Means of Egress and Accessibility Requirements
The three-part egress system
- Exit access (the path from the room to the exit), the exit itself (a protected enclosure or exterior door), and exit discharge (the path to the public way). A defect anywhere breaks the chain.
- Occupant load is computed from function-based factors and the actual floor area; it drives width, number of exits, and fixtures.
- Required egress capacity typically uses about 0.3 inch per occupant for stairways and 0.2 inch per occupant for other components, subject to absolute minimum widths.
- Number, arrangement, and separation of exits: two exits are required in most occupancies once the load reaches the table threshold, and they must be separated by a fraction of the diagonal of the space.
- Travel distance, common path, and dead-end corridors are measured along the actual walking path, not straight-line distance through walls.
Doors and stairs
- Clear width is measured with the door open at 90 degrees, from face of door to stop - not the nominal leaf size.
- Swing direction, panic hardware, opening force, landings, and hardware height all have limits.
- Stairs: riser and tread dimensions, headroom, handrail height and continuity.
Accessibility
- An accessible route must connect site arrival points, entrances, and all accessible spaces; an accessible means of egress is a distinct and additional requirement.
- Clear floor space, reach ranges, operable parts, and signage.
- Alterations trigger path-of-travel upgrades up to a cost proportion, even in existing buildings.
Worked example
A level room holds 120 occupants. Two exits are required. At 0.2 inch per occupant, capacity demands 24 inches - less than a single minimum door - so the minimum clear door width controls, and the exits still must be separated by roughly half the room diagonal.
Traps
- Measuring door width from the leaf rather than the clear opening.
- Treating an accessible route and an accessible means of egress as the same thing.