Table 3.

Comparing effectiveness of different construction solutions to avoid indoor radon in new houses.

Systems	Methods	Effectiveness
Barrier Membrane
Barrier membrane installed in 64 new houses during construction in Northamptonshire, UK (Groves-Kirkby et al., 2006) with barrier membrane. Compared the results with a study of post-construction remediation (Denman et al., 2002).	Radon levels measured in the main bedroom and living areas for three month using track-etch detectors.	The mean annual radon level went below the action level (200 Bq/m3) in ​40% of the new houses. ​Whereas the post-construction remediation found over 75% of houses below the action level.
With or Without Barrier Membrane and additional Block and Beam Protection
Construction solutions for three different group of houses were: a) Protected floor with barrier membrane and walls with cavity tray and compared with b) unprotected floor (no membrane) and c) protected with additional block and beam floor (Scivyer, 2001)	Radon levels measured in a) 131 protected houses and compared with b) 245 unprotected ones' and c) another 89 protected with additional block and beam constructed from 1990 to 1994.	a) 96% protected houses found below the action level compared to b) 80% unprotected houses c) almost all houses protected with added block and beam floor remained below the action level. This supported previous UK study conducted by Woolliscroft et al. (1994).
Radon piping installed under the floor slab of new houses
Finland requires radon preventive measures as a condition of construction permit (Valmari et al., 2014).	Radon piping installed under the floor slab that can later be activated if radon level goes over action level (400 Bq/m3)	Maximum 45% effectiveness noted in in new houses compared to 24% in old houses after activation of the radon piping.