Which of the following is NOT considered a TYPE 1 building layout category?

• A. Atrium
• B. Center hallway
• C. Center core
• D. Combination

Answer: (A)

Type 1 building layout categories describe interior arrangements that organize circulation and access around a central route or core to support predictable egress and fire safety. Center hallway and center core are traditional patterns: a central spine with rooms along a corridor, or a building organized around a centralized vertical core containing stairs and elevators. A combination layout blends elements of these patterns to serve specific functional needs while maintaining controlled egress paths.

An atrium, by contrast, is a large open vertical space that can span multiple floors and disrupt standard egress and smoke-control thinking. It introduces openness and vertical connectivity that don’t fit the typical Type 1 layout patterns, making it not considered a Type 1 layout category.