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Occupant Load and Means of Egress Sizing — IBC Chapter 10 (2021)

Occupant load per space from Table 1004.5, egress capacity of stairways and other components (§1005.3), minimum number of exits, minimum widths and the 50 % loss-of-one-exit check (§1005.5).

Spaces on the story

One space per line: function (exactly as in the list below), area (ft²) — gross or net as the table specifies

Table 1004.5 functions (choose to append a line)

Occupancy group

Provided stairway widths (in), comma separated

Sprinklered throughout (903.3.1.1 or 903.3.1.2)
Emergency voice/alarm communication system (907.5.2.2)

Results

Occupant load of the story—

Space	Area (ft²)	Factor	Occupants

Capacity factors (stairs · other)—

Required stair width · other components—

Minimum exits · min stair / corridor / door—

Provided stairs: total · count · 50 % loss check—

IBC 2021Table 1004.5 and §1004.5.1 verbatim from the state-adopted text (Washington WAC 51-54A-1004, effective 2024-03-15; IFC Chapter 10 = IBC Chapter 10). §1005.3 capacity factors and the sprinkler + voice/alarm reduction; §1005.5. Exits per story, minimum stair/corridor widths and the 32 in door width: consistent secondary sources.

VerifiedHand calculations and published worked examples (4 500 ft² office → 30; 480 occupants → 144 in of stairs; 84 + 60 in fails the 50 % rule). Business areas were 100 gross before the 2018 IBC; mercantile is a single 60 gross factor — older "30 grade floor / 60 upper floors" splits are obsolete.

Preliminary calculation tool. Final design requires the full text of the referenced standard (see the sources on this page) and review by a licensed PE.