Construction Supervisor License Practice Exam

What is the minimum required fire door rating in a two-hour rated firewall?

1. ½ hour

2. 1 hour

3. 1½ hours

4. 2 hours

The correct answer is: 1½ hours

In a two-hour rated firewall, the minimum required fire door rating is 1½ hours. This rating ensures that the fire door can withstand a fire for a significant period, allowing occupants to evacuate safely and giving emergency responders time to address the situation. The fire door acts as a barrier, preventing the spread of flames and smoke between compartments, which is crucial in multi-use or occupancy buildings. The specific requirement for a fire door rating being less than the wall rating itself is grounded in fire safety standards, which state that a door in a two-hour wall must be rated to withstand fire for at least 1½ hours. Therefore, the 1½-hour rating reflects a balance between protection needs and practicality, acknowledging that doors are typically more vulnerable than walls due to their construction and design. Having a door rated below 1½ hours would not provide adequate protection when installed in a firewall that has a two-hour rating. It is critical for maintaining the overall fire resistance of the structure and ensuring compliance with building codes and safety regulations.