International Building Code 3310.1
Stairways required. Where a building has been constructed
to a height greater than 50 feet (15 240 mm) or four
stories, or where an existing building exceeding 50 feet (15 240
mm)in height is altered, at least one temporary lighted stairway
shall be provided unless one or more of the permanent stairways
are erected as the construction progresses.
International Building Code 3310.2
Maintenance of exits. Required means of egress shall
be maintained at all times during construction, demolition,
remodeling or alterations and additions to any building.
Exception: Approved temporary means of egress systems
International Building Code 3310.3
Stairway floor number signs. Temporary stairway
floor number signs shall be provided in accordance with the
requirements of Section 1020.1.6.