Standard Width of a Staircase

IRC

• The International Residential Code (IRC), a set of regulations established by the International Code Council (ICC) for one- and two-family residential structures, has become the standard for home building and remodeling requirements throughout the United States. The code sets a minimum width for a stairway of 36 inches above the height of handrails. The minimum width including the handrails is 27 inches for staircases with two handrails and 31.5 inches for staircases with one handrail. The code makes an exception for spiral staircases, which have a minimum width requirement of 26 inches.

IBC

• Another set of regulations established by the ICC and widely adopted across the U.S., the International Building Code applies to buildings other than those covered by the IRC code. The IBC has two standards for minimum width, depending on how many people the staircase might need to serve at one time. The IBC determines this through a complex formula called occupant load. Stairs with an occupant load rating greater than 50 have a 44-inch minimum width. Staircases with a lower occupant load have a 36-inch minimum requirement.

Disability

• Congress enacted the Americans with Disabilities Act of 1990 to ensure that disabled people have appropriate access to buildings. One of the requirements involved is the creation of a special area, often in exit stairwells, called an area of rescue assistance, for people in wheelchairs who have no easy way out of a multistory building in an emergency. The area gives the disabled person a safe place to wait for rescue personnel. Stairways adjacent to the area must have a minimum width of 48 inches, according to the law.

OSHA

• The Occupational Safety and Health Administration (OSHA) creates regulations to ensure that employers provide a safe workplace for their employees. One of these regulations covers fixed stairs in industrial buildings. OSHA defines fixed stairs as stairways in and around machinery and industrial equipment or that lead to platforms or pits. Employees typically use these stairways to inspect, operate and service equipment. OSHA has set the minimum width for such stairs at 22 inches.