IBC - Determining Occupant Load

How are the means of egress requirements determined

Occupancy type and load

What is Occupant Load

The maximum number of people for which the means of egress of a building or portion thereof is designed

Occupant Area

OA = NSF + circulation sf (primary and secondary) + incidental space (columns, etc.)The total portion of a building being "actively used by a tenant

How is the occupant load determined for one space with multiple different functions

Floor area of each function is calculated independently and added together

How is the occupant load for a building or floor containing multiple occupancies determined?

Occupancy is determined per room, and added together

What is the difference between occupancy classification and type?

Occupancy classification refers to the entire buildingOccupancy type refers to a specific space

What is an accessory occupancy?

A space or room that is ancillary to a main occupancy but that does not exceed 10% of the floor area of the story in which it is located - Still considered under the classification of the main occupancy

What are examples of accessory occupancies?

-Religious educational and religious auditoriums with OL < 100 = -Assembly OL < 50 People = Group B

Assembly (Definition)

Space used when people gather together

Space has occupancy of less than 50 people or 750sf and is accessory to another occupancy

Classified as a B occupancy

Assembly A-1 (two examples)

Assembly with fixed seating (movie theater, concert hall, radio studio w/ audience)

Assembly A-2 (two examples)

Assembly for food and drink consumption (restaurants, cafeterias and associated commercial kitchens, bars, casinos, clubs, banquet hall)

Assembly A-3 (two examples)

Assembly for worship, recreation or amusement (arcade, art, courtroom, funeral, greenhouse, indoor pool, library, lecture hall, museums, transportation waiting terminals)

Assembly A-4 (two examples)

Assembly for viewing of INDOOR sports events with spectator seating (arena, skating rinks, swimming pools, tennis courts)

Assembly A-5 (two examples)

Assembly for viewing of OUTDOOR sports events with spectator seating (Bleachers, grandstand, stadium)

Assembly, w/ fixed seating and aisles

Occupant load determined by number of seats installed

Assembly waiting spaces

1 person per 7sf

Assembly, w/o fixed seating (concentrated/chairs only)

7 net

Assembly, w/o fixed seating (unconcentrated/ tables and chairs)

15 net

Business Group (Definition; 2 Examples)

Space used for office, professional or service-type transactions, and/or storage of records and accounts (Office, bank, salon, outpatient clinic, dry cleaning and laundry, edu for above 12th grade, research lab, kitchens w/o an associated restaurant)

Business Occupant Load

150 sf per person

Concentrated Business Use

Occupant Load decided by Building Official of AHJNo less than 50sf per occupant (Formula: Total SF/50 = # of people)

Education Group E (Definition)

A space used for educational purposes of six or more people for those 12th grade and under.

Religious educational spaces with OL of less than 100 people per room/space

Group A-3

Day care facilities caring for 5 children or less

Classified as part of the primary occupancy

Dwelling unit providing day care to 5 children or less

Group R-3

Factory Group F (Definition)

Spaces used for assembling, disassembling, fabricating, finishing, manufacturing, packing, or repairing that aren't classified as hazardous or storage

Moderate hazard factory industrial, Group F-1

Factory industrial centers that are of moderate hazard (not identified as F-2)

Low-hazard factory industrial, Group F-2

Factory industrial uses that involve fabrication of NON-combustible materials that don't involve a significant fire hazard

High Hazard Group H (Definition)

Space that involves manufacturing, processing, generation or storage of materials that constitute a physical or health hazard in quantities of excess

Institutional Group I (Definition)

A building which provides care to people who aren't capable of self-preservation without physical assistance, or are detained for correctional purposes under physical restraint

Institutional I-1 (2 examples)

16 or more people (excludes staff) who remain on-site on a 24 hour basis and receive supervision and custodial care (alcohol and drug centers, assisted living, group homes)

Institutional I-2 (2 examples)

Spaces used for medical care on a 24-hour basis for 5 or more people who are incapable of self-preservation (foster care facilities, detox facilities, hospitals, nursing homes, psychiatric hospitals)

Does institutional I-2 provide the following: emergency care, surgery, obstetrics or stabilization


Institutional I-3 (2 examples)

Spaces inhabited by 5 or more people who are under restraint or security and who are incapable of self-preservation (correctional and detention centers, jails and prisons)

Institutional I-4 (2 examples)

Spaces occupied by 5 or more people who receive custodial care less than 24 hours per day, regardless of age (adult and/or child day care)

What is a child day care facility caring for 5 or more but less than 100 children located on a level of discharge with an exit leading directly to the exterior classified as?

Educational Group E

What is a facility that provides custodial care to 5 or fewer people classified as?

Classified as the primary occupancy

What is a facility that provides custodial care to 5 or fewer people in a dwelling unit classified as?

Residential R-3

Mercantile Group M (Definition)

Any retail or wholesale store and sale rooms

Residential Group R (Definition)

Spaces used for sleeping that aren't classified as Group IGroup R-1, R-2, R-3, R-4

Residential R-1 (2 examples)

Contains sleeping units primarily transient in nature (boarding houses w/ 10+ occupants, transient hotels and motels)

Residential R-2 (2 examples)

Contains sleeping units or 2 or more dwelling units that are permanent in nature (apartments, live/work units, non-transient hotels and motels, timeshare properties)

Residential R-3 (2 examples)

Contains permanent dwelling units not classified as R-1, R-2, R-4 (buildings w/o more than 2 dwelling units, congregate living facilities like frats both transient < 16 people and non-transient < 10 people)

Residential R-4 (2 examples)

Spaces with >5 but <16, excluding staff, who reside on a 24-hour basis in a supervised environment receiving custodial care (alcohol and drug centers, assisted living facilities, halfway houses)

Storage Group S

Spaces used for storage of non-hazardous itemsGroup S-1, S-2

Storage S-1

Moderate hazard storage for combustible materials

Storage S-2

Low hazard storage for NON-combustible materials

Utility And Misc Group U


When are two egress doors required

When the occupancy load is more than 50 AND the travel distance is more than 75ft

Incidental space

Areas not occupied by clients (closets, structural columns, walls, etc.) but are required to create the overall space plan.