Rethinking the ‘smokeproof’ enclosure Stair pressurization
systems in high-rise buildings must be properly designed to
avoid creating adverse conditions for egress. Alternate methods
to pressurizing the stair bear further evaluation. Michael J.
Ferreira, PE, and John H. Klote, PE, D.Sc. The current design
standard for protecting stairwells in high-rise buildings is to
provide a “smokeproof” enclosure, using mechanical ventilation
systems or other design alternatives for the purpose of
prohibiting smoke entry into the stairwell. The International
Building Code (IBC) recognizes three specific means for
providing smokeproof enclosures: - Naturally ventilated stair
balconies - Mechanical ventilation of a stair - Vestibule or
stair pressurization. Due to cost and space advantages, the
provision of a stair pressurization system is the most widely
selected design option recognized by the IBC, and has been the
predominant method for protecting stairwells in high-rise
buildings for more than 20 years. Design difficult