What type of material should be used to seal the annular space where a clothes dryer exhaust duct penetrates a wall or ceiling?

The use of noncombustible material to seal the annular space where a clothes dryer exhaust duct penetrates a wall or ceiling is essential for safety and code compliance. Noncombustible materials do not ignite or contribute to the spread of fire, making them the ideal choice in this scenario, where there is potential for heat and lint accumulation in close proximity to combustible surfaces.

Sealing this space properly prevents air leakage, which can improve dryer efficiency and reduce the risk of lint buildup around the duct. It also helps to maintain the integrity of the wall or ceiling structure, contributing to overall fire safety within the building. Noncombustible materials provide a barrier that minimizes potential hazards associated with dryer operation, especially in a utility area where flammable materials may be present.

While other options may seem plausible, such as metallic sheeting or approved sealants, they do not universally offer the same degree of fire safety and reliability as noncombustible materials in this specific application. Metallic sheeting, for example, could be a suitable component of a duct system but may not provide the necessary sealing properties needed in this instance. Approved sealants must also be specifically rated for this type of application to be considered appropriate, whereas noncombustible material inherently meets the