412.3.2 Stairways.
BC § 412.3.2
Stairways in airport traffic control towers shall be in accordance with Section 1011. Stairways in airport traffic control towers are not required to comply with Section 1011.12. Stairways shall be smokeproof enclosures complying with one of the alternatives provided in Section 909.20. The stairway shall be separated from elevators by a minimum distance of one-half of the diagonal of the area served measured in a straight line. Exception: The stairway and elevator hoistway are permitted to be located in the same shaft enclosure without the minimum separation distance, provided they are separated from each other by a 4-hour fire barrier having no openings. Such stairway shall be pressurized to a minimum of 0.15 inch of water column (43 Pa) and a maximum of 0.35 inch of water column (101 Pa) in the shaft relative to the building with stairway doors closed.
