Radon Barriers Explained: Protecting Buildings from Underground Gases
Radon is a naturally occurring radioactive gas released by rocks and soil. You can't see it or smell it, but long-term exposure is the UK's second-largest cause of lung cancer after smoking. It enters buildings through floors, gaps and service penetrations — and in designated radon-affected areas, building regulations require protective measures in new builds and extensions.
Do You Need Radon Protection?
Check the UK radon map (ukradon.org) for your postcode. In affected areas, new buildings need basic protection (a radon barrier across the footprint) and higher-risk areas need full protection (barrier plus a ventilated sump or void). Existing buildings in affected areas can be tested cheaply with a passive detector.
The Problem with Sheet Radon Membranes
Traditional radon protection is a polyethylene sheet — and its weakness is the same as any sheet membrane: every joint, lap, tear and pipe penetration is a potential leak path for gas. Radon doesn't need a big hole; it migrates through the smallest gaps under pressure differences.
The Liquid-Applied Alternative
Passive Purple acts as an airtight, seamless radon barrier: spray- or brush-applied across floors, walls and junctions with no joints to fail. It bonds to brick, block, concrete, timber and steel, follows complex details, and does three jobs in one coat — airtightness, vapour control and radon protection. Detail joints and penetrations with airtight tape and airtight sealant for a continuous gas-tight envelope.
Why Airtightness and Radon Protection Go Together
Radon entry is driven by the pressure difference between the ground and your building — the same uncontrolled air leakage paths that waste heat also pull radon in. Sealing the envelope addresses both at once: lower bills, better air quality, and a measurable reduction in radon ingress.
We're members of the Radon Council and can advise on the right specification for your project. Shop radon barrier membranes → or get in touch.