Standard Width of a Residential, Institutional, or Industrial Staircase

Staircases can be categorized into one of the following three types:

  • Private – Intended to be used for only one dwelling (domestic stair case)
  • Institutional and Assembly Stair – Serving a place where a substantial number of
    people will gather (This type of stair is used in hospitals, schools, shops etc.)
  • Other Stair – For all other buildings (Used in flats and other buildings)

To ensure the well-being of users, building authorities have instituted minimum standards for various dimensions of stairways. Stair codes are designed for the safety of the consumer and vary from state to state, county to county, and city to city.  It is advisable to know well ahead what your limitations and restrictions are. One of the main concerns of most codes lies in creating a minimum width for every staircase.

Small Family Homes with Modern Interiors (

1 – The International Residential Code (IRC)

The International Residential Code (IRC) is a comprehensive, stand-alone residential code that creates minimum regulations for one- and two-family dwellings of three stories or less. It brings together all building, plumbing, mechanical, fuel gas, energy and electrical provisions for one- and two-family residences.


The code sets:

  • a) Minimum width for a stairway of 36 inches above the height of handrails
  • b) Minimum width including the handrails is 27 inches for staircases with two handrails
  • c) Minimum width is 31.5 inches for staircases with one handrail
  • d) The code makes an exception for spiral staircases, which have a minimum width requirement of 26 inches.

2 – The International Building Code (IBC)

The International Building Code (IBC) is a model building code developed by the International Code Council (ICC) and it has been adopted throughout most of the United States.


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. This is calculated through a complex formula called occupant load.

So, the width of stairways shall not be less than 44 inches (1118 mm).

Exceptions: Stairways serving an occupant load of 50 or less shall have a width of not less than 36 inches (914 mm).

3 – The Occupational Safety and Health Administration (OSHA)

The United States Occupational Safety and Health Administration (OSHA) is an agency of the USA Department of Labor. OSHA federal regulations cover most private sector workplaces.


One of these regulations covers fixed stairs in industrial buildings. OSHA has set the minimum width for such stairs at 22 inches.

4 – Persons with Disabilities

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.

Stairways adjacent to the area must have a minimum width of 48 inches.