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.