Which type of dampers must be used to protect shaft enclosures that are permitted to be penetrated by ducts and air transfer openings?

The correct answer indicates that both fire dampers and smoke dampers are required to protect shaft enclosures that can be penetrated by ducts and air transfer openings. This is important because these dampers serve different but equally crucial roles in maintaining safety and compliance with building codes.

Fire dampers are designed to close automatically upon detection of heat from a fire, thereby preventing the spread of flames and smoke through duct systems and into shaft enclosures. This is essential in protecting the integrity of the building's fire-resistance-rated assemblies.

Smoke dampers, on the other hand, are specifically aimed at controlling the movement of smoke through duct systems, particularly in the event of a fire. They help manage smoke migration to ensure that hazardous smoke does not spread to other areas of the building, which is vital for occupant safety and evacuation processes.

Using both dampers in these scenarios is critical for providing comprehensive protection. This dual approach ensures that while fire may be contained, the movement and expulsion of smoke can also be effectively controlled, creating a safer environment in commercial buildings.