What are the code requirements for an outdoor dryer vent cover?
Monday, August 6, 2018
It’s called a “duct termination” in the “Clothes Dryer Exhaust” section of the International Residential Code (IRC) and the Residential Edition of the Florida Building Code (FBC). Here’s what is specified:
- Termination of the exhaust duct must be outside the building.
- Termination should be in accordance with the dryer manufacturer’s instructions.
- If no duct termination location is specified by the manufacturer, then it must terminate a minimum of three feet from any opening in the building.
- The termination must have a backdraft damper
- The termination cannot have a screen.
So requirement #1 means that any indoor bucket-type device to catch dryer lint and condensation is not acceptable. Flaps that self-close by gravity or a configution with a U-shape end meet standard #4.
But #5 eliminates approval of the protective coarse screen cover, sold as a “bird guard,” like in the photo above. It's an obstruction that catches lint, and one manufacturer of this type of dryer vent termination acknowledges the problem with a warning that you should “check periodically and remove lint or other debris, if present.” The intention of the code is to avoid any design that would trap lint and allow it to build up to start a fire. Fire departments in the U.S. respond to an estimated 14,000 fires each year started by clothes dryers.
Also, see our blog posts How do you inspect a dryer vent? and What is the maximum length for a clothes dryer vent?
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