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SUB-SLAB DEPRESSURIZATION SYSTEMS: EFFECTIVENESS AND SOIL PERMEABILITY

Martin Jiránek 1 , Mat ì j Neznal 2 , Martin Neznal 2
1 Czech Technical University, Faculty of Civil Engineering,
Thákurova 7, 166 29 Praha 6, Czech Republic 2 RADON v.o.s. corp., Novákových 6,
180 00 Praha 8, Czech Republic

Sub-slab depressurization (SSD) systems in the form of radon sumps are being considered as the
most effective and the cheapest radon remedial measures for existing buildings. Detailed
measurements were made in 17 family houses that had been remediated using this system.
Measurements results indicate that the performance of SSD systems depends substantially on the
soil permeability and on the presence or absence of a drainage layer beneath the floors. In case of
unpermeable soils without the drainage layer the effectiveness of SSD systems decreases, even if
they are ventilated by continuously operating fans. On the other hand, an intermittent operation of
fans is usually sufficient, when SSD systems are designed for houses built on permeable soils.