Ontario Building Code Practice Exam 2024 - Free Building Code Practice Questions and Study Guide

A fire-rated ceiling assembly must meet the requirements of non-combustible materials, being labeled with a fire rating, and being continuous from wall to wall. This means that all options regarding the type of materials, labeling and continuity must be met in order for a ceiling assembly to be considered fire-rated. A minimum thickness of 50 mm, on the other hand, is not a specific requirement for a fire-rated ceiling assembly. It may be a recommended thickness for added fire resistance, but it is not a mandatory requirement. Therefore, option D is not a requirement for a fire-rated ceiling assembly in a commercial building.