Creating a safe and dry basement by overcoming the conflict between waterproofing and gas proofing

Basement living and working is frequent in the UK, with barely a week going past without mention in the press of planning applications for a ‘superbasement’ or ‘billionaire’s bunker’. All basements are at risk of containing high levels of radon, the naturally occurring radioactive gas, regardless of their geographic location. Since 1999, designers and contractors have been steered towards the use of internally fitted cavity drain membrane systems for basement waterproofing. Such systems are based on air gap technology, however, and are not appropriate for gas proofing, rather they may inadvertently increase radon concentrations in the property. This paper explores the conflict between best practice waterproofing and effective gas proofing, and a process that was developed to solve the dilemma, along with case studies of successful installations.