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Radon Barriers


Radon


Radon is a naturally occurring radioactive gas that enters buildings from the underlying soil and in certain cases can accumulate in a building to such a concentration that it is deemed to constitute a potential health hazard. Radon is deemed to be a risk factor for lung cancer.


It is not possible to accurately predict the concentration of indoor Radon likely to occur
in a proposed building on the basis of a pre-construction site investigation. Radon is measured in units of Becquerals per cubic metre. (Bq/m3). The National Reference Level (NRL) for Radon in dwellings is 200 Bq/m3 and The Radiological Protection Institute of Ireland (RPII) recommends that remedial works be undertaken where this figure is exceeded.


To obtain more information on Radon in the home please click here .

 

Reducing The Risk of Radon

 

Measures can be taken during the design and construction of a building, which will significantly reduce the risk of radon concentrations in excess of the NRL.


Dwellings in
High Radon Areas: measures should be taken to protect the building from Radon in the ground. For example, in the case of a noncomplex building of normal design and construction, a fully sealed membrane of low permeability over the entire footprint of the building and a potential means of extracting Radon from the substructure such as a standby Radon sump or sumps with connecting pipework or other appropriate certified systems should be provided.


Dwellings in Areas other than High Radon Areas:
the building should be provided with a potential means of extracting Radon from the substructure should that prove necessary after construction. For example, in the case of a non-complex building of normal design and construction, the provision of a standby Radon sump or sumps with connecting pipework or other appropriate certified systems should be adequate.


Membranes
used for Radon protection should be appropriate for this use and have independent certification from an approved body e.g. by the National Standards Authority of Ireland (NSAI) Irish Agrement Board (IAB).
www.nsai.ie The parameters certified should include those in Table 3. of the Building Regulations Technical Guidence Documents TGD Part C.


Table 3 identifies parameters, tests and minimum performance levels for Low Density Polyethylene (LDPE) membranes. Tests may vary for non-LDPE materials, however performance levels to be achieved should be equivalent to those identified for LDPE in Table 3. Membranes used for Radon protection will normally be provided in lieu of the damp-proof membranes described in Section 3 of this document.

 

The pipework from standby Radon sumps, should terminate and be capped either above ground level externally, or in the attic space. Externally, pipes should be provided with sealed caps - to prevent ingress of rainwater or rodents.


Pipe terminals should be clearly marked
to indicate the function of the pipework system to facilitate later activation should this prove necessary and also prevent misuse. For example, a marker plate may be erected on a permanent structure adjacent to the pipe terminal, or a pipe cap incorporating raised lettering may be used. By extending the pipework and installing and activating a fan, the standby Radon sump system becomes a sub floor gas extraction system. The terminal should be located so that the pipework and fan can be practically fitted, without causing unnecessary obstruction.

 

Installing the Membranes, Sumps and Associated Pipework

 

Particular care should be taken when installing the membrane. All joints and service penetrations must be fully sealed. In view of the difficulty of achieving gas-tight seals under site conditions, it is recommended that the membrane be prefabricated and installed by appropriately trained personnel.


Every precaution must be taken to protect the membrane
from damage, pre- and post- installation and also during its lifetime including making appropriate allowances for differential settlement.


Advice on design, location, and number of
standby Radon sumps along with design of associated pipework is contained in “Radon in Existing Buildings – Corrective Options” (2002).?
A single sump is likely to have influence over an area of at least 250m2 and for a distance of at least 15m from the sump. The hardcore layer should be clean, dry, will-compacted and gas permeable following the compaction process. Obstructions below the floor slab may reduce the effectiveness of the standby Radon sump system when activated. Accordingly, it may be necessary to provide perforations in the rising walls or separate standby Radon sumps with interconnecting pipework in each compartment.


The installation of measures in accordance with this guidance is NOT a warranty that Radon concentration levels will be reduced below the relevant National Reference Level. Building owners are recommended to have the Radon concentration level assessed when the building is in use and again after remediation action, should such prove necessary.


Information on the procedure to assess Radon concentration levels in occupied dwellings or workplaces can be obtained from the RPII or from other Radon measurement service providers. For Radon surveys in workplaces refer to RPII’s publication “Planning Radon Surveys in Workplaces – Guidance Notes” (May 2004).


The radon sump and associated piping and fittings should be installed in the hardcore filling. The sump should be within 15m of all of the external walls. In some cases one sump may not be sufficient and additional sumps may be required.

 

What You Will Need to do, look out for, and the Cost

Appoint your Radon Installation Subcontractor.  The radon membrane must carry an independent certification from an approved body such as the National Standards Authority of Ireland (NSAI) or the Irish Agrement Board (IAB) and should be laid with joints sealed.


Ensure the blinded hardcore filling has been fully compacted and is free of sharp projections which may puncture the radon barrier.


Ensure the radon sump and associated piping and fittings are installed in the hardcore filling. All pipe joints and where it passes through the wall should be sealed to prevent drawing-in air from the outside.


Ensure that there are no punctures, the joints are sealed with an appropriate tape, that the edges have been turned up and laid across the internal and external rising walls and proprietary top hat seals are used around service pipe penetrations.  


Your Radon Barrier Installation Subcontractor should provide all of the materials etc. necessary to complete this section of the works.  The Cost to supply and fit the radon barrier will be in the region of € 7.00 - € 8.00/m2 + VAT.  In addition to the Radon Barrrier, accessories such as a sump, terminal box and pipework will be required, which would cost in the region of € 80.00/dwelling Supply and fit.


Get detailed costs for this section of your project here

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