Bath Exhaust Fan Duct Length

A bath vent fan duct that is too short may violate the manufacturer s installation instructions may not work properly or may be drafty.

Bath exhaust fan duct length.

Just remember that the fan needs airflow to do its job. A 3 or 4 inch duct connects to the outlet on the fan housing and runs to a side wall or to the roof and connects to a vent cap that allows the. Bathroom exhaust fan duct length specifications. The bath fan calculator is standard guide to help you find the minimum fan rating for your specific bathroom.

If your bathroom has a toilet or shower area enclosed by a door it s a good idea to install a separate exhaust fan for that area. Otherwise use the appropriate calculation based on the room size. If the enclosed space is small a 50 cfm fan should suffice. Result maximum recommended length of straight duct in compliance with 2015 irc section m1506 2 and 2018 irc section m1504 2 ft 0 ft nl no limit on duct length for the specified system.

A second fan may be needed. Press calculate minimum suggested bath fan cfm. Enter bathroom width ft. The bathroom exhaust ventilation fan disperses air through an opening in the fan housing which is usually 3 inches in diameter and ideally faces in the direction of the ventilation system outlet.

Enter bathroom length ft. Enter bathroom height step 4. A bath vent fan duct that is too long may restrict air flow such that the fan is not functional.