All clothes dryers have different types of filters to catch the lint generated as clothing tumbles inside the dryer, but the filters cannot catch all the lint. Some amount of lint inevitably passes into the ductwork leading to the outdoor vent, and proper maintenance requires that you clean this ductwork regularly.

Why Dryer Ducts Need to Be Cleaned

The U.S. Fire Administration reports that every year more than 2,900 home fires are started by clothes dryers, and the leading cause of these fires is a buildup of lint due to lack of simple maintenance on the part of the owner. Each load of laundry that passes through your washing machine and makes its way to your clothes dryer contains lint—mostly small particles of cloth and fiber that are loosened from clothing by the action of agitating water.

The removable lint filter in your dryer simply cannot catch all the lint freed from clothing. The lint that makes it past the filter gets trapped in crevices deep inside the lint filter trap and all along the dryer ductwork as it makes its way to the outside vent opening. When the lint builds up, they restrict airflow and lead to overheating, which can ignite the lint itself.

There are several warning signs that dangerous lint buildup has occurred in your dryer ductwork system, indicating that it needs a thorough cleaning:

• Clothes take longer to dry or don’t dry fully
• Clothes are hotter than normal at the end of the drying cycle
• Outside of dryer gets very hot
• Outside exhaust vent flapper does not open very much, indicating low exhaust velocity
• Laundry room becomes more humid than usual
• Burnt smell is evident in the laundry room

Safety Considerations Before Starting

The flexible plastic or metal foil ductwork that was once commonly used to connect dryers to outside vents are now forbidden by most local building codes. These vent tubes were popular because of the ease with which they can be routed through difficult spaces, but because their inside surfaces are ribbed, they can easily catch lint and cause fires due to overheating.

If you have one of these flexible ducts installed, it is best to replace it with smooth-walled metal ductwork approved for this use. If you can’t remove and replace the old ductwork, then it should be regularly removed and carefully cleaned out from one end to the other.

Special Brushes Are Needed

Thorough dryer vent cleaning requires special brushes. Vacuum attachments alone do not work as well because they do not agitate the lint to remove it from the walls of the duct, and they can’t reach deep enough inside the dryer’s lint filter housing.

Brush kits come with a long-bristle brush to clean the lint filter area, as well as a round-bristled brush that can clean out a 4-inch round rigid dryer duct—the kind you should have for all concealed portions of your duct run. The round brush tip fastens to a flexible fiberglass shaft that can be lengthened in sections.