How do you call a two-floor apartment in a bigger apartment building? I know that an apartment with two floors is called a duplex. But how do you call a two-floor apartment in a bigger apartment building? Like, there are 8 floors of a building but each apartment occupies 2 floors. The stairs are inside the apartments.Thanks to John, he said it's called a Maisonette. However, the definition of maisonette is "a flat that usually has a separate door to the outside from other flats in the same building", but what I'm looking for is more like a ... duplex room in a hotel. You get on like, the 24th floor of the building using the public stairs or elevator, then you can enter your own 2-storey home.