Every habitable space shall have not less than
one window of approved size facing directly to the
outdoors or to a court. The minimum total glazed area for every habitable space shall be 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 3 feet (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
8 percent of the floor area of the interior room or space, or not
less than 25 square feet (2.33 m2), whichever
is greater. The exterior glazing area shall be based on the total
floor area being served.
Every common hall and stairway in residential occupancies, other than in one-and two-family dwellings, shall be lighted at
all times with not less than a 60-watt standard incandescent light
bulb for each 200 square feet (19 m2) of
floor area or equivalent illumination, provided that the spacing between
lights shall not be greater than 30 feet (9144 mm). In other than
residential occupancies, interior and 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 1 footcandle (11 lux)
at floors, landings and treads.
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.