What are our rights and obligations regarding renovating a shared chimney?

Questioner

Our neighbour has a leak in her house which she believes is caused by the shared chimney. We have now discussed the options in a conversation. Our side of the shared chimney has already been covered with slate by the previous occupants and has been well maintained. The only thing that would need to be done is to cover the top as the chimney is no longer used. The neighbour's side is in much worse condition. Loose bricks, aged mortar, etc. The leak is probably also caused by this. Now we have asked the neighbor via app for a quote so that we would get insight into what it would cost. However, we have not received this and it was also not indicated that it would be made and when. And so it has already been made without our 'permission'. Now the neighbor expects us to pay the entire bill. Is this allowed?

Lawyer

No, at the very least you must have insight into the cause of the leak and if it turns out that it is caused by negligent maintenance on the part of the neighbor, you of course do not have to pay this bill.