The number of floors in an apartment building and its quality depends on the level of the city – on higher levels of the city better and more expensive apartment buildings will be available. An apartment may be bought or sold the same as a house.
Worker's quarters are two-storey lower-level apartment buildings where NPCs live who work at manufactures on the lower positions, service staff that work around the city. It's free social accommodation. It's closed for player building – a rabbit hole.
A house or apartment may be rented instead of buying. The rented real estate will have a list of limitations in the game.
Also, lots of lands will be available for buying, where you can build your own house starting from a basement, or you always may just pitch a tent.
There will be a system of inheritance and wills.