Which type of occupancy requires a 4-hour fire resistance rating for barrier assemblies?

The requirement for a 4-hour fire resistance rating for barrier assemblies is applicable to Group H-1 occupancies. These occupancies are classified as high-hazard industrial facilities that handle materials which can present significant fire and explosion risks. The 4-hour rating is crucial in these cases to ensure that there is a robust level of fire protection, allowing adequate time for occupants to evacuate safely and for fire response teams to manage the situation effectively.

In contrast, other groups such as Group A (assembly), Group F-1 (factory), and Group B (business) do not require such stringent fire resistance ratings for their barrier assemblies. Each occupancy type is defined by the nature of its activities, the materials used, and associated risks, dictating different levels of fire protection based on the potential for hazard. Thus, Group H-1's specific needs lead to the requirement of a 4-hour fire resistance rating to mitigate the risk of catastrophic incidents within these high-hazard environments.