How should duct systems protected when penetrating nonfire resistance rated floor assemblies?

When duct systems penetrate non-fire-resistant floor assemblies, it is important to ensure that these openings do not compromise the overall fire safety of the building. A shaft enclosure serves as a critical barrier that helps to contain smoke and fire within designated areas, preventing the spread to other parts of the structure. This is in accordance with building codes, which are designed to promote safety and protect occupants during a fire emergency.

A properly constructed shaft enclosure provides not only structural integrity but also fire resistance, which is essential in a multi-story building where ducts may span multiple floors. Utilizing a shaft enclosure aligns with established safety standards and helps maintain the necessary level of compartmentalization in a building to enhance fire safety.

Other approaches, such as using fire dampers, wrapping ducts in noncombustible materials, or simply applying a layer of drywall, may not provide the same level of protection and integrity as a shaft enclosure, which is specifically intended for this purpose. Thus, the correct answer reflects compliance with fire safety regulations that govern the design and installation of duct systems in buildings.