A recent study has revealed that more than three-quarters of Britons with home extensions are unaware of the potential risks they may face from long-term radon gas exposure*.

The British Standard ‘code of practice’ when waterproofing below ground states that radon must be considered in the design. The code has been in place since 2009, and homeowners should have been made aware of the risks associated with radon if they completed a project that required excavation, such as a basement conversion, during this time. However, not all tradesmen have shared the information, and homeowners have been left in potential danger.

What Is Radon Gas?

Radon is a naturally occurring radioactive gas found underground. It can enter properties when the gas is released from the ground, through building work such as excavating. As air pressure inside buildings is lower than outside, once released the gas is drawn up into the property.

Radon is colourless and odourless, formed by the breakdown of small amounts of uranium naturally occurring in all rocks and soils. It exists everywhere in low doses, but in some places levels can be higher, which is where harm can be caused.

Radon is measured in becquerels per cubic metres of air (Bq m-3). According to Public Health England, the average level in UK homes is 20 Bq m-3, while your risk is low if levels remain below 100 Bq m-3. However, as the levels of radon gas rise, so does the potential risk. At 200 Bq m-3, there is a real cause for concern.

The Dangers of Radon

Long term exposure to radon gas, caused by living in a property where the gas is being released, can lead to lung cancer. Radon gas is responsible for 2,000 fatal cases in the UK every year, making it a very real danger. Lung cancer is a specific concern due to breathing in the ‘decaying’ gas, which continues to emit radiation once inhaled. This risk is greater for smokers.

Radon gas is the second leading cause of lung cancer in the UK, but many homeowners completing projects like basement conversions, or extensions and conversions that involve excavation, are not aware of the dangers caused by releasing radon gas.

Martin Freeman, MD of propertECO.co.uk:

“Properties with basements are at increased risk, so it is very important that when new basements are being created, radon is taken into consideration to ensure a safe environment for the occupants. The only way to know if a building is affected is to carry out a radon test using a special detector upon occupation. Basements can provide valuable extra living space and are an excellent way of extending a home, however they must be created in a way that ensures they are safe to occupy.”

Testing For Exposure

The UK Radon Map can be downloaded from ukradon.org, showing areas in the UK which are most at risk for high levels of the gas. However, it is important to note that every building contains radon however the levels of it are usually low.

Radon can only be detected using a special radon test. Testing kits are available from PropertECO from £33, offering a simple way of keeping yourself safe without having to call out a professional. The results are then sent off and analysed in an independent laboratory. If radon is detected, measures can be put in place to ensure your extension or conversion remains safe for use.

Preventing Radon Exposure

There are two main mitigation systems to combat radon exposure: a radon sump and positive pressure systems.

Radon sump: A void below the building is created as the lowest point of pressure, drawing gas from the soil into the space. The gas is then safely vented away from the property, using an exhaust pipe with a built-in fan. Sump systems are also used in new build properties in radon affected areas. This method is ideal for high concentrations of the gas.

Positive pressure systems: A specialised fan located in the attic or on the internal side of an external wall draws clean air into the property to pressurise the building. This pressure change stops the radon from being drawn into the house from the soil, by making the pressure in the house higher than the surrounding area.

Retrofit Options

If you’ve already completed a building project but are concerned about radon exposure, it is better to be safe than sorry. If your property was not tested during the works, pick up a radon test and check to be sure.

If the test shows high levels of radon in your property, there are some things you can do:

  • Contact a specialist. UK Radon Association has a list of contractors who are experienced in dealing with radon in basements on their website, radonassociation.co.uk
  • Retrofit systems can be installed to successfully reduce radon levels. However, it is much easier and cheaper to install protection at the time of conversion, hence the importance of the original design taking radon into account.
  • Check the designs and plans for the works that were carried out and see whether radon was noted. If the works were carried out from 2009 onwards, you may have recourse against the contractor(s) involved.

If you are planning to renovate your home, and it involves digging down, ensure you have a plan in place should your project fall in a radon-affected area and make sure you talk through any concerns with your architect or designer.

*Survey by propertECO.co.uk, leading centre of expertise in radon gas control. Poll of 2,943 UK homeowners aged 25 and over

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