How ‘British’ is this construction: ‘a three-storey building’?
I mean, would an American understand what this means? And what do Americans usually say instead – ‘a three-floor building’ or ‘a building with three floors/levels’?
I use story/stories (albeit without the ‘e’ spelling), and floors interchangeably. I tend to use ‘levels’ to describe only houses (multi-level house or a house with two levels).
I wouldn’t consider ‘3 storey building’ British at all, aside from the minor spelling variant. Even that, my dictionary lists as an alternative spelling, but doesn’t list it as BrE, although my spell checker flags it. Any American would use and understand 3-story/3-floor building.