Flat roof - Is it really sealed or are there problems with water?

Hello everyone,

we have a small bay window on the ground floor in our construction project, which should get either a small sheet metal roof or a flat roof. In the past, flat roofs always had problems with moisture. Does anyone of you have experience with that? How is it today, is the whole thing sealed or are there still recurring problems?

The flat roof would actually be my favorite for aesthetic reasons.

Regards

In terms of materials, this is not an issue in 2018. There are UV-resistant, permanently elastic, and dense sealants and adhesives to, for example, bond galvanized steel so that it is pot-tight. But... it must then also be worked on accordingly carefully. This is rather the crux. If the construction tradesmen were as meticulous as shipbuilders, we would only have tight flat roofs. But the construction tradesmen are not like that.