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Calculating occupant load for life safety

Published on January 1, 2020

Businesses and building owners must ensure that proper life safety measures are taken in their facilities to protect customers and employees. One aspect of life safety involves calculating the occupant load, which, according to the NFPA, is the total number of persons that might occupy a building or portion thereof at any one time. If a facility is occupied by too many people at once, the risk of injury and illness in an emergency increases dramatically. NFPA 101, Life Safety Code outlines the requirements for calculating and posting occupant load information.


Types of occupancies

The first step in calculating the occupant load of a facility is determining the type of occupancy, such as assembly, business, mercantile, etc. The following list includes common occupancies and their definitions according to NFPA 101:

  • Assembly – used for a gathering of 50 or more persons for deliberation, worship, entertainment, eating, drinking, amusement, awaiting transportation, or similar uses
  • Business – used for the transaction of business other than mercantile
  • Day-care – where four of more clients receive care, maintenance, and supervision, by other than their relatives or legal guardians, for less than 25 hours per day
  • Industrial – where products are manufactured or in which processing, assembling, mixing, packaging, finishing, decorating, or repair operations are conducted
  • Mercantile – used for the display and sale of merchandise (restaurants and drinking establishments with an occupant load of fewer than 50 persons should be classified as mercantile occupancies)

Occupant load calculation guidelines

Depending on the type of occupancy, determining the maximum load of a facility can become a little complicated. In these cases, it is recommended that you contact your local Fire Marshal for assistance with determining the occupant load of your business. Below are some general calculation guidelines from NFPA 101 for reference:

  • In areas under 10,000 square feet, the occupant load shall not exceed 1 person per 5 ft²
  • In areas over 10,000 square feet, the occupant load shall not exceed 1 person per 7 ft²
  • The following chart shows specific rules based on occupancy type:

Occupancy type

Space per 1 person

Assembly use

Concentrated use, without fixed seating

7 ft²

Less concentrated use, without fixed seating

15 ft²

Bench-type seating

18 linear inches

Fixed seating

Use number of fixed seats

Kitchens

100 ft²

Business use

Typical business

150 ft²

Day-care use

Typical day-care

35 ft²

Industrial use

Typical industry

100 ft²

Mercantile use

Sales area on street floor

30 ft²

Sales area on two or more street floors

40 ft²

Sales area on floor below street floor

30 ft²

Sales area on floor above street floor

60 ft²

Floors or portions of floors used only for storage, receiving, and shipping, and not open to general public

300 ft²

Posting requirements

Some facilities may be required to post a sign that includes the calculated maximum load so that the information is publicly available. NFPA 101 states that every assembly use-type room not having fixed seats must have the occupant load of the space posted conspicuously near the main exit of the room, and approved signs must be legible and durable. However, local fire codes may also mandate other types of facilities to post a sign as well. Refer to your local Fire Marshal for specific requirements.

For more information, visit https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=101.

Source: NFPA 101, Life Safety Code (National Fire Protection Association 2018)

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