Fire partitions must extend from which point upwards to the ceiling?

Fire partitions are critical components in building design, specifically designed to prevent the spread of fire and smoke throughout various sections of a building. These partitions must extend from the finished floor all the way to the underside of the roof sheathing, slab, or deck above, ensuring a continuous barrier without any gaps or openings that could allow fire to travel through.

By extending to any of these points—whether the underside of the floor assembly, the roof sheathing, or the concrete slab—fire partitions can effectively contain fire and smoke within a designated area. This is essential for both safety and compliance with fire codes, which mandate that fire barriers must be continuous to maintain their structural and functional integrity during a fire event.

Since all listed points represent valid upper extensions for fire partitions depending on construction specifics, it reinforces the idea that fire partitions should adequately meet the building code requirements for fire safety. Therefore, the most comprehensive answer here is that fire partitions must extend from the floor upward to the ceiling, regardless of the specific building condition, demonstrating a critical understanding of fire safety standards in the design and inspection of commercial buildings.