A. Habitable Spaces. Every habitable space shall have not less than one (1) window of approved size facing directly to the outdoors or to a court. The minimum total glazed area for every habitable space shall be eight (8) percent of the floor area of such room. Wherever walls or other portions of a structure face a window of any room and such obstructions are located less than three (3) feet (nine hundred fourteen (914) mm) from the window and extend to a level above that of the ceiling of the room, such window shall not be deemed to face directly to the outdoors nor to a court and shall not be included as contributing to the required minimum total window area for the room. Exception: Where natural light for rooms or spaces without exterior glazing areas is provided through an adjoining room, the unobstructed opening to the adjoining room shall be not less than eight (8) percent of the floor area of the interior room or space, but a minimum of twenty-five (25) square feet (2.33 m²). The exterior glazing area shall be based on the total floor area being served.

B. Common Halls and Stairways. Every common hall and stairway in residential occupancies, other than in one (1) and two (2) family dwellings, shall be lighted at all times with not less than a sixty (60) watt standard incandescent light bulb for each two hundred (200) square feet (nineteen (19) m²) of floor area or equivalent illumination; provided, that the spacing between lights shall not be greater than thirty (30) feet (nine thousand one hundred forty-four (9,144) mm). In other than residential occupancies, means of egress, including exterior means of egress, stairways shall be illuminated at all times the building space served by the means of egress is occupied with not less than one (1) foot-candle (eleven (11) lux) at floors, landings and treads.

C. Other Spaces. All other spaces shall be provided with natural or artificial light sufficient to permit the maintenance of sanitary conditions, and the safe occupancy of the space and utilization of the appliances, equipment and fixtures.