What characterizes a mechanical firestop system?

A mechanical firestop system is characterized by its use of elastomeric materials, which are flexible and provide a seal against fire and smoke. These materials can expand and contract, effectively sealing gaps around penetrations in fire-rated assemblies. The flexibility of elastomeric materials allows for a reliable barrier that can maintain its integrity even when subjected to the thermal movement of building materials or in the presence of fire.

In contrast, options outlining the use of rigid materials or substances that become inflexible under heat do not align with the defining characteristics of a mechanical firestop system. Rigid materials may be effective in certain areas but lack the adaptability that elastomeric materials provide. Additionally, while a mechanical firestop system may sometimes avoid bonding agents, that aspect is not a defining feature of its operation. Instead, the focus is on the flexibility and sealing capability that elastomeric materials bring to the firestop function.