When mold growth occurs in rented apartments, there are always disputes between the landlord and tenant. But why is that so? The rule in the event of mold infestation stipulates that renovation / removal must be carried out at the landlord's expense if structural defects or damage are causing the mold infestation. The tenant has to pay the costs if mold develops due to "incorrect usage behavior" (e.g. incorrect, poor ventilation, H.eizen). If the tenant is significantly impaired due to mold growth for which he is not responsible, he has the right to reduce the rent - in accordance with the impairment.
However, it is usually very difficult to prove what caused the mold. In the event of a dispute, an appropriate expert is often called in. But even this does not always create clarity - so the result of the expert is often doubted and fought afterwards by the party that did not commission him and against whom the result is against.
Tip for tenants: Immediately after the occurrence of a significant mold infestation or if a mold check has been carried out that shows potential mold infestation in the findings, inform the landlord in writing and request a clarification of the cause and removal options and point out a possible rent reduction.
Tip for landlords: Before renting out a residential unit or after renovating an apartment, carry out a mold measurement. This gives you and the tenant security that the residential unit has been handed over for occupancy free of mold. Give the tenant a guide on how mold can be avoided through correct living behavior (e.g. "Living tips to prevent mold").