Ground Gas Barrier Membranes

A gas barrier membrane is a critical component in foundation construction, designed to prevent harmful gases such as radon, methane, and volatile organic compounds (VOCs) from infiltrating buildings. These gases can pose significant health risks to occupants if allowed to accumulate indoors. The membrane forms an impermeable seal over the foundation and is typically installed in conjunction with a high-permeability ventilation layer to facilitate the safe dispersion of gases.

To be effective, the membrane must be continuous and properly sealed at all joints, service penetrations, and terminations. Overlapping sections should be securely bonded using appropriate tapes or sealants to prevent leaks. Additionally, compatibility with other foundation components, such as damp-proof membranes, is essential to avoid compromising either function.

In some cases, multi-layered or reinforced membranes may be used for added durability, particularly in areas with high concentrations of hazardous gases. Proper installation is key, requiring careful handling to prevent punctures or tears that could reduce effectiveness.

Regulatory requirements and building codes often dictate the type and specification of gas membranes depending on site conditions. Conducting a thorough site risk assessment will help determine the most appropriate system, ensuring long-term protection for the building and its occupants.

Radon comes from the decay of uranium in rocks and soil. Commonly found over granite formations, it’s a colourless, odourless and radioactive gas. Extended exposure to radon can be harmful. When you breathe in radon gas, it goes into your lungs and exposes you to small amounts of radiation. This may damage the cells in the lining of the lungs and increase the risk of lung cancer. Current figures estimate that 1000 deaths a year in the UK can be attributed to lung cancer caused by radon. The risk is higher in those who have lived or worked for many years in a radon-contaminated building. Buildings that occupy land containing certain levels of radon are prone to contamination. The radon level in the air we breathe outside is very low but can be higher inside buildings.

In many cases, radon levels aren’t an issue, but Building Regulations require all new buildings and extensions/conversions to undergo protective measures to ensure they are adequately shielded from radon.

Where in the UK is radon concentrated?

The most prominent areas to find high levels of radon gas are in Wales and the South West of England. There are also concentrated areas in some parts of the North West England, North East England and the Midlands. However, radon can occur in any region of the UK.

The only way to know if a building has a high radon level is to have it tested. If you live or work in a radon affected area, we recommend that a test is arranged. If you plan to build a development in a radon affected area, we recommend that you test the site to determine whether any protective solutions are required as part of your construction scheme.

Special consideration should be given to sites contaminated by Hydrocarbons or VOCs. These are very mobile compounds and will migrate relatively easily through unsuitable membrane materials. Aluminium laminates are superb gas barriers but these materials will delaminate when exposed to hydrocarbon vapour/VOCs. Furthermore, the aluminium layer is susceptible to oxidation due to moisture penetrating the exposed edges. A comprehensive range of task-specific engineered barriers and accompanying Accessories provide consultants and design engineers effective barrier solutions and for the contractor a rapid, simple and cost- effective installation.

VOCs, hydrocarbon vapours and other toxins are found on many brownfield sites, especially land previously occupied by chemical and paint works, timber treatment, petrochemical plants and fuel stores, petrol stations, tanneries, paint factories, paper mills, coalfields, disposal and landfill sites. Some naturally occurring gases are also harmful and these include radon, methane and carbon dioxide.

HDPE and other homogenous membranes, many of which claim to be hydrocarbon resistant, are in fact quite permeable to certain toxic vapours and gases and do not offer adequate protection.