Mold on walls after tenant moves out due to poor ventilation?

Hello,

Our tenants have been moving out gradually for about 2 weeks. Today I went into the apartment and found mold in several places. I have attached the largest one by far. Unfortunately, the tenants turned the heating completely off and it used to be cozy and warm before. I assume that proper ventilation was not done.

The mold can be wiped off. Would you renew the wallpaper? Do you have a tip for a mold remover?

Thanks in advance!

First, the apartment has poor forced ventilation. This is especially important in rental apartments because tenants do not ventilate as consistently as if it were their property. Mold is removed with a solution of Danklorix and water in about a one to three ratio. Then it is gone. Dead. It really hates chlorine.

Wallpaper is a bit of a different matter. You might be able to wipe the surface superficially, but what is in the fiber and initially invisible, you don’t know. It can quickly come back or look even worse behind the wallpaper than on the wallpaper. I would take that piece down.

Isn't that what the deposit is for in such cases?

für solche Fälle gibt's doch die Kaution?

Is that then a defect for the deposit?

Is that a defect concerning the deposit?

What does the rental agreement say? If it states (as I know from my rental times) to ventilate sufficiently and it was not done, then withhold the deposit.

But whether to start trouble over a little wallpaper... I think the tenant is also allowed to fix the defect themselves.