Short Answer
Failing to perform structural shock ventilation daily constitutes a direct breach of your statutory tenant duty of care regarding property maintenance.
German apartments are built to be highly airtight, meaning regular air exchange is a strict requirement to prevent moisture damage and mold growth.
What Most Expats Don't Realize
You kept your apartment windows slightly tilted throughout the winter to keep the rooms warm while letting in a tiny bit of fresh air. You did not realize this method causes the walls around the frame to freeze while trapping humid interior air inside the room. Because you ignored the specific legal obligations of shock ventilation, condensation accumulated rapidly, ruined the structural plasterwork, and cost you €850 in landlord damage claims.
What To Do
- Buy a digital hygrometer to monitor the ambient relative humidity levels inside your main living spaces.
- Throw every window in the apartment completely wide open for five to ten minutes twice a day to flush out humid air.
- "Ich lüfte die Wohnung mehrmals täglich durch Stoßlüften." (I ventilate the apartment several times daily via shock ventilation.) — state this standard maintenance routine if your landlord inspects the property.
The Truth
Germany’s legal definitions of property maintenance treat structural ventilation as an absolute behavioral obligation for all residents. The system places the full financial liability for climate-related interior degradation onto the occupant if proper ventilation protocols cannot be proven.