Ontario Building Code Practice Exam

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

1. Labeled with a fire rating

2. Non-combustible materials

3. Continuous from floor to underside of roof sheathing

4. Minimum thickness of 25 mm

The correct answer is: Minimum thickness of 25 mm

A fire-rated duct assembly is a crucial component in maintaining fire safety in commercial buildings. As such, it is important for it to meet certain requirements in order to effectively contain and slow the spread of fire. Options A, B, and C are all necessary requirements for a fire-rated duct assembly, as they ensure that the assembly is properly labeled, made with non-combustible materials, and is continuous from floor to the underside of the roof sheathing. Option D, on the other hand, is not a requirement because the thickness of the assembly may vary depending on the specific building and fire code regulations. A minimum thickness of 25 mm is not a universal requirement for all fire-rated duct assemblies. Therefore, this choice is not essential for meeting the overall purpose and function of a fire-rated duct assembly.