(A) General. Every habitable room shall have at least 1 window or skylight facing directly to the outdoors. The minimum total window area, measured between stops, for every habitable room shall be 10% of the floor area of a room. Whenever walls or other portions of structures face a window or any room and light obstructing structures are located less than 5 feet from the window and extend to a level above that of the ceiling of the room, a window shall not be deemed to face directly to the outdoors and shall not be included as contributing to the required minimum total window area. Whenever the only window in a room is a skylight-type window in the top of a room, the total window area of a skylight shall equal at least 15% of the total floor area of the room.
(B) Habitable rooms. Every habitable room shall have at least 1 window or skylight which can easily be opened, or another device as will adequately ventilate the room. The total openable window area in every habitable room shall be equal to at least 45% of the minimum window area size or minimum skylight-type window size as required or shall have other approved, equivalent ventilation.
(C) Bathroom and water closet rooms. Every bathroom and water closet compartment shall comply with the light and ventilation requirements for habitable rooms except that no window or skylight shall be required in adequately ventilated bathrooms and water closet rooms equipped within an approved ventilation system.
(1988 Code, § 4-29)