Dryer Vent Fire Risk: A 10-Minute Check Before Heating Season

Clothes dryers start about 2,900 home fires a year in the U.S., according to the U.S. Fire Administration. The leading cause is simple: nobody cleaned it. Lint is mostly fine fibers, and a duct packed with it sitting next to a heating element is kindling.

Fall is a good time to check, because laundry loads get heavier with sweatshirts, blankets and towels, and a clogged vent outside often gets worse once leaves and snow show up.

01Signs the vent is clogged

• Clothes take two cycles to dry, or come out hot and still damp.
• The dryer or laundry room gets unusually hot.
• A burning smell when it runs.
• The outside flap barely opens when the dryer is running, or doesn't open at all.
• Lint around the outside vent, or on the floor behind the dryer.

02The 10-minute check

1. Clean the lint screen and look at it. If it's coated with a film from dryer sheets, wash it with a brush and dish soap. Hold it under the faucet: water should run straight through.
2. Pull the dryer out and unplug it (for gas dryers, be careful not to kink or strain the gas line).
3. Look at the duct. It should be metal. White vinyl or foil accordion duct is a fire hazard and should be replaced.
4. Disconnect the duct and clean it out with a dryer-vent brush kit. You'll be surprised what comes out.
5. Check the hole in the back of the dryer where the duct connects. Vacuum out what you can reach.
6. Go outside with the dryer running. You should feel strong airflow and the flap should open. Clear out any lint, bird nests or leaves.
7. Reconnect with foil tape or clamps, not screws. Screws stick into the duct and catch lint.

03What the duct should look like

• Rigid or semi-rigid metal duct, as short and straight as possible.
• Building codes generally limit the run to 35 feet, and every bend takes away from that (about 5 feet for each 90-degree turn). A long run with several elbows clogs much faster.
• No crushed sections behind the dryer. Pushing the dryer tight against the wall is how most ducts get flattened.
• A proper exterior hood with a flap, never a screen. Screens catch lint and clog.
• Venting outside, never into the attic, crawlspace or garage.

04How often

Clean the lint screen every load. Clean the duct at least once a year, more often for big families or long duct runs. If the run is long, goes up through the roof, or you can't reach it, hire a dryer vent cleaning service.

05Other dryer fire habits

• Don't run the dryer when you leave the house or go to bed.
• Don't dry anything that has gasoline, oil, cooking grease or cleaning solvents on it.
• Keep the area around the dryer clear of boxes, laundry piles and cleaning products.

Every home should have working smoke and CO alarms, especially on the laundry floor. Dryer vents are also on our fall home inspection checklist.

Sources (2)

U.S. Fire Administration: Clothes Dryer Fires in Residential Buildings · UL: Mitigating Clothes Dryer Fires

Related: A Comprehensive Guide to DIY Home Inspection: Safeguarding Your Home Inside and Out