What is the minimum damper rating for penetrations of less than 3-hour fire-resistance-rated assemblies?

The minimum damper rating for penetrations of less than 3-hour fire-resistance-rated assemblies is 1.5 hours. This requirement is established to ensure that fire dampers are capable of providing the necessary fire resistance to maintain the integrity of fire-rated barriers. A fire-resistance-rated assembly acts as a protective barrier, and it is crucial that any openings or penetrations through these barriers are adequately protected.

In this context, a damper rated for 1.5 hours is designed to withstand fire conditions and prevent the spread of flames and smoke, thereby enhancing safety within a building. The rating indicates the duration for which the damper can function effectively in the event of a fire, ensuring compliance with safety codes and protecting the structure and occupants. Keeping it below the 3-hour threshold aligns with the standards that regulate the integrity of fire-resistance-rated assemblies, allowing for appropriate classifications and installations.