A three-story building's protected stairway enclosure minimum fire rating is?

• A. Two hours
• B. One hour
• C. Three hours
• D. Four hours

Answer: (B)

The main idea is that protected stairways must have a fire-resistance rating that keeps the exit path usable during a fire. For a three-story building, the minimum rating required for the stair enclosure is one hour. This level of rating helps ensure the stairwell remains tenable long enough for occupants on upper floors to evacuate and for responders to access the building, without requiring the more stringent protection needed in taller or more hazardous structures. Higher-rise or more demanding buildings often need longer ratings (two hours or more), while much simpler or smaller structures typically don’t require more than one hour. So, one hour is the appropriate minimum for this scenario.