Occupancy Classifications and Loads

You must always determine the occupancy classification and the occupancy load to establish the parameters that are to be used for your project.

An occupancy classification is assigned to the building or space. It is a broad classification. (educational)Building type is more specific. It is a specific class or category within an occupancy. (high school)

The number of people or occupants for which the code will require you to provide means of egress or exiting in your design.The occupant load sets the minimum level of exiting that must be providedNumber of exitsWidths of corridorsDistance to nearest exit

The maximum number that can occupy the space.An older term used by the older codes.

Must be assigned to the building or to a space within the buildingOne of the most important steps in the code processShould be the first thing you determine when designing an interior

Will affect code requirement pertaining to:Occupant loadMeans of egressEgress capacitiesFinish selectionNumber of plumbing fixturesAs well as other areas (shown in fig. 2.1, page 58)

Existing buildings are already determinedBuildings with different types of tenants require that occupancy classifications be determined for each tenant.Careful attention to renovation work (ie: a warehouse converting to apartments)Have a code official approve your decision if you are unsure

The ten most common occupancies are:AssemblyBusinessEducationalFactory or IndustrialHazardousInstitutionalMercantileResidentialStorageUtility and Misc.

You will need to know three things before you can accurately determine the occupancy classificationThe type of activity occurringThe expected number of occupants andIf any unusual hazards are present These factors can affect the classification of a building type. (ie: if a particular building is planned to serve a large number of people, it may be classified as an Assembly)

Unusual hazards can either change an occupancy to a stricter classification or simply require all or part of a building to be classified as a Hazardous occupancysubject to tougher codes. (page 61)Large groups of peopleNight occupanciesMobility of occupantsFamiliarity of occupantsPotential spread of fire

Refer to pages 63-83

Whether an occupancy is new or existing becomes important when using the LSC.An occupancy is considered new if it falls in the following categories:New constructionRelocation into an existing buildingNew addition to an existing buildingOccupancy is staying in existing space, but changing size or use

Incidental Use (page 88) (hazardous areas that are relatively small, storage, furnace rooms, boiler rooms, laundry rooms etc.) Additional fire and smoke protection may be required.Accessory Occupancy (page 89) A smaller occupancy that is typically less than 10% of the total area of the floor on which it is located. Mercantile (M) with design center (B) can be considered as an accessory and not have to design using two occupancy requirements

Mixed Occupancies: When two or more occupancies occur in the same building - under one roof. (Hotels with restaurants, ballrooms, exercise rooms will be both Assembly and Business)Trend for the futureDifferent codes will apply to eachRequires fire-walls between spacesTreat as its own entityOffice building with a childcare center (Business/Educational)Hospitals with cafeterias (Institutional/Assembly)Malls with food courts (mercantile/assembly)

Certain occupancy classifications are also affected by the ADA. (page 95)Federal building and 1 and 2 family dwelling are not regulated by the ADA.Restaurants and Cafeterias (Assembly)Libraries (business or educational)Mercantile and many businesses Medical (healthcare)Transient lodging (residential and correctional/detention)Childcare

An occupant load is the second thing you need to determine at the beginning of a project.It sets the minimum number of occupants for which you must design the means of egress from a building or specific area.Each code set a predetermined amount of space or sq. ft for each occupant. This figure is called the load factor.

The load factor is used to help you determine the occupant load for a space or a building.The load factor will help to determine the number of people that will be using the corridors, stairs and exits in the event of a fireSee table on page 101.

This factor indicates the amount of space or area it is assumed each person present will requireAlthough the sq foot figures may seem high for one person, they allow for furniture and equipment and in some cases corridors, closets and other miscellaneous areas.It is always represented in sq. feet; however, it can be a gross or a net figure.

The gross area refers to the building as a whole and includes all misc. spaces within the exterior walls. The net area refers to actual occupied spaces and does not include accessory spaces such as corridors, restrooms, utility closets etc.When net figures are required, it is assumed that the occupants who are using an ancillary area would have left the occupied space to do so. (ex: a student walking in a hallway would already have been counted as a student in the classroom)Note: a Load factor has nothing to do with individual space allocation with planning a facility.

Occupancy Load = Floor Area (sq. ft) / Occupant Factor

Even if you know that your client will have fewer occupants, you must plan the space based on the determined load figures as required by the codes.

You must figure each occupant load separatelyExample: Multistory buildings may have mercantile, business on one floor. Figure each occupancy type for each floor and add them together

Example wasTemple Baptist Church prior to construction of new sanctuary:Worship hall is also a basketball courtFellowship hall is also cafeteriaFigure the occupancy load based on the largest concentration of people.

Common in Assembly occupanciesThe seats are considered fixed if they do not easily move.TheatersChurchesStadiums, bleachersDo not use standard formulaCount actual seatsFor seats without arms, figure 18 for each occupant12 pew is 144 divided by 18 = 8 people

The occupant load that you determine in the beginning of a project will be used again later in your code research to determine the means of egress, such asThe number of exitsWidth of exitsPlacement of exits

Every assembly room or Assembly occupancy usually requires the approved occupant load to be permanently posted near the main exit from the space. A typical sign might readOccupancy by more than 100 persons is dangerous and unlawful.

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