Significant changes to the 2021 International Building Code
The 2021 Significant Changes guides are available for the International Building, Residential, Fire, Energy Conservation, Plumbing, Mechanical and Fuel Gas Codes. This valuable series can help any code user save time by zeroing in on the most critical changes in the 2021 International Codes. The Code Council’s technical experts provide summaries, analysis and graphics for these changes making them clear and easy to understand.
2021 International Building Code
A modification to Section 404.5 (Smoke Control in Atriums) states that in the evaluation of whether a smoke control system is required for an atrium condition, vertical opening protection consisting of a combination of both the atrium and a shaft enclosure is now recognized.
A major component of the life-safety system for a building containing an atrium is the required smoke control system. Intended to prevent the migration of smoke throughout interconnected stories of a building via the atrium, the design of the smoke control system is to be in accordance with Section 909. The smoke control system is to be installed in all atriums connecting more than two stories as well as those Group I-2 and Group I-1, Condition 2 buildings where atriums connect two or more stories. The extension of an atrium without smoke control beyond two stories has historically been prohibited; however, a new exception removes that limitation where two conditions are met. First, only the two lowest stories are permitted to be open to the atrium.
Second, those stories located above the two lowest stories are required to be separated from the atrium with shaft enclosures having a minimum fire-resistance rating in compliance with Section 713.4. The new allowance recognizes that a combination vertical opening condition consisting of both an atrium and a shaft enclosure provides the necessary degree of separation expected between multiple stories, eliminating the need for a smoke control system.
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