Broan-NuTone LLC 634M roof cap accessory

Roof cap for six-inch round duct

The Broan-NuTone 634M roof cap fits a six-inch round duct and installs on the roof to terminate a bathroom ventilation run. A built-in cushioned backdraft damper and bird screen keep outside air and pests from entering the duct when the fan is off. The black epoxy finish resists weathering and matches common roof colours. Homeowners and contractors use it to complete a code-compliant exhaust system.

Steel construction with integrated damper under

The steel housing and epoxy coating withstand repeated thermal cycles from hot, moist exhaust without warping. The cushioned damper seat reduces flap chatter when wind gusts hit the cap, so the seal remains tight over years of daily use. The integral bird screen does not clog with lint because the damper blocks debris when the fan stops. This combination keeps airflow steady and prevents backdrafts during sustained fan operation.

Six-inch nominal duct diameter is the deciding fit

The cap accepts only a six-inch round duct; any other diameter requires a transition piece not supplied with this unit. Verify the duct size before purchase because the opening cannot be enlarged or reduced in the field. If the project uses a different duct size, this model will not connect directly.