Ducts shall not pass through which barrier?

• A. smoke barriers
• B. fire walls
• C. sprinkler cabinets
• D. floor slabs

Answer: (B)

Ducts should not pass through fire walls because those walls are built to electrically separate and contain a fire between areas of a building. A duct penetrating a fire wall creates a potential pathway for flames and smoke to cross the barrier, undermining the wall’s intended fire-resistance. In practice, if a duct must traverse a fire wall, it must use a listed fire-rated penetration system with proper dampers and firestopping to maintain the wall’s rating. Other barriers differ in purpose and may allow penetrations with the correct rated assemblies, but the blanket prohibition applies to fire walls to preserve compartmentation and occupant safety.