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Check radon gas risk for any UK property with BGS radon potential maps and Building Regulations requirements.
Updated: periodically as BGS revises mapping · Last checked by Maplify: July 2026
This layer maps British Geological Survey radon potential at 1km grid resolution, showing the percentage probability of homes exceeding the 200 Bq/m³ Action Level, alongside detailed Radon Affected Areas identifying zones requiring protection measures under Building Regulations Approved Document C.
Radon is a naturally occurring radioactive gas from uranium decay in rocks and soil, particularly granite and some limestone geology, and can accumulate to harmful concentrations in poorly ventilated indoor spaces.
Radon exposure is linked to increased lung cancer risk, and Building Regulations mandate specific protection measures for new construction in higher-risk areas — measures that add cost and must be designed in from the outset rather than retrofitted. Buyers, self-builders and developers check this layer to understand both health risk and construction cost implications.
For existing homes in higher-risk areas, testing and retrofit remediation such as a radon sump are widely available and relatively low-cost compared with the potential health risk of prolonged exposure.
Lower Risk (< 1%)
Less than 1% of homes above the Action Level. Radon protection not required for new builds.
Intermediate Risk (1–5%)
Basic radon protection membrane required for new buildings.
Higher Risk (5–30%)
Full radon protection including a passive sump required.
Highest Risk (> 30%)
Enhanced active radon protection and post-construction testing mandatory.
New buildings in intermediate risk areas require a basic radon protection membrane; higher risk areas require a full radon sump with passive vent; the highest risk areas mandate active fan extraction and post-construction testing to confirm the measures are effective. These requirements are checked as part of Building Regulations approval, separate from planning permission itself.
Known high-risk areas in the UK include Cornwall and Devon, the Peak District, Somerset and the Cotswolds, the Yorkshire Dales, Cumbria and Aberdeenshire, largely correlating with granite and certain limestone geology.
Check the BGS Radon Potential rating for the specific site before designing a new build.
Incorporate the appropriate radon protection measure — membrane, sump or active extraction — based on the risk band.
Commission post-construction radon testing in the highest risk areas to confirm effectiveness.
Test existing homes in higher-risk areas and consider retrofit remediation if elevated levels are found.
Check the wider Geology & Ground Risk layer for the same site for the fuller ground risk picture.
This is general guidance, not professional or legal advice — confirm specifics with the relevant authority or a qualified professional.
Self-Builders
Design in the appropriate radon protection measure from the outset.
Property Developers
Budget for radon protection in new-build schemes in higher-risk areas.
Property Buyers
Understand radon exposure risk before purchasing an existing property.
Surveyors
Factor radon potential into building survey reports.
Radon checks are often run alongside these related searches.
What is radon and why does it matter?
Radon is a naturally occurring radioactive gas from uranium in rocks and soil. Long-term exposure to high concentrations indoors is linked to increased lung cancer risk, making radon protection a Building Regulations requirement in higher-risk areas.
How do I check radon risk for a property?
Search the property on Maplify and enable the BGS Radon Potential layer to see the percentage probability of homes exceeding the 200 Bq/m³ Action Level in that area.
What Building Regulations protection is required in high radon areas?
Basic protection (radon membrane) applies in intermediate risk areas; higher risk areas require a radon sump with passive vent; the highest risk areas mandate active fan extraction plus post-construction testing.
Which UK areas have the highest radon risk?
Cornwall, Devon, the Peak District, Somerset, the Cotswolds, the Yorkshire Dales, Cumbria and Aberdeenshire have notably elevated radon levels due to granite and limestone geology.
Can I test my existing home for radon?
Yes — the UK Health Security Agency and private providers offer radon testing kits, and remediation such as a radon sump can be retrofitted if elevated levels are found.
Access BGS radon potential maps and Building Regulations requirements instantly.
| Provider | British Geological Survey |
| Geometry type | Raster (1km grid) |
| Coverage | Great Britain |
| Update schedule | Periodic, as BGS revises radon mapping |
| Reference date | July 2026 |
| Licence | Open Government Licence v3.0 |
