What is the fire-resistance rating range commonly required for enclosure walls in taller buildings?

• A. 3 or 4 hours
• B. 1/2 to 1 hour
• C. 1 or 2 hours
• D. 3/4 to 1-1/2 hours

Answer: (D)

Fire-resistance rating shows how long a wall can stand up to fire exposure while keeping its integrity. In taller buildings, enclosure walls are placed to confine fire, protect occupants, and keep exit paths clear. The range of 3/4 hour to 1-1/2 hours fits the typical protection level for these enclosure walls most of the time, providing enough time for evacuation and firefighter response without requiring the higher ratings reserved for the most critical barriers. This is why that range is considered the common requirement.