What fire-resistance rating is required for separating walls in Group H-2 occupancy?

For Group H-2 occupancies, which consist of facilities that handle flammable or explosive materials (such as certain chemical manufacturing or processing plants), a higher level of fire-resistance is required. This is due to the potential hazards associated with the materials stored or used in these facilities.

The code mandates that separating walls between spaces that contain such hazardous materials must have a fire-resistance rating of at least four hours. This extended rating is crucial to prevent the spread of fire from one area to another, thus enhancing safety and minimizing potential damage during a fire incident. The walls must be robust enough to contain flames and heat for a substantial duration, allowing time for evacuation and emergency response.

In contrast, lower fire-resistance ratings like one hour or two hours may be suitable for other occupancy types or less hazardous conditions but do not meet the stringent requirements for Group H-2 due to the elevated risk associated with the materials involved. Hence, the four-hour rating is the proper and safe choice for these environments.