IRC section R305 is amended to read as follows:
R305.1
Minimum height, new buildings.
Habitable space, hallways, bathrooms, toilet rooms, laundry rooms, and
portions of basements containing these spaces shall have a ceiling height of
not less than 7 feet (2134 mm). The required height shall be measured from the
finish floor to the lowest projection from the ceiling.
Exceptions:
1. For rooms with sloped ceilings, at least
50 percent of the required floor area of the room shall have a ceiling height
of at least 7 feet (2134 mm) and no portion of the required floor area may have
a ceiling height of less than 5 feet (1524 mm).
2. Bathrooms shall have a minimum ceiling
height of 6 feet 8 inches (2032 mm) at the center of the front clearance area
for water closets, bidets, or sinks. The ceiling height above fixtures shall be
such that the fixture is capable of being used for its intended purpose. A
shower or tub equipped with a showerhead shall have a minimum ceiling height of
6 feet 8 inches (2032 mm) above a minimum area 30 inches (762 mm) by 30 inches
(762 mm) at the showerhead.
R305.1.1
Basements, new buildings.
Portions of basements that do not contain habitable space, hallways,
bathrooms, toilet rooms, and laundry rooms shall have a ceiling height of not
less than 6 feet 8 inches (2032 mm).
Exception: Beams, girders, ducts, or other
obstructions may project to within 6 feet 4 inches (1931 mm) of the finished
floor.
R305.2
Alterations to existing building basements. Alterations to
portions of existing basements shall comply with the provisions of this
section.
R305.2.1
Minimum ceiling
height, existing buildings. Alterations to existing basements or
portions thereof shall have a ceiling height of not less than 6 feet 4 inches
(1931 mm), including beams, girders, ducts, or other obstructions.
R305.2.1.1
Bathroom plumbing fixture
clearance. Bathrooms shall have a minimum ceiling height of 6 feet 4
inches (1931 mm) at the center of the front clearance area for water closets,
bidets, or sinks. A shower or tub equipped with a showerhead shall have a
minimum ceiling height of 6 feet 4 inches (1931 mm) above a minimum area 30
inches (762 mm) by 30 inches (762 mm) at the wall where the showerhead is
placed. The ceiling may have slopes or soffits that do not infringe on the
height required for the plumbing fixture.
R305.2.2
Minimum stairway headroom,
existing buildings. Alterations to existing basement stairways shall
have a minimum headroom in all parts of the stairway not less than 6 feet 4
inches (1931 mm) measured vertically from the sloped line adjoining the tread
nosing or from the floor surface of the landing or platform on that portion of
the stairway.
Exception; Where the nosings of treads at the side
of a flight extend under the edge of a floor opening through which the stair
passes, the floor opening shall be allowed to project horizontally into the
required headroom a maximum of 4-3/4 inches (121 mm).
