Using pressure extension tests to improve radon protection of UK housing.

In order to demonstrate conformity with the current Building Regulations, many house builders are incorporating sumps beneath the ground floor construction of houses within the designated Radon Affected Areas. These sumps will allow for later depressurisation of the below ground floor construction and thereby prevent radon passage to the internal building environment. There are concerns regarding the costs of these measures and also the potential for these sumps to be used by vermin as nesting sites as well as their effectiveness. This paper reports on an ongoing study into the effect of different fill materials on sub- slab depressurization. In each test suction is applied at the centre of a floor slab and the resulting pressure field and flow rate is measured. These data give a good indication of the way in which a sump would be expected to perform. The results show that there is significant variation from fill materials described as being the same.