Massachusetts Unrestricted Construction Supervisor License Practice Test

What is the minimum required rating of a fire door in a 3-hour fire wall?

1. A. 2 hours

2. B. 3 hours

3. C. 1.5 hours

4. D. 1 hour

The correct answer is: B. 3 hours

The minimum required rating of a fire door in a 3-hour fire wall is indeed 3 hours. This requirement is based on the principle that the fire door must provide the same level of fire resistance as the wall it is installed in to effectively contain or delay the spread of fire. In a situation where a fire wall has a 3-hour fire-resistance rating, the door set into that wall must match or exceed this rating to ensure that it can withstand fire exposure for the same duration. This alignment in ratings is critical for maintaining the structural integrity of the fire barrier and allowing occupants adequate time for evacuation. A fire door with a lower rating, such as 2 hours, 1.5 hours, or 1 hour, would not fulfill the necessary protective requirement in this scenario, potentially compromising safety and increasing fire risk. Thus, the requirement for the door is to be rated at least 3 hours, making it necessary for effective fire protection.