Atriums and open shafts connecting two or more stories are permitted if they are provided with adequate smoke control, automatic sprinkler system protection, and which of the following?

• A. Fire doors
• B. Smoke vents
• C. Fire barriers
• D. Firestops

Answer: (C)

Open vertical openings like atriums and open shafts must be kept from becoming superhighways for fire and smoke. The way this is achieved is by creating a continuous, fire-resistance–rated barrier that partitions the opening between floors, limiting flame and smoke spread. When you add adequate smoke control and an automatic sprinkler system, the fire barrier provides the necessary containment so a fire on one level doesn’t instantly engulf others.

Fire barriers are the required element here because they establish the physical separation that confines fire within a defined area and prevent rapid vertical progression. Fire doors and other features may be part of the barrier system, but they don’t by themselves provide the mandated separation. Smoke vents aren’t the necessary component for this requirement, and firestops address hidden penetrations rather than the overall vertical compartmentalization.