What must ducts that penetrate non-fire-resistance rated floor assemblies be protected by?

Ducts that penetrate non-fire-resistance rated floor assemblies must be protected by a shaft enclosure to ensure the safety and integrity of the building's fire protection systems. A shaft enclosure serves multiple purposes; it acts as a barrier that can help limit the spread of smoke and fire between floors in a building. This is particularly crucial in non-fire-resistance rated assemblies, where the potential for fire spread through openings poses a significant risk.

The use of a shaft enclosure not only complies with safety regulations but helps in maintaining the intended performance of the building's fire-rated assemblies, providing vital time for occupants to evacuate and for emergency responders to intervene effectively. By containing any potential fire or smoke routes within a defined area, shaft enclosures enhance overall safety in multi-story buildings.