Property Searches – Radon Risk


Property Searches – Radon Risk

Radon is an odourless, colourless radioactive gas that is formed by the decay of naturally occurring elements in soil and rocks. It may also be present in water and certain building materials. If you have never heard of this gas, it will surprise you to learn that it is the single biggest source of radiation exposure in the UK population in homes and workplaces. It is present in air both indoors and outdoors and is the second biggest cause of lung cancer after smoking. However, in better news, there is currently no strong evidence to link exposure to it to any other cancers or other disease.

Where is radon found?

All rocks and soil produce radon to some degree. The British Geological Survey (BGS) found that areas of England, particularly Cornwall, Devon, Somerset, Derbyshire and Northamptonshire, East and West Scotland, and Southwest Northern Ireland, are all affected.

Radon in housing standards

Each part of the UK have their own regulations, guidance and supporting material that aim to make sure that homes are of an adequate standard. This is because the gas varies in concentration across the UK. England and Wales use the Housing Health and Safety Rating System (HHSRS), which identifies radon as a potential health hazard under the Housing Act 2004. In Scotland, a review in 2018 of housing standards include radon as a subject that may be included in an updated standard for tolerable housing. The situation in Northern Ireland is they have started a consultation, including proposed adoption of the HHSRS. At the time of writing, neither Scotland nor Northern Ireland have concluded their consultations.

Radon from building materials

Some building materials contain modest amounts of an element called Thorium and also radon, which can emit thoron and radon into the air. Private water supplies may also be a source of radon indoors.

Building materials with high thorium content may leak thoron into buildings in which they have been built. The UK national radon survey, last carried out in 1988, found that radon from building materials typically leads to low exposure and has not been found in such concentrated form as to trigger the UK Action Level.

Radon in water

Water from underground sources that have been found to have high levels of uranium or radium and may have concentrated levels of dissolved radon. In some private domestic groundwater drinking supplies, exposure can occur via inhaling the gas in indoor air when water is drawn through taps, or showers, for example, and to a lesser degree from the ingestion of radon in water.

Measuring radon in homes

There are many organisations able to carry out measurements of the gas in homes. Long-term domestic measurements are made using two detectors, one placed in the main living room and the other in an occupied bedroom for a period of at least 3 months. This helps to even out short-term fluctuations. These detectors can be sent to you by post, as they are about the size of a digestive biscuit. After 3 months have elapsed, you post them back and your home’s radon level is calculated.

The results are combined to reflect general domestic occupancy and corrected for seasonal variations in radon levels and are then compared with the Action Level and Target Level to guide decisions about installation of radon remediation.

Shorter-term measurements using passive detectors may also be put in place, alongside electronic, or active, monitors. These measurements can be used to provide an indication of radon levels and are often used as screening measurements.

Reducing radon levels in homes

If high levels of the gas are found in your home, there are practical remediation methods available to reduce its concentration. Homeowners are advised to reduce radon levels above Action Level and to give serious consideration to reducing levels between Target and Action Levels, taking into account the greater risk to current smokers and ex-smokers.

Reducing the risks

Ideally, preventing the gas from ever entering a home in the first place is the best solution. High radon levels in homes are caused by the flow of air containing the gas coming through cracks and gaps in floors. The flow is driven by air pressure differences between the underlying ground and the house.

Remedial measures can be taken to prevent the gas from entering the home. These include:

  • Eliminating or reducing the difference in pressure between gas in the soil and gas in the home
  • Sealing the floor of the house
  • Removing radon once it has entered a house

Methods for reducing radon levels in the home

  •  Underfloor extraction or radon sump system

A sump is a small space, about the size of a bucket, into which the gas can be collected before being vented into the open air. The sump is channelled under a solid floor from the side of a property and attached to a pipe and fan. For a conventional house, this is often the most effective method.

  • Improved ventilation under suspended timber floors

New air bricks are installed in the home’s wall to ventilate the space underfloor. In some cases, a fan is added. This works by decreasing the amount of the gas entering the living area of the home.

  • Positive ventilation

This blows air into the living space from the loft, diluting radon and reducing leakage into the house by slightly increasing the air pressure.

  • Sealing gaps and cracks in solid concrete floors

The seals prevent the gas from entering the home through the floor. However, it is vital that all cracks and gaps are sealed for this method to be effective. Sealing only 90% of the cracks, for example, is likely to have little effect on radon levels. The work involves removing carpets and skirting boards in all downstairs rooms, which can be extremely disruptive.

  • Additional permanent ventilation

This is the least effective way to reduce radon levels in the home, but it can work if levels are at the lower end. It includes the installation of trickle vents in windows and lockable catches that hold windows permanently open. It should not be possible to close the windows or vents fully once they have been installed.

How much does it cost?

The method of remediation will be dictated by the radon level, the size of the property, and its layout. However, other factors, such as the resident’s lifestyle and existing ventilation or air conditioning systems, can play a role too.

Once the most appropriate level has been identified, other factors may affect the cost of installing a radon mitigation system, including:

  • Size of the property
  • Layout and history of property
  • Building materials
  • Aesthetic considerations
  • Electrical connections
  • The equipment required

Taking all the above factors into account, the cost of a professionally installed radon remediation system will generally range from £1,000 to £4,000 for residential properties. Although there will be circumstances where many additional factors can result in costs being outside this range.

Effect on the housing market

Buying and selling property is based on the principle of caveat emptor – buyer beware. As part of the conveyancing process, potential buyers solicitors carry out a local authority search which contains standard questions about drainage, planning and highways. Additional questions might be asked if the circumstances warrant it, and radon is included here. If concerned, potential buyers have to specifically enquire about radon, and consult reference maps produced by the National Radiological Protection Board (NRPB), BGS and others. However, because remediation works can be carried out on properties in areas with high radon levels, it should not be a bar to housing transactions.


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