Maintenance is the landlord's duty (§ 535 BGB)
The landlord must keep the flat in contractual condition for the entire tenancy. Heating, water, wiring, windows, mould not caused by your ventilation habits — all fundamentally the landlord's responsibility. Standard-form clauses shifting maintenance wholesale onto tenants are regularly invalid.
The minor-repairs clause — tightly limited
A Kleinreparaturklausel is only valid within narrow limits: it may cover only items you touch daily (taps, light switches, window handles), needs a per-repair cap (courts accept roughly €75–120), and an annual cap. If any element is missing, the whole clause fails — and you pay nothing. Mietsicht checks your clause against exactly these criteria.
Report immediately — or you become liable (§ 536c BGB)
Defects must be reported to the landlord without undue delay. Staying silent risks two things: liability for consequential damage, and losing rent-reduction rights for the period before you reported. Report in writing, describe the defect concretely, add photos and the date.
Rent reduction only after reporting (§ 536 BGB)
Significant defects reduce the rent by law — but only from the report onward, and the right percentage is highly case-specific. Overreaching reductions are the biggest risk in a tenancy: accumulated arrears can justify termination. Mietsicht helps with the evidence-proof notice and a repair deadline; for the reduction percentage we deliberately point to a tenants' association or lawyer.