Construction Supervisor License Practice Exam

If a wall has a two-hour fire rating, what is the minimum opening protective assembly rating allowed in hours?

1. 1-1/2

2. 2

3. 1

4. 3

The correct answer is: 1-1/2

When considering the fire rating of a wall, the opening protective assembly (such as doors, windows, or other openings) must be rated to ensure it provides equivalent or greater protection than the wall itself. If a wall has a two-hour fire rating, this establishes how long it can withstand fire before failing. The generally accepted practice is that the rating for the opening protective assembly should be at least equal to the rating of the wall, but standards often allow for a reduction in the protective assembly rating when specific conditions are met, typically recognizing the wall's overall fire resistance. In many jurisdictions, a common approach allows for a minimum rating of one and one-half hours for openings in a two-hour rated wall. Thus, a rating of one and one-half hours for the opening protective assembly provides sufficient protection without being excessively stringent. This ensures that the assembly can reasonably limit fire spread while still factoring in the characteristics of the wall it is part of. The other ratings, such as two, one, or three hours, either exceed the necessary protection or do not meet the required minimum based on typical code allowances for such assemblies in rated walls.