British Standard 8485: 2015 + A1: 2019 Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings, suggests that reinforced low density polyethylene membranes (LDPE) for use in gas control applications, should have a minimum ‘effective’ thickness of 0.4 mm i.e. not including the thickness of any reinforcing mesh. This is on the basis that such a product will be sufficiently strong to withstand the installation process and following trades until covered. While we understand that this Code of Practice does not cover radon membranes, we consider that the same principle on robustness should apply equally to such products.

The BBA has therefore formally adopted a minimum thickness of 0.4mm as a requirement for BBA certification of polyolefin membranes for use in gas control applications, including those certified for the control of radon gas.