In the first instance, the building should be ventilated regularly – and in such a way that all the air in the entire internal space is exchanged within a few minutes.

Transverse ventilation accelerates air exchange. Transverse ventilation means opening windows on different sides of the building so that a draught is generated in the room that more quickly exchanges the stagnant air. The room loses less of its heating warmth through short, intensive ventilation.

A ventilation plan – ideally in combination with regular alarm calls or the calendar function on a mobile or computer – helps prevent regular ventilation from being forgotten.

As this measure is not always sufficient to sufficiently reduce the radon concentration in the building, its success should be tested by taking measurements.

If it is shown that manual ventilation can reduce the radon concentration sufficiently, it is sensible to build in a technical ventilation system (e.g. with heat recovery) as a permanent solution.

Sealing doors and cabling to the cellar is cost-effective and almost everyone can do this themselves.

Sealing water and heating pipework to cellar

Cracks, joints (for example at junctions with pipework) and small holes can be sealed with permanently elastic putties such as silicon, even if these demonstrate only a small amount of movement (e.g. because of temperature changes).

Experienced DIYers can seal these areas themselves if they work correctly and carefully.

Sealing doors to cellar

Moving components such as doors and their hinges can be sealed with elastic sealing profiles (lips and hollow chamber profiles). To do this, sealing profiles and hinges must be fitted to one another and the seal must be correctly adjusted. An all-round seal is sufficient.

Elastic seals lose their effectiveness over time and should be replaced periodically; at the very least, they should be checked every five to eight years. Because sealed doors are air-tight only when they are closed, it can be worthwhile installing an automatic door closer on more important junctions such as the cellar door.

The success of these measures in sufficiently reducing the radon concentration in the building should be tested by taking measurements.

Searching for the way by which radon gets into a building is very challenging.

If no obvious cracks in walls touching the soil or insufficient sealing of cabling leading into the house can be seen, experts should be called in. They can identify unsealed points in the cellar and know the best way to seal them.

The success of these measures to sufficiently reduce the radon concentration in the building should be tested by taking measurements.

An internationally tested remediation method is to suction radon-rich soil air from beside or beneath the building. However, this presumes sufficient gas permeability of the building plot.

The success of this measure to sufficiently reduce the radon concentration in the building should be tested by taking measurements.

Radon specialists provide information on measures to protect against radon. They help to maintain the proportionality of measures and effects to balance the expenditure and success potentials of various remediation options against one another.

TÜV Rheinland and Bau Bildung Sachsen offer advanced training courses on the subject of radon.

Fundamentally, Radiation Protection Act demands that when constructing a new building, measures must be taken in the inhabited rooms or workplaces to prevent or to significantly impair the entry of radon from the building plot.

According to Section 123 of the Radiation Protection Act (StrlSchG) (in German only), these measures should comply at the very least with the generally recognised technical regulations required for humidity protection. If a house is built in an area where a high radon concentration can be expected in buildings, additional structural measures are obligatory to protect it from radon. For new-builds, constructors have to implement additional structural measures to prevent as far as possible the penetration of radon into the building.

For example, a solid foundation slab made from watertight cement protects new buildings from ground humidity and therefore also against radon penetration. Radon protection films and radon-impermeable constructions offer additional effective sealing against the gas penetrating from the soil.