Rent reduction for mould

Whatever defect exists in your flat, you must report it to your landlord "without undue delay" (unverzüglich). This is intended to prevent the defect and its consequences from growing, intensifying or becoming entrenched. You also give your landlord the opportunity to look into the defect and check whether a rental defect actually exists. If a defect exists, the landlord must remedy it. Especially in the case of mould, this protects the tenant – but also the landlord's property. However, not all mould is visible. If you suspect mould, you must inform the landlord "without undue delay" in this case as well.

If you have reported the mould to your landlord and they do nothing to remedy the defect, you are in principle entitled to reduce the rent. The law even stipulates that you are not obliged to inform the landlord separately about the rent reduction.

However, you should not reduce the rent hastily. If the mould constitutes a defect that does not justify a rent reduction, or if the reduction is set too high, you will fall into arrears with part of your rent payments. If this amount adds up, the landlord may have grounds to terminate the tenancy. Therefore, always have a lawyer check whether the mould in your flat entitles you to a rent reduction and by how much the rent can be reduced.

Mould does not justify a rent reduction, for example, if the tenant has not treated the flat with due care and this is the cause of the mould.

You can find more information on how to proceed in the event of rental defects here.

A common cause of mould is incorrect ventilation and heating behaviour on the part of the tenant. Rooms should be aired regularly for 10 to 15 minutes with the windows fully open, and you should also ventilate adequately after cooking or showering. If the bathroom has no window but only an extractor fan, any mould may already lie outside the tenant's area of responsibility. In this case a rent reduction is possible, but it should always be checked by a lawyer.

Even inconspicuous things, such as badly placed furniture, can cause mould. If furniture is too close to the wall, condensation can form and lead to mould. It is therefore recommended that furniture be kept at the distance from the wall set by the skirting board. This allows air to circulate between the furniture and the wall.

You can find more information on preventing mould on the websites of the Federal Environment Agency (Umweltbundesamt) and the consumer advice centre (Verbraucherzentrale).