About the right ventilation


The user of the apartment can contribute by his behaviour to the fact that moulds do not find favourable growth conditions in the apartment. Correct ventilation and heating can limit the humidity in the building. The relative humidity of the air in the building should not exceed 65 – 70 % permanently.

To reduce the humidity in the room, a short shock ventilation (open one or more windows wide for 5-10 minutes) should be carried out several times a day. Cross ventilation is particularly effective. In individual cases, if, e.g. due to the absence of the room user, butt ventilation is not possible, gap ventilation can also make sense. In the case of newly constructed or renovated living space, significantly increased ventilation is required over a certain period of time as a consequence of the associated building moisture.
In rooms with high humidity and good thermal insulation, it is sometimes not possible to reduce the humidity to the necessary level by reasonable manual ventilation. In these cases, mechanical aeration and ventilation can provide a remedy.

In the bathroom

In the bathroom, especially in rooms with insufficient ventilation, the water should be removed from the walls and floor after showering. It no longer needs to be ventilated. After showering, the windows in the bathroom (if available) should be opened wide for a short time.
Since wet towels and walls in the bathroom, despite brief ventilation, can still contain a lot of water and thus too high a relative humidity in the room in the long term, it can be helpful to keep the doors to other heated rooms open after ventilation. For small windowless rooms, we also recommend installing mechanical ventilation, if possible controlled by humidity sensors.

In the kitchen

In the kitchen, much moisture can be removed from the room by means of an extractor hood with exhaust air discharge to the outside. This type of extractor also makes sense from the aspect of removing cooking fumes and combustion gases (when cooking with gas). Extractor hoods with recirculation are not suitable for reducing humidity in the kitchen.

Cool rooms

Less heated rooms (e.g. bedrooms) should not be warmed up with warm air from other rooms (in the evening). In colder rooms, condensation may otherwise be generated on walls or windows. If the bedroom is not heated enough, good ventilation should be provided for the removal of moisture (every sleeping person releases water vapour), otherwise condensation may form.
In rooms that have not been used and heated for a longer period of time, the following should be observed when used again
be ventilated more often beforehand.

In absence

If the windows of an apartment cannot be opened several times a day due to the absence of the inhabitants, at least the interior doors should be kept open so that moisture still present from the wetter areas (e.g. kitchen, bathroom) is evenly distributed over all rooms.

If you are concerned that there is a source of mould in your home that could affect your health, consult your local health authority or consumer protection agency.
If you already suffer from health problems that you fear may be related to mould growth in your home, please contact your family doctor, environmental medicine centres or the state medical association.

Who will inspect the apartments?

If you would like to know who in your area carries out house inspections and mould analyses, please consult your local health authority or a consumer protection centre.
When placing orders for mould measurements, make sure that the laboratories have an internal quality assurance system and regularly participate successfully in external quality assurance measures.

Mould growth in the interior is a hygienic problem that cannot be tolerated for precautionary reasons. If there is evidence of mould growth in the interior, professional remediation measures must be carried out to remove the moulds. However, the removal of mould infestation only makes sense if the causes are clarified beforehand. Without this clarification and the elimination of the causes that have led to growth, a new infestation is inevitable.


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