Gas is generated in the underground and for the most part it percolates to the surface and dissipates under normal atmospheric conditions.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 thatpreviously has been utilized for industrial processes ex. chemical factories by spillage of gas-generating chemicals and heavy hydrocarbons o 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.We can supply high performance membranes for resisting methane, radon and C02 for basements and structures. These are designed to protect buildings and their occupants from the effects of harmful gasses.