[petsfed]

I mean, most commercial and industrial buildings are approximately flat on top. There's some pitch, but its pretty minor. Its basically a solved problem, and a qualified building inspector would know how to inspect for the requirements of that particular roof style. Its unambiguously a higher-maintenance style, but it's no worse than having wood siding in terms of annual maintenance labor. Just that the consequences of failing to keep up with the labor is a lot worse.

That said, when people start throwing gardens onto their roofs, or otherwise doing things that the roof was not originally designed for, things get iffy.

[FuriouslyAdrift]

Our 800k sq ft factory has a "flat" roof. It has drains all over it that feed straight down into the building and below the concrete to a massive storm water drain.