Fire-rated doors in two-family

I’m doing an extensive renovation that will result in a two-family house. I’m told by the architect that I need fire-rated doors in the hallway connecting the two units but I can’t find the provision showing the requirement. I have 5 doors that connect to a hallway and hence a considerable amount of expense if i go fire-rated. Seeking advice from anyone was able to avoid the requirement in connection with an ALT 1 filed renovation.