General renovations offer a good opportunity to reduce indoor radon concentrations cost-effectively. It is therefore particularly important to carry out a radon measurement before a general refurbishment.

In the event of an increased radon concentration, plan radon protection measures in accordance with ÖNORM S 5280 Radon - Part 2: Structural precautions for buildings.

Thermal renovations change the tightness of the building envelope (for example by installing tight windows and external doors or vapor barriers in the roof area). This changes the pressure conditions and the air exchange rate and thus influences the radon ingress rate.

It is important to consider possible effects on the future radon situation in the building as early as the planning phase.

If the thermal insulation on the façade is not installed correctly, soil air containing radon can rise through cavities between the insulation and the wall. Leaks in the building envelope can allow radon to enter living spaces. These effects can lead to a significant increase in indoor radon concentrations.

In consultation with construction companies and specialists for structural radon protection, the following instructions should be observed during remediation:

• Radon protection measures can usually be implemented cost-effectively in the course of renovation work on floors or walls (especially in rooms in contact with the ground). Preventive measures are usually more effective and less expensive than retrospective measures. Further information can be found under Remediation measures for existing buildings.
• The rise of radon-containing soil air via cavities between the insulation and the outer wall must be prevented. This also applies to the penetration of soil gas into the interior of the building via leaks in the walls.
• Preventing the flow of air from the cellar into the living spaces by sealing has a positive effect on both the heat balance and radon protection. This can be achieved, for example, by sealing doors between the cellar and the living space.
• The installation of controlled ventilation is a beneficial measure with regard to radon. It must be ensured that only low-radon air is supplied and that no negative pressure is created in the building.
• If a single combustion system (e.g. tiled stove, kitchen stove or fireplace) is installed, ensure that there is a sufficient supply of outside air. A direct outside air supply is preferable.