When is my house / my flat particularly in danger?

Is my house safe from radon?

If radon accumulates in indoor spaces, it can cause lung cancer. Whether a building is particularly susceptible to the accumulation of radon concentrations depends on various factors.

Insulation against moisture

Where a building lacks a continuous foundation slab, the insulation against moisture from the building plot often has weaknesses at the transitions between the foundation slab and walls in contact with soil or between different building parts. Radon can easily penetrate here from the building plot.

Buildings constructed before 1960 were usually built without a continuous foundation slab and used materials for moisture insulation that were not fused or glued and were often already defective. Radon can penetrate here too.

Location of the building

If a building is in an area where a high radon concentration is expected in many buildings, there is an above-average chance that concentrations of radon will occur in the building that are higher than the reference value stipulated in the Radiation Protection Act of 300 becquerel per cubic metre. This likelihood ranges from around 10% to over 50%.

Areas in which a high concentration of radon is to be expected in many buildings must be designated as radon precautionary areas by the federal states.

Where there are very high radon concentrations in the soil air, as can occur in these areas, radon can also penetrate (diffuse) extensively into buildings through sealing materials. In these areas, it is therefore not always a sufficient protection measure simply to seal the building against ground humidity.

Basements

Older buildings usually do not have a concrete cellar ceiling, and cellar doors often offer little resistance to air currents so radon-rich air from the cellar can easily penetrate the ground floor of the building.

Even small gaps in the cellar floor and cellar walls or an unsealed annular gap around a cable channel is enough to permit the entrance of radon-rich soil air.

Retrofitted or un-grouted stone vaults and bare, bricked or stone cellar floors provide only a slight barrier to radon-rich soil air penetrating from the subsoil.