3-floor house: My wife and I would live on the 3rd floor in a separate apartment with kitchen and toilet etc. The stairs and hallway run through the lower floors, which another man occupies, like a classic single-family house where only the top floor is a separate unit. Is this permissable?

Ustadh AbdulAziz al-Haqqan

I would prefer a separate exit and entrance as this will be a hassle for you. Also it is not allowed if there isn't a separation between you and you lock it etc. As and advice though, look for something else where you are separate and have your own entrance.