The provisions of this code shall apply to all buildings or portions thereof. Such occupancies in existing buildings may be continued as provided in the Building Code, except such structures as are found to be substandard as defined in this code.
Where any building or portion thereof is used or intended to be used as a combination apartment house-hotel, the provisions of this code shall apply to the separate portions as if they were separate buildings.
Every rooming house or lodging house shall comply with all the requirements of this code for dwelling.