How to protect below-ground structures from a silent killer: Radon

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Alex Burman

What is Radon?

Once dubbed as the ‘invisible gas that’s a bigger killer than carbon monoxide’ which causes 1,100 deaths a year in the UK*, Radon is a colourless, odourless radioactive gas which is generated from the Uranium in all rocks and soil.

Radon concentration is at its lowest during the summer months and peaks to the highest levels between December and February and, whilst it is most prevalent in the South West of England, Radon is found everywhere across the UK.

The radioactive elements formed by the decay of radon can be inhaled and enter our lungs and, in severe cases, can cause lung cancer.

Compared with other causes of premature deaths in the UK, lung cancer from Radon at home kills more people per year than drink driving**.

However, there’s no need to panic; with the correct waterproofing and gas-protection measures, the risk from Radon ground gas can be all but removed.

Current legislation

The BRE Report BR211 (2015) Radon: Protective measures for new buildings applies to all new buildings, extensions, conversions and refurbishment for domestic and non-domestic use.

It explores the routes by which Radon can enter a dwelling and advises on the two methods for achieved protection: passive and active.

Minimum protection requirements are a 300 micro PE membrane (1200 gauge), however, as some diffusion will occur through the sheet because most radon entry is through cracks, taped laps are essential for extra protection.

The Sika solution


Sika® Bentoshield® Max LM is a self-healing waterproofing membrane that is resistant to contaminated soils. It forms an automatic mechanical bond to freshly-poured concrete and comprises two polypropylene geotextiles, one woven and one non-woven encapsulating a layer of granular sodium bentonite.

With a 0.3mm laminate (300 micron) it is fully compliant with BR211 and can be used for Radon protection and waterproofing.

Suitable for areas subject to changing geological conditions, such as flood plains, areas of soil settlement and brownfield land, Sika® BentoShield® Max LM is easy to install, with no primers or protection boards required.

Thanks to its ability to be applied in temperatures below 0°C and also of high humidity, major constructions benefit from the speed at which the product can be installed.

Sika® BentoShield® Max LM is just one in Sika’s extensive range of waterproofing and gas protection products along with SikaProof and Sikaplan Gas Barriers.

To find out more about how to protect a building from Radon, contact Sika Limited on 01707 358570 or email




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