Monarflex Gas barriers

Monarflex Gas barriers


Gas from contaminated ground

Gas is generated in the underground and for the most part it percolates to the surface and dissipates under normal atmospheric conditions. Under these circumstances the gas does not constitute a health hazard. However, when buildings are constructed on gas contaminated land, it will seep into buildings through openings, construction joints, cavities and service penetrations to reach a dangerous concentration with a serious health hazard to the inhabitants of the house as a consequence.

A high concentration of methane gas can be naturally occurring dependent on the geological structure but is furthermore often found on ground that:

  • previously has been utilised for industrial processes ex. chemical factories by spillage of gas-generating chemicals and heavy hydrocarbons
  • has been used as landfill where the breakdown of organic material by micro organisms under anaerobic conditions produce landfill gases of methane and CO2. A thorough site investigation is usually required to determine the concentration

The health hazard

A high concentration of methane gas in a building must be controlled to avoid explosion by ignition. There are several examples of explosions in houses caused by high concentrations of methane gas. One of the most cost-effective methods to prevent gas from entering the house is to use a high performance  gas resistant membrane.

The membrane must form a completely tight barrier between the ground and the foundation of the house. The installation of the barrier must be done carefully so the gas cannot enter via overlaps and pipe penetrations that are not carefully sealed. To prevent a gas built-up beneath the membrane, it is necessary to create a ventilation system so the gas can disperse into the atmosphere

Monarflex product range

The gas membranes from Monarflex a/s are developed specially for contaminated ground caused by chemicals or high concentrations of methane gasses. The products are all reinforced for higher strength and have a thick aluminium foil as a dependent gas barrier. The membranes are resistant to most chemicals. Produced from LDPE, installation in low temperatures is possible without cracking.

We recommend the use of MONARFLEX® Reflex Super and MONARFLEX® RAC for protection of houses against gas penetration. Both membranes are high performance membranes with unique tensile strength and puncture resistance properties.

Gas Membranes Application Area
MONARFLEX® Reflex Super High performance gas membrane for all purposes
MONARFLEX® RAC High performance gas membrane - recommendable if there is traffic on the membrane




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Monarflex contact details

Monarflex s.r.o.
Továrenská 1
943 03 Štúrovo

Slovak Republic

Phone + 421 36 7563865

UK & Ireland

Please visit the dedicated website at

Tel: 0161 8654444 (UK office)

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