Gas is generated underground in many different conditions. For the most part it does not constitute a hazard, as gas which percolates to the surface dissipates under normal atmospheric conditions, preventing dangerous concentrations form developing. However when buildings are constructed on gas contaminated land, gas can seep into buildings through openings, construction joints, cavities and service penetrations to reach dangerous concentrations.
The common occurring gases for which protection is required and is achieved by using gas membranes, a gas barrier or a radon barrier are:
Methane: forms an explosive mixture in air at levels of 5-16% by volume;
Carbon Dioxide (CO2): a toxic, asphyxiating gas; maximum permissible levels 0.5% by volume for long term exposure and 1.5% by volume for short tem exposure;
Radon: a radioactive gas associated with increased levels of cancer. Radon gas is tasteless and odourless and is highly hazardous for human beings hence the importance of an effective radon barrier.
Other hazardous gases include carbon monoxide, hydrogen sulphide and hydrogen.
There are three main sources of gas contamination: Brownfield sites, Landfill and Natural occurrence. Building regulation C2 states ‘precautions shall be taken to avoid danger to health and safety caused by substances found on or in the ground to be covered by the building.’ (Scotland see regulation 16)
A high performance gas resistant membrane must be installed across the whole footprint of the building. Where rates of gas are high it will be necessary to install a venting system in the gas membranes, which provides a path for the gas to disperse into the atmosphere. (Product data available upon request.) Installing gas membranes, a gas barrier or a radon barrier is essential from a safety point of view to remove the risk from hazardous gases.
Gas Membrane Installation for New NHS Hospital in Girvan,
Scotland for Barr Construction
Reeve-Tec Membranes Ltd offers a full installation service for gas membranes including a gas barrier and radon barrier. Our in-house specialised installation service enables us to deliver a ‘right first time’ system for domestic and commercial projects.
To view Reeve-Tec Membranes Standard installation procedures click here.
|Steel Stanchion Detail||Commercial Project||Steel Stanchion Detail|
|Welding Technique||Door Threshold Detail||Corner Detail|
Reeve-Tec Membranes Ltd recommends for commercial projects the gas membrane to be installed in one operation, this minimises the risk of damage and reduces the costs of installation.
As for domestic projects gas membranes should be installed as a perimeter and infill operation.
Perimeter & Infill Installation: a width of gas membrane is installed to the perimeter along with any load bearing internal walls. Immediately before the floor screed is laid the gas membrane is installed within the building and heat welded to the perimeter membrane.
|Perimeter Detail||RTEC4 Gas Membrane for Housing Project|
Complete Lineout Installation:
When used in conjunction with high impact floor screeds we are able to install the membrane over the entire footprint of the building in one operation.
|Complete Lineout of Gas Membrane|
Gasflow venting systems: Reeve-Tec Membranes Ltd can offer a full design for Gasflow venting systems. Gasflow venting systems are normally supply only contracts due to construction methods this reduces installation costs. Our Project Managers will be on site to assist during installation to enable us to certify the works.
Integrity Testing Reeve-Tec Membranes Ltd can offer on site integrity testing for all gas membrane installations. An independent party will visit site and issue a certificate on completion.