Building Regulations Technical Guidance Document C updated to include latest EPA Radon Risk Map

The Department of Housing, Local Government and Heritage today published an update to Technical Guidance Document C - Site Preparation and Resistance to Moisture (2023 Amendment) of the Building Regulations to reference the most up-to-date radon map published by the Environmental Protection Agency. This updated Technical Guidance Document C will apply to all new buildings and extensions commencing construction from 1 October 2023.

Under Housing for All, the government's housing plan to 2030, Building Regulations (12 parts classified A to M) set out the minimum performance requirements that a new building must achieve. Part C (Site Preparation and Resistance to Moisture) requires that reasonable precautions are taken to avoid danger to health and safety caused by substances (including radon) found on or in the ground to be covered by a building.

The Technical Guidance Document C published today delivers on a strategy action outlined in the National Radon Control Strategy Steering Group, chaired by the Department of the Environment, Climate and Communications.

The amendment to the Technical Guidance Document C aims to ensure all new homes have suitable prevention systems installed by referencing the most up-to-date radon map published on EPA Maps. Where a building is being constructed in a high radon area, the Guidance Document provides that a radon resisting membrane is installed in the floor build-up.

This guidance is for the safety and welfare of people in and about buildings, and for the increased safety and protection of homeowners.

Technical Guidance Document C - Site Preparation and Resistance to Moisture (2023 Amendment).

Radon is a radioactive gas that is formed in the ground by the radioactive decay of uranium, which is present in all rocks and soils. You cannot see it, smell it or taste it. It can only be measured with special detectors. Radon can cause lung cancer when exposed to high levels over a long period of time.

Recognising the scale of radon in Ireland, an inter-agency group, chaired by the Department of the Environment, Climate and Communications was set up in 2011 and tasked with developing a strategy to address radon in Ireland.

The aim of the National Radon Control Strategy (NRCS) is to minimise the exposure to radon gas for people in Ireland and to reduce, to the greatest extent practicable, the incidence of radon related lung cancers. The strategy recognises that an effective response to the radon problem will involve a wide range of measures over a number of years to reduce radon levels in existing buildings and to prevent radon ingress into new buildings.

The Environmental Protection Agency (EPA) is a key agency in the delivery of the NRCS. It hosts www.radon.ie and funds and coordinates research on radon.

In May 2022, the EPA published a high spatial resolution Radon Risk Map of Ireland identifying High Radon Areas, based on the results of a survey of indoor radon measurements and on relevant geological information. The new digital map is accessible via the EPA's interactive website, which is maintained by the EPA. Locations of buildings can be found on this map using Eircode, digital location coordinates or postal address.

Technical Guidance Document C (TGD C) to the Building Regulations provides guidance on the measures which can which be taken during the design and construction of a building, which will significantly reduce the risk of radon concentrations in excess of the National Reference Level. TGD C provides that new buildings in high radon areas should have a radon resisting membrane installed in the floor build-up. New buildings in both high and low radon areas should also be provided with standby sumps (as a potential means of evacuating radon should the need arise) to facilitate remediation.