General renovations offer a good opportunity to reduce indoor radon concentrations at low cost. Therefore, it is particularly important to carry out a radon measurement before a general renovation.

In case of an increased radon concentration, plan radon protection measures according to ÖNORM S 5280-2 "Radon - Structural precautionary measures for buildings".

Thermal renovations change the tightness of the building envelope (for example, by installing tight windows and exterior 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 during the planning phase.

If the thermal insulation on the facade is not done properly, radon-containing soil air can rise via cavities between the insulation and the wall. Radon can enter living spaces via leaks in the building envelope. These effects can lead to a significant increase in indoor radon concentrations.

In coordination with construction companies and experts for structural radon protection, the following instructions should be observed during renovation:

• Radon protection measures can usually be implemented cost-effectively in the course of remodeling work on floors or walls (especially of occupied rooms in contact with the ground). Preventive measures are usually more effective and less expensive than retroactive measures. For more information, see Remediation Measures for Existing Buildings.
• Radon-containing soil air must be prevented from rising through cavities between the insulation and the exterior wall. This also applies to the penetration of soil air into the interior of the building via leaks in the walls.
• Stopping the flow of air from the basement into the living spaces by sealing has a positive effect on both heat balance and radon protection. This can be achieved, for example, by tight doors between the basement and the living space.
• The installation of controlled living space ventilation is a beneficial measure with regard to radon. It must be ensured that only air with a low radon content is supplied and it must be regularly checked that no negative pressure is created in the building.
• If a single combustion system is installed (for example, a tiled stove, kitchen range or fireplace), care must be taken to ensure that there is an adequate supply of outside air. A direct supply of outside air is preferable.