Which assembly should not have open spaces extending under or through permanent partitions or walls?

The reasoning behind selecting fire resistance floor assembly is rooted in safety and building code compliance. Fire resistance assemblies are designed to contain fires, prevent them from spreading, and maintain structural integrity during a fire event. When there are open spaces extending under or through these assemblies, it can compromise their effectiveness. Such openings can allow smoke and flames to travel unimpeded, which could lead to increased fire spread and greater risk to occupants and emergency responders.

Other assemblies may have different requirements and tolerances for open spaces due to factors like structural support or insulation, which do not carry the same critical implications for fire containment. Therefore, maintaining a fully sealed and contiguous fire resistance floor assembly is essential to uphold its intended purpose and ensure safety within the building.