Kernrechtsfrage
Whether the landlord had to install double glazing as a remedy for the lease defect caused by increased railway noise.
Extrahierter Entscheid
No; the requested repair could be refused because the costs were disproportionate in light of the building's condition and intended demolition.
Extrahierte Begründung
A tenant's right to repair under Art. 259a CO ends when the remedy is objectively impossible or disproportionately expensive. The building was old and slated for demolition, so replacing all windows with double glazing would be excessive.