Radon Protection in New Construction

New buildings offer a unique opportunity to install radon protection at minimal additional cost (typically 0.1–0.5% of total construction budget).

Retrofitting a mitigation system later costs 5–10 times more than building in protection from the start. Prevention is always better than cure.

Since 2020, Spain's Technical Building Code (CTE) includes Document DB-HS6 on radon protection. It establishes a reference level of 300 Bq/m³ for indoor radon.

New buildings in Zone II (radon potential > 300 Bq/m³ in more than 10% of buildings) must include a radon barrier. In Zone I, ventilated air chambers or barriers are required depending on building type and ground contact.

Required measures include: gas-tight membranes, sealed service penetrations, ventilated sub-floor chambers, and in some cases active depressurization systems.

In England and Wales, Building Regulations (Approved Document C) require radon protection in areas where 3% or more of homes exceed the Action Level of 200 Bq/m³.

Basic protection (a radon-proof membrane) is required in lower-risk areas. Full protection (membrane plus radon sump/pipe) is required in higher-risk areas where 10% or more of homes exceed the Action Level.

The BRE radon atlas defines protection requirements on a grid-square basis.

EU Directive 2013/59/Euratom requires member states to establish national action plans including building code provisions for radon in new construction.

Best practice across the EU includes: identifying radon-prone areas, requiring protection measures in new construction, and setting reference levels not exceeding 300 Bq/m³.

Countries like Ireland, Finland and the Czech Republic have well-developed building code requirements that go beyond the minimum directive requirements.

Radon barrier membranes: gas-tight membranes installed beneath the floor slab, properly sealed at joints and penetrations. Materials must meet specific gas permeability standards.

Radon sumps: gravel-filled chambers beneath the slab connected to exterior vent pipes. Can be passive (stack effect) or active (fan-assisted) depending on radon levels.

Ventilated sub-floor voids: raised floor construction with ventilated air space below. Effective but increases construction complexity and cost.

Positive pressurization: mechanical ventilation systems that maintain slight positive pressure indoors to prevent soil gas ingress. Used in combination with other measures.