Radon protection above ground
The BRE guidance document, BR211 describes two levels of radon protection: basic radon protection and full radon protection. The level of protection required is shown on the maps that accompany BR211. Plots located in light grey areas require basic radon protection and plots located in dark grey areas require full radon protection. However it is sometimes possible to adopt a lower level of radon protection than that indicated by the map if a BR211 radon report for the plot is purchased from the British Geological Survey at http://shop.bgs.ac.uk/GeoReports/.
Basic Radon Protection
To prevent radon from entering the building through the cavity, Oldroyd Xs will need to be linked to a cavity tray
Basic radon protection can be achieved by installing a damp-proof membrane that is also capable of resisting radon across the ground floor of the building. Oldroyd Xs is an ideal membrane for this purpose as it is tough enough to withstand damage on site and can easily be folded round details such as door-frames.
When using Oldroyd Xs to protect against radon, all joints should be double-sealed as shown below:
Full Radon Protection
Full radon protection acknowledges the fact that it is not reasonable to expect basic radon protection (above) to be installed perfectly, so the possibility will always remain for radon to pass through minor imperfections in the membrane system (e.g. where seals have not been perfectly formed). In order to get around this problem, full radon protection requires the addition of “active protection” in the form of a ventilated sump or floor void below the radon-proof membrane. This ensures that a high proportion of radon is expelled from the building before it comes into contact with the radon-proof membrane.
A simple and effective method of achieving full radon protection is to use a studded membrane such as Oldroyd Xv Black or Oldroyd Xv 20. This provides a radon-proof barrier whilst also forming a void that can be ventilated.