What contributes to the fire rating in a protected stairwell?

What contributes to the fire rating in a protected stairwell?

• A. Fire department response time
• B. Occupancy
• C. Stairwell width
• D. Building age

Answer: (B)

Occupancy determines the fire rating for a protected stairwell because the required level of fire resistance is set to match how the space will be used and how many people it must serve during an evacuation. Different occupancy types have different risk profiles and evacuation times, so codes specify higher fire-resistance ratings for stairs serving spaces with more occupants or more complex egress needs to ensure people can exit safely if a fire occurs. The stairwell must maintain its integrity long enough for occupants to reach a safe area, which is why occupancy is the key factor driving the rating. The other options don’t set the rating itself: response time is about external emergency services, stairwell width affects how quickly people can move but not the inherent fire resistance duration, and building age may influence construction details but does not determine the required fire-resistance rating based on life-safety needs.

Occupancy determines the fire rating for a protected stairwell because the required level of fire resistance is set to match how the space will be used and how many people it must serve during an evacuation. Different occupancy types have different risk profiles and evacuation times, so codes specify higher fire-resistance ratings for stairs serving spaces with more occupants or more complex egress needs to ensure people can exit safely if a fire occurs. The stairwell must maintain its integrity long enough for occupants to reach a safe area, which is why occupancy is the key factor driving the rating.

The other options don’t set the rating itself: response time is about external emergency services, stairwell width affects how quickly people can move but not the inherent fire resistance duration, and building age may influence construction details but does not determine the required fire-resistance rating based on life-safety needs.