checks and searches during conveyancing 

During conveyancing, radon is typically screened via environmental searches. These desktop reports draw on the UKHSA maps and the UK Radon website to indicate whether a property is within a radon affected area and the estimated percentage of nearby homes likely to exceed the reference level. Local authority searches can also reveal whether the property is within a radon affected area but do not usually provide any accurate radon data, so the environmental search is the key document for the initial assessment. 

Results will commonly state either that the property is not in a radon affected area or that it is within one, sometimes with banded risk, for example up to 1%, 1–3%, 3–10%, 10–30% or more of homes likely above 200 Bq/m³. If a result flags risk, further steps usually include arranging to test for radon. A search result alone does not confirm the actual level in the specific property; only a reliable test for radon can do that. 

Sellers should answer pre-contract enquiries accurately, disclosing any radon in home tests, results, or mitigation systems. Buyers should raise targeted enquiries if the environmental search highlights radon gas risk, requesting past reports, installation certificates, and any warranties for mitigation.

If testing is requested, UKHSA-approved long-term tests typically run for three months to provide a dependable average. Shorter indicative tests (around 2–10 days) can assist decisions where time is tight, with follow-up long-term testing after completion if needed. Guidance and postcode checks on the UK Radon website can support these decisions.

Buying or selling in a radon-affected area?

Understand your options and your timeline. Speak to Kayleigh Kryulko-Coombe for a no-obligation conversation.

Speak to Kayleigh

Managing risk if a house with radon is identified 

If elevated radon is suspected or confirmed, options include: 

• Short-term screening to inform negotiations and keep conveyancing timeframes realistic.
• Long-term three-month tests for accuracy and compliance with UKHSA guidance.
• Mitigation measures such as sealing entry points, improving ventilation, installing a positive input ventilation unit, or fitting a radon sump with a fan.

Indicative costs for a standard property range from a few hundred pounds for basic ventilation improvements to £800–£2,000+ for a radon sump system, depending on property type and scope of works. Fan running costs are usually modest. 

Contract solutions that balance caution with progress include: 

• A retention on completion to fund mitigation if post-completion results from a test for radon exceed 200 Bq/m³.
• A price adjustment to reflect anticipated mitigation costs for a house with radon.
• Obligations for the seller or buyer to test for radon and complete remediation within set timescales, with clear triggers, evidence standards (for example UKHSA guidance and any relevant Building Regulations), and responsibility for access and certification.

How Setfords and Kayleigh Kryulko-Coombe can help 

Every transaction is different. Whether you need rapid advice on a flagged environmental search, help drafting a retention clause, or support liaising with your lender, our team can assist. We will guide you through radon gas findings and advise on proportionate protections that keep conveyancing moving. We also recommend that you obtain specific advice on the same from surveyors and environmental specialists who will be able to provide practical solutions to mitigate any risks.

Solicitor Kayleigh Kryulko-Coombe has extensive experience handling radon-related enquiries. We liaise with lenders to understand any conditions or requirements they may have, negotiate retentions or undertakings where a buyer wishes to conduct radon testing post completion, and can align completion timetables with realistic windows to test for radon should a buyer wish for the tests to be conducted prior to exchange and completion. Using resources such as the UK Radon website, we ensure you have clear, practical advice from start to finish, so you can proceed with confidence even when buying or selling in a radon-affected area.