Raise pressure; positive pressure fans
Floor type: Above floor
Radon can be reduced by raising the air pressure within the living space of a property. This method is called positive pressurisation or positive input ventilation. Positive pressure fans are more effective where radon levels are below 500bq; over 500bq a sump system or under-floor ventilation system should also be considered, as these are likely to be more effective at higher radon levels.
Domestically, positive pressure fans are usually fitted in the loft, but can be fitted on a wall where there is no loft space, in flats for example. Positive pressure fans can be used with both solid and suspended floors. The only part of the fan that is seen is the outlet, which is similar to a bathroom light fitment in size and is made of plastic. Positive pressure fans are most effective where the property is well sealed and where windows usually remain closed. Positive pressure fans can control condensation as well as radon, and so are a good choice for properties with damp and radon issues.
See also BRE quick guide 3 for more information