Creating a barrier against gas and water

With more deep construction in congested urban areas and an increase in the provision of residential basements, a more detailed assessment is required of the risks inherent in below-ground construction and how these might best be addressed, especially when considering factors other than water ingress such as ground gases and contamination. Strategies for dealing with all external sources of groundwater, surface/flood water, soil gases and contaminants should be determined from the very earliest stages of the planning and design processes for any project involving below-ground structures. Waterproofing systems are materials and methods used to protect a structure from water ingress, and which are often effective as ground gas barrier — ie a barrier between the structure and the ground intended to prevent or impede the ingress of radon, methane and other ground gases and contaminants. There has been much development and use of new materials for waterproofing and understanding how these waterproofing and gas barrier materials are applied to the structure is important when specifying, designing and constructing belowground structures. The relevant codes of practice for each subject offer guidance on how this can be achieved, but does the guidance contained within correspond between documents?