Mold in Your Rental Apartment in Germany: Tenant Rights

Is the Landlord Responsible for Mold in Germany?

Mold in a rental apartment is a serious defect under German tenancy law. Under § 536 BGB – a provision of the BGB (German Civil Code) – tenants have the right to a defect-free apartment. If mold occurs due to structural defects – such as leaky windows, insufficient insulation, or faulty sealing – the landlord is obligated to fix it. This applies to every residential tenancy in Germany, regardless of your nationality or what your lease says.

Structural Defect or “You Didn’t Ventilate Enough”?

Landlords in Germany very often argue that mold was caused by the tenant’s heating and ventilation habits – you may hear the word Lüften (airing out the apartment), which is taken surprisingly seriously in Germany. However, the burden of proof lies with the landlord: they must demonstrate that the tenant caused the mold. If they cannot, a structural defect is presumed.

• Structural causes: Thermal bridges, leaky joints, inadequate ventilation in bathrooms without windows
• Tenant behavior: Only in cases of demonstrably insufficient ventilation (e.g., permanently closed windows with high moisture production)

How Much Can I Reduce My Rent for Mold in Germany?

In Germany, a Mietminderung (rent reduction) is your statutory right when your apartment has a defect. The amount depends on the extent of the infestation. Courts have awarded between 5% and 100% rent reduction depending on severity:

• Minor mold in one room: approx. 5–10%
• Large-scale infestation in the bedroom: approx. 15–20%
• Health-threatening mold in multiple rooms: up to 50%
• Apartment uninhabitable: up to 100%

Calculate your individual rent reduction →

How Do I Report Mold to My Landlord? (Step by Step)

1. Document the mold – Photos with dates, size of the affected area
2. Send a defect notice (Mängelanzeige) to the landlord – In writing by registered mail, with a deadline for remediation. Note that correspondence with German landlords should be in German – a letter in English may simply be ignored or rejected. Our service generates the letter in legally correct German for you. Create defect notice →
3. Announce the rent reduction – After the deadline expires, you may reduce your rent

If the dispute escalates, consider joining a local Mieterverein (tenant association) – a membership-based organization that provides legal advice to tenants for a small annual fee.

Important: Report the mold to your landlord immediately. Concealing a defect puts you at risk of liability for damages.