International Building Code 1205.1
General. Every space intended for human occupancy
shall be provided with natural light by means of exterior glazed
openings in accordance with Section 1205.2 or shall be provided
with artificial light in accordance with Section 1205.3.
Exterior glazed openings shall open directly onto a public way
or onto a yard or court in accordance with Section 1206.
International Building Code 1205.2
Natural light. The minimum net glazed area shall not
be less than 8 percent of the floor area of the room served.
Adjoining spaces. For the purpose of natural
lighting, any room is permitted to be considered as a portion
of an adjoining room where one-half of the area of the common
wall is open and unobstructed and provides an opening
of not less than one-tenth of the floor area of the interior
room or 25 square feet (2.32 m2), whichever is greater.
Exception: Openings required for natural light shall be
permitted to open into a thermally isolated sunroom
addition or patio cover where the common wall provides
a glazed area of not less than one-tenth of the floor area of
the interior room or 20 square feet (1.86 m2), whichever
is greater.
Exterior openings. Exterior openings required by
Section 1205.2 for natural light shall open directly onto a
public way, yard or court, as set forth in Section 1206.
Exceptions:
1. Required exterior openings are permitted to open
into a roofed porch where the porch:
1.1. Abuts a public way, yard or court.
1.2. Has a ceiling height of not less than 7 feet
(2134 mm).
1.3. Has a longer side at least 65 percent open
and unobstructed.
2. Skylights are not required to open directly onto a
public way, yard or court.
250 2006 INTERNATIONAL BUILDING CODE
INTERIOR ENVIRONMENT
International Building Code 1205.2.1
Adjoining spaces. For the purpose of natural
lighting, any room is permitted to be considered as a portion
of an adjoining room where one-half of the area of the common
wall is open and unobstructed and provides an opening
of not less than one-tenth of the floor area of the interior
room or 25 square feet (2.32 m2), whichever is greater.
Exception: Openings required for natural light shall be
permitted to open into a thermally isolated sunroom
addition or patio cover where the common wall provides
a glazed area of not less than one-tenth of the floor area of
the interior room or 20 square feet (1.86 m2), whichever
is greater.
International Building Code 1205.2.2
Exterior openings. Exterior openings required by
Section 1205.2 for natural light shall open directly onto a
public way, yard or court, as set forth in Section 1206.
Exceptions:
1. Required exterior openings are permitted to open
into a roofed porch where the porch:
1.1. Abuts a public way, yard or court.
1.2. Has a ceiling height of not less than 7 feet
(2134 mm).
1.3. Has a longer side at least 65 percent open
and unobstructed.
2. Skylights are not required to open directly onto a
public way, yard or court.
250 2006 INTERNATIONAL BUILDING CODE
INTERIOR ENVIRONMENT
International Building Code 1205.3
Artificial light. Artificial light shall be provided that is
adequate to provide an average illumination of 10 foot-candles
(107 lux) over the area of the room at a height of 30 inches (762
mm) above the floor level.
International Building Code 1205.4
Stairway illumination. Stairways within dwelling
units and exterior stairways serving a dwelling unit shall have
an illumination level on tread runs of not less than 1 foot-candle
(11 lux). Stairs in other occupancies shall be governed by
Chapter 10.
Controls. The control for activation of the
required stairway lighting shall be in accordance with the
ICC Electrical Code.
1205.5 Emergency egress lighting. The means of egress shall
be illuminated in accordance with Section 1006.1.
International Building Code 1205.4.1
Controls. The control for activation of the
required stairway lighting shall be in accordance with the
ICC Electrical Code.
1205.5 Emergency egress lighting. The means of egress shall
be illuminated in accordance with Section 1006.1.