Radon mitigation in basements
In radon-risk areas basements can be found to contain particularly high concentrations of radon. This is because radon gas is heavier than air and will therefore have a tendency to accumulate at the lowest level of a building.
In some cases, the basement tanking system will provide adequate protection against the ingress of radon. However, where a radon measurement reveals levels of radon above the recommended action level, remedial measures will usually be required. The BRE identify six main methods of reducing the amount of radon entering a house with a cellar or basement. 
- Installing a radon sump system
- Sealing floors and walls
- Increasing underfloor ventilation
- Installing whole house positive pressurisation or positive supply ventilation system
- Improving ventilation of the house
- Improving ventilation of the cellar or basement
Figure 1: Sump pump radon mitigation system
A simple way of combining the first three of these methods is to install a cavity drainage system such as Oldroyd Xv Clear connected to a modified sump system designed to pump both water and radon away from the basement. An example of such a radon mitigation system is shown in Figure 1.
 BR343 “Dwellings with cellars and basements: a BRE guide to radon remedial measures in existing dwellings” CR Scivyer and MPR Jaggs.