Many homes have a suspended ground floor with a space underneath. Good ventilation of this space can reduce indoor radon concentrations.

There are two types of suspended floors:

  • Timber: floorboards or chipboard supported on wooden joists
  • Concrete: blocks supported on concrete beams is more common in modern homes


  • To identify a suspended timber floor, look outside for ventilation grilles just above ground level.
  • If there are not any vents outside it may be a solid floor. See our fact sheet: Radon sumps
  • Sometimes the vent leads only to the wall cavity and not to the under-floor space.


  • Consider using a 110mm core drill to break through the wall.
  • In some cases you may need periscopic ventilators.

The typical cost is £200, but might be up to £600. The materials needed are widely available in DIY stores.





How to reduce radon levels overview


Disclaimer. It should be noted that the measures described on this sheet are not guaranteed to reduce the radon level in your home, however similar measures have been proven successful in many UK homes.