The One-Stair Building

Not as it exists, and certainly not for the renovated floor.

Reasoning:

• Fire escapes are a legacy element. The code recognizes existing fire escapes as a means of egress for existing conditions where the code official finds them adequate - stable attachment, maintained treads and rails, no obstructions, adequate discharge to a public way, and access in a manner the code permits.
• Access through a window is the weak link. Window access is tolerated only under narrow existing-building allowances and is not acceptable where new work is being performed on the floor it serves. A window sill is not a door, and it fails as a compliant exit access path for occupants of a renovated office floor.
• The stair-to-storage conversion is the root problem: a required exit was removed without approval and is now occupied by a restroom. That conversion is an unpermitted alteration that reduced egress capacity for every floor above.

Require restoration of the second enclosed stair or an approved equivalent, and do not approve the Level 2 permit until the building's egress is resolved. The fourth-floor renovation is the trigger to look, but the deficiency is building-wide.

Work through the single-exit allowance rather than declaring the building illegal on sight. A single exit is permitted only where every condition in the applicable single-exit provisions is met: occupancy group, maximum number of stories, maximum occupants per story, and maximum travel distance to the single exit.

Checks:

• Story occupant load on each of floors 2 through 4 (45 each) and on the ground floor, measured rather than assumed, since office build-outs vary considerably.
• Travel distance from the most remote point on each floor to the stair, and the common path of travel, which in an unsprinklered building is short. A 1926 floor plate is usually deep and the remote corner typically fails the travel-distance limit.
• Whether the ground-floor retail and the upper floors share the same exit; the retail's 60 occupants exceed the single-exit ceiling for that story on their own.

Expect the single-exit allowance to fail on travel distance and occupant load. The right output is not an immediate vacate but a written finding with measurements, an interim fire watch or reduced occupancy if warranted, and a compliance schedule to restore or add a second exit.

Width. Required stair width is 0.3 inch per occupant. Determine the occupant load the stair must serve - typically the total building population assigned to that stair, which for a single stair is everyone above the ground floor. With roughly 135 occupants on floors 2 through 4, the minimum is about 41 inches, so 44 inches may pass on width alone. If the ground-floor occupants also discharge through this stair, the load rises to about 195 and the requirement becomes roughly 59 inches - the stair fails. The calculation, not the tape measure alone, decides the question.

Door swing. Compare against the door provisions: doors serving occupant loads at or above the threshold (50 occupants) must swing in the direction of egress travel, and a door swinging into a stair enclosure or its landing may not reduce the required width of the landing or stair below its minimum. Measure the clear landing depth with the door at 90 degrees. A door that eats the landing at the second floor creates a pile-up point at the worst possible location - the level of exit discharge is where two directions of travel converge.

Both findings belong in the same report as capacity issues, because they compound: a narrow stair with a blocked landing functions worse than either defect alone.