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

Technical Guidance Document C (TGD C -Site Preparation and Resistance to Moisture) (2023 Amendment) of the Building Regulations has been updated to reference the most up-to-date radon map published by the Environmental Protection Agency (EPA). This updated Technical Guidance Document C will apply to all new buildings and extensions commencing construction from 1 October 2023.

The amendment to the Technical Guidance Document C aims to ensure all new buildings 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 Technical Guidance Document provides that a radon resisting membrane is installed in the floor build-up.