The hazards of ground gases must be taken into account when designing and constructing new developments. Ground gas has can be drawn into a building by the pressure of difference that exists between the inside and outside of the building (warm indoor air is less dense than cold outdoor air).
Common ground gases and contaminates
Hydrocarbons – these can be highly toxic and are a derivative of the petrochemical industry. Hydrocarbons are prevalent in areas such as disused petrol stations and post-industrial sites. Most hydrocarbons are carcinogenic and potentially flammable.
Methane – An odourless flammable gas that is explosive when released to the atmosphere at levels as low as 5% and exposed to a source of ignition. Methane is formed wherever there is below ground degradation of organic substances e.g landfill sites, sewage treatment areas, mining localities and peat bogs.
Carbon Dioxide – a colourless, odourless gas that in high concentrations can result in asphyxiation. The gas is formed by the oxidation of carbon compounds such as landfill sites. When carbon dioxide levels reach concentrations of 3% symptoms of headaches and shortness of breath can occur, becoming severe at 5%, with loss of consciousness at 10%. It’s potentially fatal at concentrations of 22% and above.
Radon – a naturally occurring radioactive gas that is odourless and colourless. It is formed where uranium and radium are present. It migrates into any building that is built over the source. If it accumulates in a building at unacceptably high concentrations, it will increase the potential risk of the occupants developing lung cancer.
Current UK construction practice adopts the concept of multiple gas protection measures to form a gas control system. Typically, protection measures increase in number and robustness as the potential risk increases. The gas protection solution is based upon the point scoring system from BS 8485:2007.
At Visqueen, we have developed a comprehensive passive venting solution to facilitate the dilution and dispersal of dangerous gases safely from beneath buildings.
Our solution is used extensively across the UK and the system comprises of:
- Gas Vent Mat
- Gas Flow Fittings
- Gas Vent Outlets including the unique Flood Resistant Gas Vent Box
- Gas Membranes & Gas Resistant DPCs.
The type of passive venting system required is dependent on the building type and the amount of gas flow.
Our complete outlet system consists of the following options:
- Flood resistant gas vent box
- Vent bollards
To find out more about the solutions available from Visqueen Building Products, download the gas Venting
Systems brochure here: