Corridors: width, dead-ends, fire rating, door swing

One-line orientation

Corridor questions focus on width, dead-end length, fire rating, and door-swing intrusion. The minimum width increases when the corridor serves 50 or more occupants.

Key points

• Width: minimum 36 in when serving ≤49 occupants; steps up to 44 in when serving 50 or more occupants. The trigger is the occupant count served.
• Ceiling height: minimum 7’-6” along the means of egress; protruding objects (localized soffits/ducts/lights) may reduce headroom to 80” (6’-8”) over no more than 50% of the ceiling area.
• Fire protection: where corridors are required to be rated, they need continuous fire-rated walls, floors, and ceilings — the rated assembly must be unbroken.
• Dead-end limit: a dead-end corridor is capped at 20 ft — extended to 50 ft in many sprinklered occupancies.
• Door swing: a door, at full swing, may not block more than half the required corridor width — and egress doors swing in the direction of travel.

Confusions / comparison

Corridor rule	Threshold / value	What triggers it
Minimum width	36 in (≤49 occ) → 44 in (50+ occ)	Number of occupants served
Ceiling height	7’-6”; 80” (6’-8”) protrusions over ≤ 50% of the area	Localized soffits/ducts only
Dead-end length	20 ft (50 ft sprinklered, most groups)	Corridor with one way out
Door swing intrusion	≤ ½ of required width	A door opening into the corridor
Fire rating	Continuous rated walls/floors/ceilings	Where the corridor is required to be rated

Related

→ Common path vs travel distance vs dead-end (this topic): the dead-end limit measured here · Means of egress parts (this topic): the corridor as the exit-access leg · Number of exits and exit separation (this topic): how the corridor connects required exits.