ᐅ Mold Under the Bathroom Ventilation System

I rent a small apartment with a bathroom that has no windows. There is a ventilation system for air circulation, but it constantly causes problems. In damp and cold weather, water drips from the ventilation grille and soaks the plaster underneath. By now, water stains and mold spots have probably formed. I tried to fix the problem by heating more intensely, but that didn’t help. I don’t think the water is coming from outside (rain), as the amount is too small. It looks more like condensation.
Does anyone have any ideas?

It could be condensation; to determine why so much condensation is occurring, an on-site investigation would be necessary (this should ideally be addressed by your landlord).

The ventilation capacity is probably too low—either the duct is too long or the fan is underpowered. Perhaps an electrician could inspect the fan, as the issue might be with the motor.

When I was still renting, I had the same problem. The ventilation for windowless bathrooms is usually undersized. After showering or bathing, there is more humidity than a small fan can quickly exhaust. Most of the time, water condenses inside the cold metal housing of the fan, and from there the condensation water runs down the wall. There isn’t much you can do about it; most landlords won’t install a larger fan for this reason. I simply repainted the area under the fan more frequently with mold-resistant paint and accepted it.

The landlord is responsible and must have the mold removed. However, the source of the mold growth must be thoroughly investigated beforehand. This can only be determined by a qualified expert.

One of the common problems with interior bathrooms is that the exhaust fan is often undersized, causing moisture from condensation to accumulate between the seals. This frequently leads to mold forming in the seals. A more powerful fan often helps, but the landlord needs to be consulted in this case.

I know exactly what you mean, and a larger exhaust fan makes a big difference. But the landlord has to have an interest in preventing mold growth. For that, they need to invest in a bigger fan, and without that, the problem will persist.