Occupant Safety and Accessibility: Egress and Usable Routes
Egress as a system
The egress chapter is the most heavily tested area of any large-building code. Learn the components in order: exit access (the path from any point to an exit), the exit itself (enclosed stairs, ramps, exit passageways, exterior doors at grade), and exit discharge (the path from the exit to the public way). Every egress question asks you to identify which component is at issue, then apply the rules for that component: number of exits, remoteness, width, travel distance, dead ends, common path, and capacity.
Capacity and accessibility
Occupant load is computed from the code's area-per-occupant factors and drives egress width, number of exits, and plumbing fixture counts. Egress width is expressed per occupant and per story, and capacity must never decrease in the direction of travel. Accessibility concepts include accessible routes, accessible means of egress, areas of refuge, and the requirement that accessible routes connect to the public way.
Traps
- Using the wrong occupant-load factor for a mixed space, or forgetting to use the larger of calculated and actual counts.
- Missing that two exits must be remote from each other by a defined distance.
- Assuming an area of refuge is optional where the building is sprinklered; the code's conditions control.
- Forgetting that doors must swing in the direction of egress travel for high-occupancy spaces.
Rule of thumb
Compute occupant load first using the exact factor for the use; then check exits, remoteness, width, and travel distance in that order. Most wrong answers come from a bad occupant load.
Worked example
A 400 m² assembly space at a factor of 1.5 m² per occupant yields roughly 267 occupants; that number sets the required egress width and the number of exits. If a proposed layout provides only one exit, the answer is almost always that an additional remote exit is required.