How it works

The hood mounts over the exterior end of the rigid metal vent duct, sealed against the wall with caulk and fasteners. The internal damper sits at rest closed under spring pressure or gravity, opening only when the dryer’s exhaust airflow pushes against it. When the dryer cycle ends, the damper falls or springs back closed, preventing outside air, insects, and pests from entering the vent and migrating into the laundry room.

A failed hood damper causes either reduced dryer airflow when stuck partially closed or pest intrusion when stuck open. Sweeps inspect hood condition during dryer-vent cleaning visits, replacing damaged hoods or rebuilding worn dampers. The hood must include no screen or guard mesh because lint accumulation on such surfaces is a documented fire-ignition risk in dryer-vent applications.

DFW context

DFW dryer-vent hoods take significant abuse from sun, hail, and the occasional curious wildlife encounter. The June 2025 hailstorms damaged thousands of plastic vent hoods across the metroplex; metal replacement hoods provide more durable service. TSE replaces failed hoods during dryer-vent cleaning service, and most installations use a 4-inch metal hood with hinged-flap damper that delivers 15-plus years of service in DFW conditions.

Related terms

• [Lint](/glossary/lint/)
• [Rigid metal duct](/glossary/rigid-metal-duct/)
• [Bird flap](/glossary/bird-flap/)
• [Roof vent termination](/glossary/roof-vent-termination/)

Sources

• IRC 2021, Section M1502.3
• UL 2158A Standard for Dryer Transition Ducts
• ASHRAE 62.2 ventilation standard