An exit stairway designed and constructed so that movement of the products of combustion produced by a fire into the enclosure is limited describes which feature?

• A. Smoke-Proof Enclosure
• B. Exit Access
• C. Means of Egress
• D. Exit

Answer: (A)

The situation describes a feature whose purpose is to keep the stair enclosure free from smoke so occupants can descend safely during a fire. This is exactly what a smoke-proof enclosure provides: a stairwell or exit shaft designed and constructed to limit the movement of combustion products into the enclosure, often with fire-rated assembly and doors that resist smoke intrusion and, in some buildings, additional smoke-control measures. By preventing smoke from infiltrating the exit path, it helps maintain tenable conditions for people evacuating.

The other terms refer to parts of the egress system rather than a smoke-control feature. Exit access is the path from a space to an exit, means of egress encompasses the entire egress system (exit access, exit, and exit discharge), and an exit is the portion that leads from a building to the exterior or a public way. None of these specifically describe limiting smoke movement into the enclosure.