ProTen Services feature in Housebuilder & Developer magazine

If in Doubt, Don't Build Without

Martin Freeman, Managing Director of specialist contractor ProTen Services Ltd, explains the dangers of radon gas and recommends the ‘best practice' for installing radon protection in new buildings.

Click here to view the article in PDF format as it appeared in Housebuilder & Developer

Radon is a naturally occurring radioactive gas, formed during the decay of uranium in the ground. When it surfaces into open air it is quickly diluted to a harmless concentration, however if it enters a building, it can build to potentially dangerous levels. Statistics reveal there are approximately 2500 deaths in the UK every year from lung cancer, linked directly to exposure to high concentrations of the radioactive gas.

Radon is found in all parts of the country, but buildings in certain areas are more likely to contain high levels of the gas than others, due to the underlying geology. Protection can be installed at the time of construction that should prevent the gas from infiltrating into the property. Measures can also be taken to provide a ‘back-up' remedial solution that can be activated, should the building later develop a radon problem.

Section C1 [Resistance to Contaminants] of Schedule 1 of the Building Regulations 2000 states that "Reasonable precautions shall be taken to avoid danger to health and safety caused by contaminants on or in the ground covered, or to be covered, by the building and any land associated with the building".

Further guidance is given in Approved Document C (2004 edition), where section 2.39 explains that "To reduce the risk [to occupants of developing lung cancer] all new buildings, extensions and conversions, whether residential or non-domestic, built in areas where there may be elevated radon emissions, may need to incorporate precautions against radon". Section 2.40 continues to inform that "guidance on the areas susceptible to radon" can be found in BRE Report 211 (revised 2007).

These Regulations leave themselves open to individual interpretation, and unfortunately do not appear to provide a definitive ruling as to whether a new building in any given area must have radon protection installed. Given the potentially serious consequences to occupants of a building that is not protected from radon, however, it is advisable that all specifiers and developers err on the side of caution.

Although BRE Report 211 was revised in 2007, a printed map has limitations as to the level of detail that can be provided for a given area. The Health Protection Agency and the British Geological Survey have recently launched a website, http://www.ukradon.org/, which allows visitors to input a postcode to obtain an estimate of the radon level for a specific property or piece of land. The website is constantly updated to give visitors the most up-to-date and accurate information, which may not be the case from a printed map. It should always be remembered, however, that any such data is based upon estimates and data extrapolation, and so a property could be affected by radon even when the maps and dataset indicate otherwise.

A radon membrane laid across the footprint of a building provides basic protection from the gas, and the difference in cost between this, which combines as a DPM and vapour barrier, and a basic DPM is negligible; the additional cost for most buildings will be relatively marginal.

It is recommended that a radon barrier be fitted in any new development that lies in a government designated radon Affected Area. As far as practicable, membrane joints should be heat welded, rather than taped, to minimise the risk of leakage. Pre-formed collars or ‘top-hats' should be used around service inlets.

In any area where the HPA has predicted that more than 3% of homes will contain a high level of radon (thus indicating a more widespread occurrence of the gas and an increased likelihood of exceptionally high concentrations being found), it would be wise for provisions for future remedial work to be made, in addition to the installation of a radon membrane. This simply involves the creation of a sump under the building's foundations, complete with an extract pipe that leads out of the property. The location of the pipe should be marked, so it can be accessed and the sump can be activated with a fan should it become necessary.

It is important to note that radon protection is a specialist area of work, and should therefore only be carried out by trained professionals. A recent study (Denman et al, 2005) found a staggering 60% of radon membranes installed in new properties had failed to prevent the gas from entering the building. Whilst this was a relatively small study, it is nevertheless indicative of serious failure. Over the past 10 years it has become accepted that below-ground waterproofing is a specialist area. The history provides a good parallel with radon protection, where effective design, quality of materials and standard of specialist workmanship are paramount.

A crucial aspect of radon protection in new buildings is the need to carry out post-construction testing, to confirm that measures have been effective. This, coupled with a visual inspection of the barrier after it has been laid, will allow the work to be confidently signed off.

The mantra ‘to test is best' is often applied to existing buildings with regards to radon, however for radon protection in new buildings, the best advice is ‘if in doubt, don't build without'.