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Ground Gas

Ground Gas is a growing problem throughout the UK and is continuing to increase as more awareness, and a better understanding of its potential impact is being recognised by homeowners and professionals.

Some harmful gases occur naturally in the ground while others are the result of human activity such as dumping, landfilling and mining. These and other activities have caused pollution and created conditions where harmful gasses build up in the ground. High concentrations of harmful ground gas have the potential to create health risks to those living or working in buildings that are close to or on top of them.

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How does ground gas occur?

Ground gases either occur naturally or increasing through environmental pollution normally originating from human activity. This can be from:


  • Coal bearing strata
  • Bedrock and sediments containing Uranium
  • Calcareous rock (limestone)
  • Organic sediments (peat, alluvium)


  • Landfill
  • Made up ground
  • Mining
  • Past contaminative activity

What type of ground gases are there?

You might be surprised to learn, but there are many different types of ground gases. They include:

  • Radon
  • Carbon Dioxide
  • Carbon Monoxide
  • Nitrogen
  • Methane
  • Hydrogen Sulphide
  • Volatile organic compounds (VOC)

Property Problems - Ground Gas Protection - PCA

Why has ground gas become a problem?

If you have lived in your property for a considerable amount of time with no current ground gas protection, you may be wondering WHY you may be affected by the issue now. This is simply due to ground gases not being perceived as a risk in the past.

Equally, as the need for more new homes has grown, so too has the pressure to find sites to develop on. This has led to the increasing development on what is known as ‘Brownfield sites’ (previously developed sites) that often contain pollutants affecting the ground and soil.

With the combination of increased awareness and risk, it has led to the Environment Agency producing new legislation that has been adopted by local authorities leading to a much stricter approach when dealing with potential ground gas issues.

What is the potential impact of not doing anything?

The impact of not reacting to the potential of ground gases really depends on the type of ground gas discovered. For example, the effects of radon on the human body can cause health issues, while the impact of Methane and Volatile organic compounds (VOC) can be explosive/ flammable and the impact of Carbon Dioxide can be toxic.

Together with the implications to health and the risk of fire, homeowners may also find that the property is too much of a risk for mortgage lenders.

How can I protect against ground gas?

It is important to stress that ground gas protection is a highly specialised operation and we strongly advise that if you have a need to investigate and possibly protect against a potential ground gas issue, that you ensure it is undertaken by contractors who have the appropriate knowledge, experience, qualifications and skill levels.

While ground gas protection measures are ideally carried out at foundation level while a property is being built, for the large majority of homeowners already living within a property, foundation based ground gas protection will most likely be impractical.

With foundation based protection being unlikely or very difficult for existing homes, ventilation is the key. Through a combination of natural ventilation for suspended floors, improved underfloor ventilation and the introduction of mechanical ventilation measures; ground gases can be controlled and safely vented away from your home or property.

Where can I find a specialist ground gas contractor

In response to the growing problem of ground gas, leading industry specialists have come together to form the ‘Ground Gas Protection Group’ within the Property Care Association. This will allow homeowners to find appropriately qualified ground gas specialists. Any ground gas specialist on our register will be able to:

  • Analysis and produce a system design
  • Produce specifications
  • Conduct installation in accordance to ‘Codes of Practice’

To find a ground gas specialist, simply run a search using the tool below.

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