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REMEDIATION OF EXISTING BUILDINGS – REMEDIATION CAN SAVE YOUR LIFE AND YOUR MONEY

Remediating a building has a beneficial effect on the health of its occupants, because the risk of lung cancer decreases by 15 % for each 100 Bq/m³ reduction in the radon concentration in a house. If the indoor radon concentration is lower than 600 Bq/m³, the remediation is based on sealing significant radon entry routes from the soil into the building, especially cracks in the building substructure, service pipe entries and inspection chambers, by preventing air movement from the cellar to the first floor, etc. If the indoor radon concentration is higher than 600 Bq/m³, it is necessary to install sub-slab ventilation. Forced sub-slab ventilation decreases the air pressure beneath the building and thus eliminates radon transport into the building. This is nowadays considered the most effective remedial measure (Fig. 1). Flexible perforated pipes placed in a sub-floor layer of coarse gravel (Fig. 2) are usually used for soil air suction. This procedure requires new floors. Another option is to suck the soil air from perforated tubes drilled into the sub-floor layer from the cellar (Fig. 3), from a floor pit excavated in one room (Fig. 4), or from an external trench (Fig. 5) without damaging the existing floors. The fan is usually installed at the top of a vertical exhaust pipe or in a suitable place in the garden.


Fig. 1 - The average efficiencies of different radon remedial measures installed in existing buildings.


Fig. 2 - Flexible perforated pipes inserted in a sub-floor layer of coarse gravel placed under the new floors.


Fig. 3 - Perforated tubes drilled into the sub-floor region from the cellar and ventilated above the roof.


Fig. 4 - Perforated tubes drilled into the sub-floor region from the floor pit and ventilated above the roof.


Fig, 5 - Perforated tubes drilled into the sub-floor region from the external trench .