R305.1 Minimum height.¹ Habitable rooms, hallways, corridors, bathrooms, toilet rooms, laundry rooms and basements shall have a ceiling height of not less than 7 feet. The required height shall be measured from the finished floor to the lowest projection from the ceiling.

Exceptions:

1. 1. Beams, girders, pipes, ducts or other obstructions spaced not less than 4 feet on center shall be permitted to project not more than 6 inches below the required ceiling height.
2. 2. Basements without habitable spaces shall have a ceiling height of not less than 6 feet, 8 inches. Beams, girders, pipes, ducts or other obstructions shall be permitted to project not more than 4 inches below the required ceiling height.
3. 3. Not more than 50 per cent of the required area of a habitable room or space is permitted to have a sloped or furred ceiling less than 7 feet in height. No portion of the required floor area shall be less than 5 feet in height.
4. 4. Bathrooms are permitted to have sloped or furred ceilings, but shall have a minimum ceiling height of 6 feet, 8 inches over the fixtures and at the front clearance area for the fixtures as shown in Figure R307.2. A shower or tub equipped with a showerhead shall have a minimum ceiling height of 6 feet, 8 inches above a minimum area 30 inches by 30 inches at the showerhead.
5. 5. Ceiling height in existing basements being converted to habitable space shall be not less than 6 feet, 10 inches clear except under beams, girders, pipes, ducts or other obstructions where the clear height shall be a minimum of 6 feet, 6 inches.