Building Occupancy Classification – Occupancy Types Explained

Author : Building Code Trainer

Properly classifying the use and occupancy of a building is an important task that sets the tone for how a structure is designed as associated with its risk level.

When selecting the correct occupancy classification the buildings components and features are designed as such to ensure a reasonable level of protection is provided to the building and its occupants.

These components and features can include but are not limited to the buildings height, area, type of construction, fire resistance, fire protection, means of egress system, and interior finishes. How these features apply to a building is based on its occupancy classification, therefore properly classifying a building is important.

Chapter 3 of the 2021 International Building Code (IBC) sets the requirements of how to identify a buildings occupancy characteristics based on how a space or spaces are used within a building.

In addition to the various types of occupancy classifications, several of these classifications have specific group classifications which have many things in common with the main occupancy but some differences in the level of risk they can pose.

Before we get into the details of each specific occupancy group, here is a table that gives the overall occupancy classifications and the number of groups in each one:

Now let’s look at how each occupancy group is defined to better understand how a space is used within each occupancy type.

Group A Occupancy – Assembly

What is a Group A Occupancy?

A group A assembly occupancy is a use where people gather for the purpose of civic, social, religious function, recreation, food/drink consumption, or waiting for transportation.

What Are Examples of a Group A Occupancy?

Group A occupancies are broken down into 5 groups.

Group A-1:

A space used for assembly, usually with fixed seating which is intended for production and viewing of performing arts or a motion pictures.

This includes but is not limited to the following examples:

• Motion picture theaters
• Symphony and Concert halls
• Television and Radio studios that admit an audience
• Theaters

Group A-2:

A space used for assembly that is intended for food and/or drink consumption.

This includes but is not limited to the following examples:

• Banquet Halls
• The gaming areas of Casinos
• Nightclubs
• Restaurants, Cafeterias and Similar Dining Facilities
• Taverns and Bars

Group A-3:

A spaced used for assembly that is intended for worship, recreation or amusement and other assembly uses that are not classified within any other Group A type.

This includes but is not limited to the following examples:

• Amusement Arcades
• Art Galleries
• Bowling Alleys
• Community Halls
• Courtrooms
• Dance Hall that do not include any food or drink consumption
• Exhibition Halls
• Funeral Parlors
• Gymnasiums without spectator seating
• Indoor swimming pools without spectator seating
• Indoor tennis courts without spectator seating
• Lecture Halls
• Libraries
• Museums
• Place of religious worship
• Pool and billiard parlors
• Waiting areas in transportation terminals

Group A-4:

A space used for assembly that is intended for viewing indoor sporting events and activities with spectator seating.

This includes but is not limited to the following examples:

• Arenas
• Skating rinks
• Swimming Pools
• Tennis Courts

Group A-5:

A space used for assembly that is intended for participation in or viewing outdoor activities.

This includes but is not limited to the following examples:

• Amusement park structures
• Bleachers
• Grandstands
• Stadiums

Exceptions to Group A Occupancies

There are times where an assembly space is not classified as a Group A occupancy. The code lists outs the following conditions:

Small Buildings or Tenant Spaces

When a space within a building, or the building itself, is used for assembly purposes where the occupant load is less than 50 persons, then the classification of this space or building is considered a Group B occupancy.

Technically by definition these spaces or buildings are considered assembly spaces, however due to their low occupant load, they have a lower risk associated to them than a typical assembly space.

Small Assembly Spaces

There are two types of “small spaces” where the code will consider an assembly space a different type of occupancy.

1. When a room or space is designed for an occupant load of less than 50 persons and is accessory to another occupancy, it can be classified as a Group B occupancy or as part of that occupancy.
2. When a room or space is less than 750 square feet in area and accessory to another occupancy, then it can be classified as a Group B occupancy or as part of that occupancy.

Associated with a Group E Occupancy

When a room or space is used for assembly purposes and associated with a Group E occupancy, it is not considered a separate occupancy.

Accessory to Places of Worship

Accessory religious educational rooms and auditoriums that have an occupant load less than 100 persons per room or space are not considered separate occupancies.

Special Amusement Areas

Special amusement areas are considered special occupancies and are required to comply with Section 411.

Group B Occupancy – Business

What is a Group B Occupancy?

A group B business occupancy is a use of a building that functions as an office or a professional or a service type transaction.

What Are Examples of a Group B Occupancy?

Examples of a Group B occupancy include but are not limited to the following examples:

• Airport traffic control towers
• Ambulatory care facilities
• Animal hospitals, kennels and pounds
• Bank
• Barber and beauty shops
• Car wash
• Civic administration
• Clinic, outpatient
• Dry cleaning and laundries
• Educational occupancies for students above the 12th grade
• Electronic data processing
• Food processing establishments and commercial kitchens that are not associated with restaurants, cafeterias and similar dining facilities not more than 2,500 square feet in area.
• Laboratories used for testing and research
• Motor vehicle showrooms
• Pose offices
• Print shops
• Professional services such as architects, attorneys, dentists, physicians, engineers, etc…
• Radio and Television stations
• Telephone exchanges
• Training and Skill Development not in a school or academic program and where not classified as a Group A occupancy.

Airport Traffic Control Towers

Airport traffic control towers are considered special occupancies and are required to comply with Section 412.2.

Ambulatory Care Facilities

Ambulatory care facilities are considered special occupancies and are required to comply with Section 422.

Higher Education Laboratories

Higher educational laboratories are considered special occupancies and are required to comply with Section 428.

Group E Occupancy – Educational

What is a Group E Occupancy?

A Group E occupancy is a use of a building where six or more persons at any one time occupy a space for educational purposes through the 12th grade.

Day Care Facilities are also classified under Group E. This includes spaces that are occupied by more than five children that are older than 2-1/2 years of age who receive educational, supervision or personal care services for less than 24 hours per day.

The code does make 3 clarifications regarding Day Care Facilities as to when they are not classified as a Group E occupancy.

1. Spaces used within a place of religious worship that provide such day care services during the religious function shall be classified as part of the primary occupancy.
2. Facilities that have 5 of less children that receive such day care services shall be classified as part of the primary occupancy.
3. A day care service within a dwelling unit that has 5 or less children shall be classified as a Group R-3 occupancy.

Storm Shelters within Group E Occupancies

Storm shelters within Group E occupancies are considered special occupancies and are required to comply with Section 423.5.

Group F Occupancy – Factory and Industrial

What is a Group F Occupancy?

A group F occupancy is a use of a building that involves assembling, disassembling, fabricating, finishing, manufacturing, packaging, repair, and processing operations that would not be otherwise classified as a Group H or Group S occupancy.

What Are Examples of a Group F Occupancy?

Group F-1:

A space used for factory industrial uses not classified as occupancy group F-2. Group F-1 is also known as a moderate-hazard factory use.

This includes but is not limited to the following examples:

• Aircraft manufacturing, not to include repair
• Appliances
• Athletic equipment
• Automobiles and other motor vehicles
• Bakeries
• Beverages: over 16% alcohol content
• Bicycles
• Boats
• Brooms or brushes
• Business machines
• Cameras and photo equipment
• Canvas or similar fabric
• Carpets and rugs (includes cleaning)
• Clothing
• Construction and agricultural machinery
• Disinfectants
• Dry cleaning and dyeing
• Electric generation plants
• Electronics
• Energy storage systems (ESS) in dedicated use buildings
• Engines (including rebuilding)
• Food processing establishments and commercial kitchens not associated with restaurants, cafeterias and similar dining facilities more than 2,500 square feet in area.
• Furniture
• Hemp products
• Jute products
• Laundries
• Leather products
• Machinery
• Metals
• Millwork (sash and door)
• Motion pictures and television filming (without spectators)
• Musical instruments
• Optical goods
• Paper mills or products
• Photographic film
• Plastic products
• Printing or publishing
• Recreational vehicles
• Refuse incineration
• Shoes
• Soaps and detergents
• Textiles
• Tobacco
• Trailers
• Upholstering
• Water/sewer treatment facilities
• Wood; distillation
• Woodworking (cabinet)

Group F-2:

A space used for the fabrication or manufacturing of noncombustible materials where during the finishing or packing process does not involve a significant fire hazard. Group F-2 is also known as a low-hazard factory use.

This includes but is not limited to the following examples:

• Beverages: 16% alcohol content or less
• Brick and masonry
• Ceramic products
• Foundries
• Glass products
• Gypsum
• Ice
• Metal Products, both fabrication and assembly

Aircraft Manufacturing Facilities

Aircraft manufacturing facilities are considered special occupancies and are required to comply with Section 412.6.

Group H Occupancy – High Hazard

What is a Group H Occupancy?

A group H occupancy is a use that involves the manufacturing, processing, generation or storage of materials that can constitute a physical or health hazard. Group H occupancies are classified into 5 high hazard areas that identify the type of hazard for each group. These 5 areas are as follows: H-1, H-2, H-3, H-4, and H-5.

What Are Examples of Group H Occupancies?

Group H-1:

A space, building, or structure that contains materials that would pose a detonation hazard. This includes but is not limited to the following examples found here.

Group H-2:

A space, building, or structure that contains materials that would pose a deflagration hazard or a hazard from accelerated burning. This includes but is not limited to the following examples found here.

Group H-3:

A space, building, or structure that contains materials that readily support combustion or that pose a physical hazard. This includes but is not limited to the following examples found here.

Group H-4:

A space, building, or structure that contains materials that are health hazards. This includes but is not limited to the following examples found here.

Group H-5:

Semiconductor fabrication facilities and comparable research and development areas which use hazardous production materials (HPM) and where the aggregate quantity of materials used is in excess of those materials listed in Tables 307.1(1) and 307.1(2).

Group I Occupancy – Institutional

What is a Group I Occupancy?

A group I occupancy is a use in which care or supervision is provided to people who are or are not capable of self-preservation without physical assistance or in which people are detained for penal or correctional purposes or in which the liberty of the occupants is restricted.

What Are Examples of a Group I Occupancy?

Group I-1:

A space, building, or structure used by more than 16 people, not including staff, who reside on a 24-hour basis within a supervised environment and receive custodial care.

This includes but is not limited to the following examples:

• Alcohol and drug centers
• Assisted living facilities
• Congregate care facilities
• Group homes
• Halfway houses
• Residential board and care facilities
• Social rehabilitation facilities

In addition, group I-1 occupancies must be identified as either a Condition 1 or Condition 2.

I-1 Condition 1 includes buildings where all people who receive custodial care without any assistance are capable of responding to an emergency situation to evacuate a building.

I-1 Condition 2 includes buildings where any person who receives custodial care requires limited verbal or physical assistance while responding to an emergency situation to evacuate a building.

Also note the code clarifies that a facility that houses no fewer than 6 and no more than 16 people who receive custodial care shall be classified as a Group R-4 occupancy, while a facility with 5 or less people receiving custodial care shall be classified as a Group R-3 occupancy.

Group I-2:

A building or structure used for medical care on a 24 hour basis for more than 5 people who are not capable of self preservation.

This includes but is not limited to the following examples:

• Foster care facilities
• Detoxification facilities
• Hospitals
• Nursing homes
• Psychiatric hospitals

In addition, group I-2 occupancies must be identified as either a Condition 1 or Condition 2.

I-2 Condition 1 includes facilities that provide nursing and medical care but not emergency care, surgery, obstetrics or in-patient stabilization units for psychiatric or detoxification, which includes but is not limited to nursing homes and foster care facilities.

I-2 Condition 2 includes facilities that provide nursing and medical care and can also provide emergency care, surgery, obstetrics or in-patient stabilization units for psychiatric or detoxification, which includes but is not limited to hospitals.

As mentioned above, the same applies here as well. A facility with 5 or less people receiving medical care shall be classified as a Group R-3 occupancy.

Group I-3:

A building or structure used by more than 5 people who are under restraint or security thus are generally incapable of self-preservation due to security measures that are not under the occupants control.

This includes but is not limited to the following examples:

• Correctional centers
• Detention centers
• Jails
• Prerelease centers
• Prisons
• Reformatories

In addition, group I-3 occupancies must be identified as either a Condition 1, 2, 3, 4 or Condition 5. The level of movement within the space designated as one of these conditions can range from free movement to locked exits, from remote-controlled release exits to restricted movement. A description of each one of these conditions can be found here.

Group I-4:

A building or structure that is occupied by more than 5 people of any age who receive custodial care for fewer than 24 hours per day by people other than parents or guardians, relative by blood, marriage or adoption, and in a place other than the home of the person being cared for.

This includes but is not limited to the following examples:

• Adult day care
• Child day care

The code does note however that child day care facilities providing care for more than 5 but not more than 100 children, 2-1/2 years of age or less, shall be classified as Group E where the rooms in which the children are cared for are located on a level of exit discharge serving such rooms and each child care room has an exit door directly to the exterior.

Also it is important to note the following: Rooms or spaces providing such care within places of religious worship during the religious function shall be classified as part of the primary occupancy, a facility with 5 or less people receiving custodial care shall be classified as part of the primary occupancy, and a facility location within a dwelling unit having 5 or less people receiving custodial care shall be classified as a Group R-3 occupancy.

Group M Occupancy – Mercantile

What is a Group M Occupancy?

A Group M occupancy is a use that involves the display and sale of merchandise, stocking of goods, and is accessible to the public.

What Are Examples of a Group M Occupancy?

This includes but is not limited to the following examples:

• Department stores
• Drug stores
• Markets
• Motor fuel-dispensing facilities
• Retail or wholesale stores
• Sales rooms

When certain hazardous materials are stored or displayed in a single control area of a Group M occupancy, they shall not exceed the quantity limits of Table 414.2.5(1) or otherwise it can be classified as a Group H occupancy.

Motor Fuel-Dispensing Facilities

Motor fuel-dispensing facilities are considered special occupancies and are required to comply with Section 406.7.

Group R Occupancy – Residential

What is a Group R Occupancy?

A group R occupancy is a use of a building or structure intended for sleeping purposes when not classified as a Group I or when not regulated by the International Residential Code (IRC).

What Are Examples of a Group R Occupancy?

Group R-1:

The sleeping units in this occupancy group are primarily transient in nature.

This includes but is not limited to the following examples:

• Transient boarding houses with more than 10 occupants
• Transient congregate living facilities with more than 10 occupants
• Transient Hotels
• Transient Motels

Group R-2:

This occupancy group contains sleeping units or more than 2 dwelling units where the occupants are primarily permanent in nature.

This includes but is not limited to the following examples:

• Apartment houses
• Nontransient boarding houses with more than 16 occupants
• Nontransient congregate living facilities with more than 16 occupants
• Convents
• Dormitories
• Fraternities and sororities
• Nontransient hotels
• Live/work units
• Monasteries
• Nontransient motels
• Vacation timeshare properties

Group R-3:

The occupants in this occupancy group are primarily permanent in nature and are not classified as a Group R-1, R-2, R-4 or I.

This includes but is not limited to the following examples:

• Buildings not containing more than 2 dwelling units
• Nontransient boarding houses with 16 or fewer occupants
• Transient boarding houses with 10 or fewer occupants
• Care facilities that provide accommodations for 5 or fewer people receiving care
• Nontransient congregate living facilities with 16 or fewer occupants
• Transient congregate living facilities with 10 or fewer occupants
• Lodging houses with 5 or fewer guest rooms

The code does note that care facilities with 5 or fewer people receiving care within a single-family dwelling is permitted to comply with the International Residential Code (IRC) provided an automatic sprinkler system is installed.

Also owner occupied lodging houses with 5 or fewer guest rooms and 10 or fewer total occupants are permitted to be constructed with the International Residential Code (IRC), provided that an automatic sprinkler system is installed.

Group R-4:

A use for more than 5 people but no more than 16, excluding staff, who reside on a 24 hour basis where the occupants are in a supervised residential environment and receive custodial care.

This includes but is not limited to the following examples:

• Alcohol and drug centers
• Assisted living facilities
• Congregate care facilities
• Group homes
• Halfway houses
• Residential board and care facilities
• Social rehabilitation facilities

Except as otherwise stated elsewhere in the code, Group R-4 occupancies must meet the requirements for construction as for Group R-3. In addition R-4 occupancies must be categorizes as Condition 1 or Condition 2.

R-4 Condition 1 includes buildings where all people receiving custodial care, without any assistance, are capable of responding to an emergency situation to completely egress a building.

R-4 Condition 2 includes buildings in which any person who receives custodial care requires limited verbal or physical assistance when responding to an emergency situation to completely egress a building.

Group S Occupancy – Storage

What is a Group S Occupancy?

A group S occupancy involves a building that is used for storage purposes.

The code does clarify that a space less than 100 square feet used for the purpose of storage and that is accessory to another occupancy shall be classified as part of that occupancy.

What Are Examples of a Group S Occupancy?

Group S-1:

Buildings occupied for storage uses that are not classified as a Group S-2 occupancy. A Group S-1 occupancy is also known as a moderate-hazard storage occupancy.

This includes but is not limited to the storage of the following examples:

• Aerosol products, Levels 2 and 3
• Aircraft hangar (storage and repair)
• Bags: cloth, burlap and paper
• Bamboos and rattan
• Baskets
• Belting: canvas and leather
• Beverages over 16-percent alcohol content
• Books and paper in rolls or packs
• Boots and shoes
• Buttons, including cloth covered, pearl or bone
• Cardboard and cardboard boxes
• Clothing, woolen wearing apparel
• Cordage
• Dry boat storage (indoor)
• Furniture
• Furs
• Glues, mucilage, pastes and size
• Grains
• Horns and combs, other than celluloid
• Leather
• Linoleum
• Lumber
• Motor vehicle repair garages complying with the maximum allowable quantities of hazardous materials specified in Table 307.1(1) (see Section 406.8)
• Photo engravings
• Resilient flooring
• Self-service storage facility (mini-storage)
• Silks
• Soaps
• Sugar
• Tires, bulk storage of
• Tobacco, cigars, cigarettes and snuff
• Upholstery and mattresses
• Wax candles

Group S-2:

Buildings used for the storage or noncombustible materials such as products on wood pallets or in paper cartons, or in paper wrappings. A Group S-2 occupancy is also known as a low-hazard storage occupancy.

This includes but is not limited to the storage of the following examples:

• Asbestos
• Beverages up to and including 16-percent alcohol
• Cement in bags
• Chalk and crayons
• Dairy products in nonwaxed coated paper containers
• Dry cell batteries
• Electrical coils
• Electrical motors
• Empty cans
• Food products
• Foods in noncombustible containers
• Fresh fruits and vegetables in nonplastic trays or containers
• Frozen foods
• Glass
• Glass bottles, empty or filled with noncombustible liquids
• Gypsum board
• Inert pigments
• Ivory
• Meats
• Metal cabinets
• Metal desks with plastic tops and trim
• Metal parts
• Metals
• Mirrors
• Oil-filled and other types of distribution transformers
• Public parking garages, open or enclosed
• Porcelain and pottery
• Stoves
• Talc and soapstones
• Washers and dryers

Aircraft Hangers

Aircraft hangers are considered special occupancies and are required to comply with Section 412.3.

Motor Vehicle Repair Garages

Motor vehicle repair garages are considered special occupancies and are required to comply with Section 406.8.

Public Parking Garages

Public parking garages are considered special occupancies and are required to comply with Section 406.4, 406.5, or 406.6.

Group U Occupancy – Utility and Miscellaneous

What is a Group U Occupancy?

A Group U occupancy involves a building or structure that is used as an accessory or miscellaneous use not classified as any other specific occupancy.

This includes but is not limited to the following examples:

• Agricultural buildings
• Aircraft hangers accessory to a one or two family residence
• Barns
• Carports
• Fences more than 7 feet in height
• Grain silos accessory to a residential occupancy
• Greenhouses
• Livestock shelters
• Private garages
• Retaining walls
• Sheds
• Stables
• Tanks
• Towers

Private Garages and Carports

Private garage and carports are considered special occupancies and are required to comply with Section 406.3.

Residential Aircraft Hangers

Residential aircraft hangers that are accessory to one or two family dwellings are considered special occupancies and are required to comply with Section 412.4.

Summary

This concludes the list of occupancy types as found in Chapter 3 the 2021 International Building Code (IBC).

---

Related Articles to Read:

• How to Calculate Occupant Load | Easily Explained with Examples
• When Are Fire Sprinklers Required?
• 5 Types of Construction Per the IBC Explained

About the Author