The occurrence, extent and concentration of gases such as Radon / Methane and Carbon Dioxide are essential considerations in the design and installation of any waterproofing system as applied to the foundation zone of any structure.
Methane and Carbon Dioxide are commonly found naturally close to organic strata such as those containing slate, coal seams and peat areas. High concentrations can also be found at or in close proximity to Brownfield sites which were previously occupied by Industries processing for example, Hydrocarbon materials such as coal, oil etc. Concentrations and traces of these gases with their associated impurities can also be found in locations associated with Landfill sites where rotting vegetation and putrescibles are a major source of organic leachate, lixiviant and methane.
Gases are generally lighter than air and migrate upwards and laterally until they either form concentrations in occluded pockets within soil masses or foundation areas or they naturally vent and disperse in to the atmosphere.
Obviously the concentration and trapping of gases in the foundation zones of areas where structural development is to be considered poses a potentially hazardous situation and health risk. It is therefore important and a requirement of law that precautions are taken to avoid any dangers which may be associated to Health and Safety as a direct consequence of substances which are found in the ground over which building or structural work is intended.
Membrane systems, which constitute a permanent barrier as well as control the flow to an otherwise uncontrolled migration and concentration of gases are essential elements to the long term Health and Safety of any development and have now become a requirement by law. These durable membrane systems prevent the passage of gases through the foundation zone and into the building through fissures, construction joints and other migratory pathways.