Significant changes to smoke control in atriums in the 2021 International Building Code

A modification to Section 404.5 (Smoke Control in Atriums) in the 2021 International Building Code 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.

Read the full significant change.

The 2021 Significant Changes guides are available for the International Building, Fire, Residential, 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. Each edition provides a comprehensive analysis of significant changes since the 2018 edition, offering key insights into its contents and implications. Each change analysis features the affected code sections and identifies the change with strikethroughs and underlines to show modifications to the existing language. Each change is accompanied by a quick summary, detailed illustrations, and a discussion of its significance, which brings the technical jargon of the code to life in a real-world setting.

Significant Changes to the International Building Code, 2021 Edition is available in the ICC Store or through Digital Codes Premium.