Where a building being constructed reaches a height greater than 50 feet (15 240 mm) or four stories, or where an existing unoccupied 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 or maintained as the construction progresses. Demolition work shall comply with item 6 of 3306.9.9.
The maximum distance between the working deck of such a building under construction or alteration and the highest floor accessible to a temporary or permanent stair shall be no more than 40 feet or 4 floors. In concrete construction, the working deck is the floor being formed. In steel construction the working deck is the floor where the metal decking and steel components are being placed before concrete is poured.