Section 1004.1/Occupant Load Calculation
IBC 1004.1 and Table 1004.1.2 establish how the occupant load is calculated for means of egress design, using floor area and occupant load factors by use.
The occupant load is determined by dividing the floor area (in square feet) assigned to a particular use by the occupant load factor from Table 1004.1.2. Where the actual number of occupants exceeds the calculated occupant load, the actual number must be used. The occupant load drives the number of exits, exit width, plumbing fixture counts, and ventilation rates for the space.
Why this section exists
Means of egress must be designed for the number of occupants who could be in a space during an emergency. The occupant load factors in Table 1004.1.2 represent maximum expected densities for each use type. Assembly spaces (7 sq ft per person for standing) have much higher densities than warehouses (500 sq ft per person) because the egress demand is proportionally higher.
What plan reviewers look for
Plan reviewers verify that the occupant load is shown on the floor plans or in a code analysis for every room or area. They check the occupant load factor against Table 1004.1.2 for the stated use, verify that the correct floor area (gross or net) is used per the table footnotes, and confirm that the occupant load flows correctly into exit calculations.
Common violations
Related IBC requirements
Table 1004.1.2 provides the occupant load factors by use. Section 1005.1uses the occupant load to determine minimum egress width. Section 1006.2uses it to determine the minimum number of exits. The occupant load also feeds into plumbing fixture calculations (IPC Table 403.1) and ventilation requirements (ASHRAE 62.1).