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Chapter 2 Occupancy Classifications and Loads
The first step You must always determine the occupancy classification and the occupancy load to establish the parameters that are to be used for your project.
Building Type vs. Occupancy 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)
Occupant Load 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 provided Number of exits Widths of corridors Distance to nearest exit
Occupant Content The maximum number that can occupy the space. An older term used by the older codes.
Occupancy Classifications Must be assigned to the building or to a space within the building One of the most important steps in the code process Should be the first thing you determine when designing an interior
Occupancy Classification Will affect code requirement pertaining to: Occupant load Means of egress Egress capacities Finish selection Number of plumbing fixtures As well as other areas (shown in fig. 2. 1, page 58)
Determining Occupancy Classifications Existing buildings are already determined Buildings 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
Determining Classifications The ten most common occupancies are: Assembly Business Educational Factory or Industrial Hazardous Institutional Mercantile Residential Storage Utility and Misc.
Determining Classification You will need to know three things before you can accurately determine the occupancy classification The type of activity occurring The expected number of occupants and If 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)
Hazards 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 occupancy…subject to tougher codes. (page 61) Large groups of people Night occupancies Mobility of occupants Familiarity of occupants Potential spread of fire
List of Occupancies Refer to pages 63 -83
New vs. Existing 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 construction Relocation into an existing building New addition to an existing building Occupancy is staying in existing space, but changing size or use
Other considerations 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 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 future Different codes will apply to each Requires fire-walls between spaces Treat as its own entity Office building with a childcare center (Business/Educational) Hospitals with cafeterias (Institutional/Assembly) Malls with food courts (mercantile/assembly)
ADA Regulations 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
Occupant Loads 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.
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 fire See table on page 101.
Load Factor This factor indicates the amount of space or area it is assumed each person present will require Although 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.
Gross vs. Net 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.
The formula page 102 Occupancy Load = Floor Area (sq. ft) / Occupant Factor
Important note… 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.
Mixed Used or Occupancies You must figure each occupant load separately Example: Multistory buildings may have mercantile, business on one floor. Figure each occupancy type for each floor and add them together
Multiple Use Example was. Temple Baptist Church prior to construction of new sanctuary: Worship hall is also a basketball court Fellowship hall is also cafeteria Figure the occupancy load based on the largest concentration of people.
Fixed Seats Common in Assembly occupancies The seats are considered fixed if they do not easily move. Theaters Churches Stadiums, bleachers Do not use standard formula Count actual seats For seats without arms, figure 18” for each occupant 12’ pew is 144” divided by 18 = 8 people
Means of Egress 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 as The number of exits Width of exits Placement of exits
Final Note 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 read “Occupancy by more than 100 persons is dangerous and unlawful. ”