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Building occupancy classifications

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Example of Group F structure, the Klann Organ Company, located in Waynesboro, Virginia.

Building occupancy classifications refer to categorizing structures based on their usage and are primarily used for building and fire code enforcement. They are usually defined by model building codes, and vary, somewhat, among them. Often, many of them are subdivided.

Classifications by Group

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International Building Code

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The following is based on the International Building Code, the most commonly used building code in the United States:

  • Assembly (Group A) - places used for people gathering for entertainment, worship, and eating or drinking.[1] Examples: churches, restaurants (with 50 or more possible occupants), theaters, and stadiums. Group A is divided into five sub groups:
Group A-1 - Buildings intended for the production and viewing of performing arts or motion pictures (Examples: Movie theaters, theaters, concert halls, TV studios with a live audience)[2]
Group A-2 - Buildings intended for food and/or drink consumption. (Examples: Restaurants, cafeterias, bars, casinos, nightclubs)[2]
Group A-3 - Buildings intended for worship, recreation or amusement and other assembly uses not otherwise classified. Also includes sports facilities that do not include spectator seating. (Examples: Art galleries, courtrooms, funeral homes, gymnasium, ice rink, libraries, airport waiting area, house of worship.)[2]
Group A-4 - Buildings intended for participation in or viewing of indoor sporting events and activities with spectator seating[a]. (Examples: Arenas, indoor skating rinks, swimming pools.)[2]
Group A-5 - Buildings intended for participation in or viewing outdoor activities. (Example: Stadiums, bleachers, amusement park structures.)[2]
  • Business (Group B) - Structures where commerce, except for display and sale of goods, occurs. Also used for government offices and higher education facilities. (Examples: Banks, insurance agencies, barber/beauty salons, government buildings, and doctor's offices)[2]
Additionally, Assembly (Group A) occupancies that have are designed for 49 or fewer people are classified as Business (Group B).[1]
  • Educational (Group E) - Structures used for educational functions up to the 12th grade. (Examples: Elementary School, junior high school, high school.)[3]
  • Factory (Group F) - places where goods are manufactured or repaired that are classified as low and moderate hazard.[4]
Group F-1 Moderate Hazard - Manufacture or handling of materials that are combustible (Examples: Bakeries, furniture, industrial laundries, paper mills, print works, wood/lumber.)[3]
Group F-2 Low Hazard - Manufacture and handling of non-combustible materials. (Examples: Glass works, brick works, ice houses)[5]
Group I-1 - Structures where more than 16 people, excluding staff, live in the structure and receive care in a supervised environment and are capable of evacuating themselves. (Examples: Assisted living facilities, Group homes, alcohol/drug treatment centers)[7]
Group I-2 - Structures where more than 5 people incapable of evacuating themselves are under medical care for periods of time exceeding 24-hours. (Examples: Hospitals, nursing homes, psychiatric facilities)[7]
Group I-3 - Structures where more than 5 people are under security or restraint that prevents evacuation without assistance. (Examples: Correctional facilities, jails and prisons)[8]
Group I-4 - Structures where more than 5 people are under the supervision and care of an unrelated person, for less than 24-hours. (Example: child Day cares, adult day cares)
  • Mercantile (Group M) - places where goods are displayed and sold. Examples: Grocery stores, department stores, and gas stations.[4]
  • Residential (Group R) - Structures with sleeping accommodations.
Group R-1 - Structures where the people are staying for periods of less than 30 days. (Hotel and motels, boarding houses[b]) [9]
Group R-2 - Structures with sleeping accommodations for people living for periods of more than 30 days, or that contain three or more independent living spaces. (Example: Apartment buildings; congregate[c] dormitories, fraternity/sororities, convents/monasteries that contain 16 or more people.)[9]
Group R-3 - Structures with sleeping accommodations that are designed for less occupants, or one or two independent living spaces (Examples: Single family house, duplex, congregate[c] facilities: dormitories, fraternity/sororities, convents/monasteries that contain 15 or fewer people.)[9]
Group R-4 - Structures with sleeping accommodations for between 6 and 15 people in supervised facility receiving care, capable of evacuation without assistance. (Examples: Assisted living facilities, Group homes, alcohol/drug treatment centers)[9]
  • Storage (Group S) - places where items are stored (unless considered High-Hazard).
Group S-1 - Low-hazard - Food stuff, metal parts, glass, home appliances[10]
Also included: Public parking garages.[10]
Group S-2 - Moderate-hazard - Books and bulk paper, lumber, furniture, alcoholic beverages[10]
Also included: Aircraft hangers, motor vehicle repair facilities, and self-storage facilities[10]
  • Utility and Miscellaneous (Group U) - others. (Examples: Water towers, barns, towers.)[11]

Assembly (Group A) occupancies that are designed to hold fewer than 50 people are typically classified as being Business (Group B) occupancy, for example a small restaurant that only holds 20 people.[1][12]

The distinction between Institutional (Group I) and Residential (Group R) structures is the ability of the people to evacuate themselves, without assistance from facility staff, firefighters or other individuals.[13]

The key difference between various Residential (Group R) categories is the person's likely familiarity with the structure.[14] Hotel guests, who may only stay in a structure for a limited time usually will be unfamiliar with the building layout and unaware of alternate exit routes in the building.[14] People who spend longer periods of time living in a building are presumed to have more farmiliar with the building layout and aware of possible additional exits.[14]

Other Considerations

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Maximum Capacity sign installed on an indoor wall.

Many buildings may have multiple occupancies. These are referred to as "mixed occupancies" and the different parts will be required to meet the codes for those specific areas. An example of this is a shopping mall with underground parking. The shopping area itself is Group M (mercantile), while the parking area would qualify as Group S (storage).

In places where more than one occupancy may apply, the stricter code is usually enforced.[15]

Notes

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  1. ^ Example: Bleachers
  2. ^ With more than 10 people
  3. ^ a b Residents share common kitchen and/or bathroom facilities.

Bibliography

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  • International Code Council (2020). 2021 International Building Code. International Code Council. ISBN 9781609839550.
  • National Fire Protection Association (2024). NFPA 101 - Life Safety Code. ISBN 978-1455930562.
  • Ching, Francis; Winkel, Steven (2025). Building Codes Illustrated - A Guide to Understanding the 2024 International Building Code (8th ed.). Hoboken, New Jersey: John Wiley & Sons. ISBN 9781394284849.

References

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  1. ^ a b c International Code Council 2021, pp. 3–1.
  2. ^ a b c d e f International Code Council 2021, pp. 3–2.
  3. ^ a b International Code Council 2021, pp. 3–3.
  4. ^ a b International Code Council 2021, pp. 3-9–3-10.
  5. ^ a b International Code Council 2021, pp. 3–4.
  6. ^ International Code Council 2021, pp. 3-4–3-8.
  7. ^ a b c International Code Council 2021, p. 3-8.
  8. ^ International Code Council 2021, p. 3-9.
  9. ^ a b c d International Code Council 2021, p. 3-10.
  10. ^ a b c d International Code Council 2021, p. 3-11.
  11. ^ International Code Council 2021, p. 3-12.
  12. ^ Ching & Winkel 2025, p. 22.
  13. ^ Ching & Winkel 2025, p. 28.
  14. ^ a b c Ching & Winkel 2025, p. 32.
  15. ^ National Fire Protection Association 2024, p. 53.
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