R 408.10696 Towers.

Rule 696. (1) A tower occupied for purposes such as observation or signaling, either an independent structure or on top of a building, shall be permitted with a single stairway or ramp exit if all of the following conditions are met: (a) The tower is of such size as not to be subject to occupancy by more than 25 persons on any 1 floor level. (b) The tower is subject only to occupancy by persons capable of descending the stairway and is not used for living or sleeping purposes. (c) The construction is fire-resistive, non-combustible, or heavy timber, with no quick-burning interior finish. There must be no combustible materials in, under, or in the immediate vicinity of the tower, except as necessary to perform the requirements of occupancy. (2) Stairs must conform to the requirements of this standard, except that for existing towers fire escape type stairs may be used in compliance with General Industry Safety and Health Standard Part 2. “Walking-Working Surfaces,” as referenced in R 408.10606. (3) A tower, such as a forest fire observation tower and a railroad signal tower designed for occupancy by not more than 3 persons employed therein, need not be constructed of fire-resistive, non-combustible material and may be served by ladders instead of stairs in compliance with General Industry Safety and Health Standard Part 2. “Walking-Working Surfaces,” as referenced in R 408.10606.