Costs of neighbor's rainwater drainage

Questioner

My neighbour and I have garages next to each other. So under that flat roof are our garages but also part of the kitchen, the toilet and the entrance with front door. When it was built in 1977, both flat roofs each had a rainwater drain (hwa). I have lived there since 1988. My neighbour since 2017. Around 2010 I had a second drain installed, in the middle of my half of the flat roof. So inside. Because I thought that too much water remained on it and my part of the roof had a so-called zinc, a kind of valley, dent. That worked well, my roof remained largely dry. Water did remain on the neighbour's, but not alarmingly much. Sharing costs was never discussed at the time. I did it for my roof. The then neighbour thought it was all fine. Now I have renovated, my roof has been raised for insulation and our roofs are therefore clearly separated from each other. Now a lot of water remains on the neighbour's roof. Now it also appears that my second drain also drained a large part of the neighbour's rainwater. He suddenly held me responsible for the excess water on his roof last night. He wants me to pay for an extra drain on his roof. He has never previously objected to the renovation when asked. Does he have a point when he says that this is a shared roof, that I have changed that roof and therefore have to pay for an extra drain on his half?

Lawyer

Yes, because you have personally changed the course of the rainwater, what else is described in the deed of sale, because a roof that you share together, you must also maintain the components (works of hwa) together and share the costs. It is true that your neighbor has accepted the situation as it was before the purchase, but you have subsequently made changes that may cause additional inconvenience and damage to your neighbor's part of the roof than before.

Questioner

Day, Your reasoning feels unfair because I have taken measures to relieve the roof all those years. I paid for that second drain in 2012 and again during the renovation of the roof in 2018. No one has ever mentioned that my second drain also had a function in the drainage of the neighbor's water. That only became apparent now. I told the neighbor in October 2021 that we were going to renovate and asked what objections he had to that. None. He thought it was fine and is planning to do it himself. But anyway, the law apparently follows a different path in this case. If that is the case, what can the neighbor ask of me? A complete renovation like I am currently doing? Or a second drain so that a larger part of his rainwater can flow away? Where does his responsibility begin?

Lawyer

If your neighbour has benefited from a number of repairs that you carried out yourself and for which you should in fact have asked permission in advance, but your neighbour had to share in the costs. Can you still use that argument to settle? This mainly concerns the costs that you incurred in 2018, also for the new owner. You both had responsibility here to jointly repair hwa for both costs, then and now. And at this moment it is best to find a reasonable solution together, taking into account that you have previously had repairs carried out and benefited from them. Demanding the utmost from a neighbour will not succeed in a courtroom, you must continue to take each other and each other's (financial) interests into account.

Questioner

Thank you very much for your comments. I will take them into account in my conversation with the neighbor. With kind regards