What is a combination of a fire door, a frame, hardware, and other accessories installed on a horizontal plane that provides fire protection?

The term that describes a combination of a fire door, a frame, hardware, and other accessories installed on a horizontal plane to provide fire protection is a floor fire door assembly. This type of assembly is specifically designed to separate different areas within a building, preventing the spread of fire and smoke between floors. It serves a critical function in maintaining the integrity of fire-rated floor assemblies and allows for safe egress through the building in case of a fire event.

In contrast, a firestop refers to materials used to seal openings and joints in fire-rated walls or floors, thus helping to prevent the passage of flames and smoke. A fire barrier is a construction feature that can also provide fire resistance but is generally vertical in nature, as opposed to being a component like a floor fire door assembly which is indeed installed horizontally. The F rating indicates the duration for which a fire door or assembly can withstand a fire, but it does not denote the entire assembly itself. Therefore, the floor fire door assembly is the most accurate term for the described combination and function in fire protection contexts.