Number of exits and exit separation (½ vs ⅓ diagonal)

One-line orientation

Two egress questions get asked together — how many exits a space needs, and how far apart they must be — and the classic trap is the sprinkler trade-off, which reduces the required diagonal separation from ½ to ⅓.

Key points

• Number of exits:
  • 0–49 occupants: generally 1 exit may serve in common occupancy groups.
  • 50–500 occupants: 2 exits.
  • 501–1,000 occupants: 3 exits.
  • More than 1,000 occupants: 4 exits.
• Exit separation (remoteness): where two exits are required, they must be separated by at least ½ the length of the longest diagonal of the space being served.
• Sprinkler trade-off: in a sprinklered building, the minimum exit separation may reduce from ½ to ⅓ of the longest diagonal. The smaller fraction allows the exits to be closer together.
• Why a diagonal: measuring off the longest diagonal forces the two exits to be genuinely remote, so a single event is unlikely to block both.

Confusions / comparison

	Non-sprinklered	Sprinklered
Required exit separation	≥ ½ of longest diagonal	≥ ⅓ of longest diagonal
Direction of the change	Baseline	Requirement is relaxed (smaller fraction)
Measured from	Longest diagonal of the space	Longest diagonal of the space
Number of exits trigger	Two at 50+ occupants (one-exit cap = 49); 3 above 500, 4 above 1,000	Same occupant-load logic; sprinklers can also extend other distances

Related

→ Means of egress parts (this topic): what an “exit” is that you are counting · Common path vs travel distance vs dead-end (this topic): the other set of egress measurements · Corridors (this topic): width and dead-end limits along the route.