12.5 Exit Count, Remoteness, Egress Capacity, Travel Distance & Dead Ends

Exit Quantity & Distribution (IBC Section 1006)

Determining the required number of exits occurs at three hierarchical levels: individual rooms, entire stories, and the overall building.

Individual Spaces & Table 1006.2.1

A single exit or exit access doorway is permitted from an individual room or tenant space only when the occupant load and common path of travel do not exceed statutory thresholds:

• Group A (Assembly): Maximum 49 occupants (a 50th occupant triggers mandatory 2 exits).
• Group B (Business): Maximum 49 occupants and 75-foot common path (extended to 100 feet if sprinklered with NFPA 13).
• Group E (Educational): Maximum 49 occupants and 75-foot common path.

Story-Level Exit Minimums (IBC Table 1006.3.2)

Where the occupant load of a story requires multiple exits, the following baseline applies:

• 1 to 500 occupants: Minimum 2 exits.
• 501 to 1,000 occupants: Minimum 3 exits.
• More than 1,000 occupants: Minimum 4 exits.

Convergence of Egress (IBC Section 1005.6)

Where means of egress from stories above and stories below converge at an intermediate level (such as exit stairs from upper floors and basement stairs meeting on the ground floor), the capacity of the means of egress from the point of convergence to the public way must be sized for the sum of the converging occupant loads.

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Arrangement & Remoteness of Exits (The Diagonal Rule)

To ensure that a single localized fire cannot block both paths of egress simultaneously, IBC Section 1007.1.1 enforces the Remoteness Rule:

   ┌────────────────────────────────────────────────────────┐
   │Door 1                                                  │
   │  [X]                                                   │
   │   │                                                    │
   │   │                                                    │
   │   │ < - - - - - - - Overall Diagonal (D) - - - - - - > │
   │   │                                                    │
   │   │                                                    │
   │   │ < - - Minimum Exit Separation - - >                │
   │   │       Non-Sprinklered: D / 2                       │
   │   │       NFPA 13 Sprinklered: D / 3                   │
   │   └──────────────────────────────────────────────[X]───┤
   │                                                 Door 2 │
   └────────────────────────────────────────────────────────┘

The Remoteness Rule Geometry

1. Calculate the overall maximum diagonal dimension ($D$) of the space or building served, measured corner-to-corner in a straight line.
2. Non-Sprinklered Buildings: The minimum straight-line separation distance between the centerlines of the two exit doors must be not less than one-half (1/2) of the maximum diagonal dimension ($D / 2$).
3. Sprinklered Buildings (NFPA 13): In buildings protected throughout with an approved NFPA 13 automatic fire sprinkler system, the minimum separation distance is reduced to not less than one-third (1/3) of the maximum diagonal dimension ($D / 3$).

Where three or more exits are required, at least two exits must meet the 1/2 or 1/3 remoteness rule, and the remaining exits must be arranged a reasonable distance apart so that if one becomes compromised, the others remain fully functional.

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Egress Capacity & Sizing (IBC Section 1005)

Egress components must be sized to accommodate occupant volume without causing dangerous crowd crush or bottlenecks.

Capacity Sizing Factors

Condition: To utilize the reduced factors (0.20 and 0.15 inches), the building must be equipped throughout with an approved NFPA 13 sprinkler system AND an emergency voice/alarm communication system (EVACS) complying with IBC Section 907.5.2.2.

Sizing Example

If a non-sprinklered floor generates an occupant load of 400 persons distributed equally between two exit stairs:

• Occupants per stair = $400 / 2 = 200$ occupants.
• Required stair width = $200 \times 0.30 \text{ in} = 60.0 \text{ inches}$.
• Required door clear width feeding each stair = $200 \times 0.20 \text{ in} = 40.0 \text{ inches}$.

Minimum Nominal Dimensions

Calculated capacity width must never fall below baseline minimum dimensions:

• Corridors: Minimum 44 inches when serving an occupant load $> 50$ (36 inches if $\le 50$; 72 inches in Group E schools serving $> 100$ occupants; 96 inches in Group I-2 hospitals).
• Exit Doors: Minimum clear opening width of 32 inches (measured between door face open at 90 degrees and frame stop). Maximum door leaf width is 48 inches nominal.

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Travel Limits, Common Path, Dead Ends & Hardware

Common Path of Travel vs. Exit Access Travel Distance

• Common Path of Travel: That portion of exit access travel before two separate and distinct paths of egress to two exits become available. In Group B, common path is limited to 75 feet (100 feet if sprinklered). In Group A, it is limited to 75 feet.
• Exit Access Travel Distance (Table 1017.2): The total distance traversed from the most remote point on a floor plate along the natural path of travel to the entrance of an exit. For Group B business occupancies: 200 feet non-sprinklered, increased to 300 feet in NFPA 13 sprinklered buildings.

Dead-End Corridors (IBC Section 1020.4)

A dead-end corridor occurs where an occupant enters a corridor with only one direction of egress travel. Corridors terminating in a dead end cannot exceed 20 feet in length. However, in buildings equipped throughout with an approved NFPA 13 sprinkler system, dead ends are permitted up to 50 feet in Groups B, E, F, I-1, M, R-1, R-2, S, and U.

Door Swings and Panic Hardware

• Door Swing Direction: Exit access doors and exit doors must swing in the direction of egress travel when serving an occupant load of 50 or more persons, or when serving any space classified as High Hazard (Group H).
• Panic Hardware (IBC Section 1010.1.10): Unlatching devices consisting of a crossbar or touchpad extending across not less than half the door leaf width, activating under a maximum unlatching force of 15 pounds-force. Mandatory on all latching doors serving Group A (Assembly) and Group E (Educational) occupancies with an occupant load of 50 or more.