Ontario Building Code Practice Exam

Which of the following is not a requirement for a fire-rated roof assembly in a commercial building?

1. Non-combustible materials

2. Labeled with a fire rating

3. Continuous from wall to wall

4. Minimum thickness of 50 mm

The correct answer is: Minimum thickness of 50 mm

A fire-rated roof assembly in a commercial building must have non-combustible materials, be labeled with a fire rating, and be continuous from wall to wall. However, a minimum thickness of 50 mm is not a requirement for a fire-rated roof assembly. This is because the thickness of the materials used in the roof assembly does not directly affect its ability to resist fire. Instead, the materials themselves and the construction method are the key factors in determining a roof assembly's fire rating. Therefore, option D is the correct answer as it is not a requirement for a fire-rated roof assembly.