How do I enforce repair of a leak at my upstairs neighbors?

Questioner

My upstairs neighbors rent their apartment, I bought mine. Now I have an increasingly clear moisture ring in my plasterwork on the ceiling, diagonally under their bathroom. The maintenance service of the landlord came to have a look. After a lot of 'I don't know' and 'we'll try something' they did something (without feedback or notification) and the problem is still not solved. So much moisture has already passed over it that it is no longer clearly visible when it is wet again. Who should I now address for negligence? The tenant, or the landlord as owner? How and with whom can I enforce that it is properly remedied?

Lawyer

You can contact both of them, but it is obvious that you should write to the tenant as the perpetrator and hold him liable for the damage caused by a leak caused by him.