Which of the following major occupancies does Part 3 apply to?

Part 3 of the Building Code deals specifically with the requirements for buildings that accommodate occupants at higher risk due to their use and nature. Among the major occupancies, Group B, which encompasses care, treatment, or detention facilities, is characterized by its occupancy type that often includes hospitals, nursing homes, and correctional facilities. These types of buildings typically have more stringent safety measures due to the vulnerabilities of their occupants, necessitating the detailed requirements set forth in Part 3.

For different occupancy groups such as Group D (business and personal services), Group C (residential), and Group E (mercantile), the requirements tend to be less strict since the associated risks do not match those found in Group B. These other groups generally have more liberal guidelines under Part 9, which allows for safer but less complex construction practices. Thus, the focus of Part 3 is rightly placed on Group B to ensure a high standard of safety and functionality for these sensitive environments.