A. Generally: Every habitable room shall have a ventilation system adequate for the purpose for which the room is used. Natural ventilation shall be deemed to be adequate for habitation when the total area openable to the outside air (by means of windows, louvers, monitors or other direct openings excluding doors) is five percent (5%) of the floor area of the habitable room, except that when:
1. Any portion of the room is more than sixteen feet (16') from a required opening, the aggregate clear area of openings shall be not less than six percent (6%).
2. A room has openable areas on two (2) or more sides thereof, the total openable area shall be at least four percent (4%) of the total floor area of such room.
3. The openable area faces a wall or other obstruction at a distance of less than ten feet (10'), the effective area shall be computed at not more than eighty percent (80%) of the actual openable area.
4. The openable area opens onto an enclosed porch, the enclosed porch shall have an openable area of at least three (3) times the total required area of the openings onto such porch.
B. Kitchen With Floor Area Of Less Than Seventy Square Feet: A kitchen with a floor area of less than seventy (70) square feet may be without either mechanical or natural ventilation if there is an opening of not less than thirty two (32) square feet between the kitchen and another room in the same family unit and if the room into which the kitchen opens has the ventilation requirements of subsection A above.
C. Toilet And Bathroom: Every toilet room and bathroom shall have adequate ventilation which may be either an openable window with an openable area of five percent (5%) of the floor area, mechanical ventilation in compliance with the foregoing requirements of this Section, or a gravity vent flue constructed with incombustible material leading to the roof of the building or a combination of any of these. The gravity vent shall be computed at an aggregate clear area of not less than five percent (5%) of the floor area of the room with a minimum area of at least one hundred twenty (120) square inches. Gravity vents shall be provided with a weather cap, directional vane or rotary-type ventilation on tile roof. (1997 Code)