Which of the following is NOT included in a complete through penetration firestop system?

A complete through penetration firestop system is designed to prevent the passage of fire and smoke through openings created by penetrating items such as pipes, cables, or ducts. For such a system to be effective, it typically includes several key components.

The backing material is crucial as it supports the firestop sealant and ensures a complete and secure fit around the penetrating item. The penetrating item is necessary because it is the object that creates the gap in the fire-resistance rated assembly, and therefore must be addressed in the firestop system. The fire-resistance rated assembly itself is foundational, as it is the structure that needs to maintain its integrity during a fire.

Since all the components are indeed essential for a complete through penetration firestop system, the statement that none of them are excluded from the system is accurate. Each element plays a vital role in ensuring the assembly can withstand fire and maintain safety.