Residential

General

Radon is a naturally occurring radioactive gas that originates from the decay of uranium in rocks and soils. It is colourless, odourless and tasteless and can only be measured using special equipment. When radon surfaces in the open air, it is quickly diluted to harmless concentrations, but when it enters an enclosed space, such as a house or other building, it can sometimes accumulate to unacceptably high concentrations. Radon decays to form tiny radioactive particles, some of which remain suspended in the air. When inhaled into the lungs these particles give a radiation dose that may damage cells in the lung and eventually lead to lung cancer.

Scale of the Radon Problem in Ireland

On the basis of a nationwide survey of radon in domestic dwellings, the RPII have estimated that there are some 91,000 houses in Ireland with Radon concentrations in excess of 200 Becquerels per cubic metre. This is the reference level above which the government recommends that householders should consider carrying out remediation measures. The RPII is an independent public body under the aegis of the Department of Environment, Heritage and Local Government. The RPII was established in 1992 under the 1991 Radiological Protection Act, which conferred on the RPII a broad remit in relation to radiological protection in Ireland.

The RPII have produced a map showing higher Radon areas around the country.

Preventative Measures

Since July 1998, all new dwellings and long stay buildings are required to incorporate some degree of radon preventative measures at the time of construction in accordance with the revised Building Regulations. Inside buildings the air pressure tends to be lower than pressure levels outside. This is due to a combination of wind and temperature differences. The result is that radon soil gas and air are drawn into buildings through the many small gaps and cracks formed during, and after, construction, e.g. in solid floors and walls at ground level, through construction joints and around service pipes.

Radon is excluded from buildings using passive protection measures. Radon can also be removed using active protection. You should make provision for subfloor depressurisation by installing a radon sump/s and network of pipes during construction as highlighted in the Irish Building Regulations 1997- 2008 Technical Guidance Document C (Section 2).

Sub-floor depressurisation, also called sub-slab suction, is a most effective way of reducing radon levels should the need arise at any time over the lifecycle of a building. By installing a radon sump under a ground floor slab a void is provided from which radon can be drawn by use of an extractor fan; this lowers the sub-floor air pressure relative to that indoors. The radon gas is sucked from below the floor and vented by an external pipe to the air above the building. The radon is quickly diluted and will cause no further harm to health.

As radon levels are generally established when a building is completed and may alter over its lifecycle due to change of use e.g. the reduction of ventilation or the addition of extensions, the installation of a radon sump and pipework at construction stage is easy and inexpensive and a useful precaution even if never used.

Note: The radon sump and pipework do not provide any radon removal until a fan is fitted to an external vent pipe, and the system is activated.The Radon Sump provides the void under the ground floor slab from which radon soil gas can be extracted.A radon barrier effectively seals all three critical areas of ground-floors in buildings: - Walls, Floors & Penetrations (Service and Structural), thereby ensuring the necessary degree of separation between the interior spaces of a building and the underlying soil.

Radon Resisting Membranes can be used in most common floor constructions. They are installed in a similar way to damp proof membranes, but with much greater attention to detailing and workmanship. These radon resisting membranes will also perform the same function as damp proof membranes.

To be fully effective, radon resisting membranes must bridge cavities in walls and in doing so should form a cavity tray. Where necessary narrow strips of membrane can be used to seal walls and cavities. All designed cavities must be properly closed.

Avoid creating slip planes in masonry walls – do not set a damp proof course in contact with a barrier. Consideration must be given to the positioning of a radon resisting membrane in relation to thermal insulation. The integrity of a radon resisting membrane must be maintained during installation. Radon Resisting Membranes are resistant to puncturing and tearing, but where damage occurs this must be repaired by covering with a second layer of membrane sealed to the original using sealant tape. A surface blinding of soft sand (50mm min. thickness), or geotextile, should be used to prevent puncture of the membrane during installation. A further protection over the membrane is afforded by using high density insulation (25Kg/m3).

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