Short answer: Stop the dryer if you smell burning. If you smell gas, leave the house and call your gas or propane company from outside. A musty or dead-animal smell almost always comes from wet lint, a nest, or an animal that got into the line through a broken or stuck-open flap. Get the line cleaned out, then fix or replace the outside hood so the flap closes. Skip the screen: the International Residential Code doesn’t allow screens on dryer vent terminations because lint clogs them.
What does the smell from my dryer vent mean?
The kind of smell tells you how urgent it is. Burning and gas are emergencies; musty, dead-animal and sewer smells are not, but they mean something is in the line or nearby drains.
| Smell | Likely cause | What to do |
|---|---|---|
| Burning or smoke | Lint overheating in the dryer or the vent, or a worn belt or motor in the dryer | Turn the dryer off and unplug it if it’s safe to reach. If you see smoke or flames, get out and call 911. |
| Gas | A leak at a gas or propane dryer or its supply line | Leave the house. Don’t use light switches or your phone inside. Call your gas or propane company, or 911, once you’re outside. |
| Musty or mildew | Lint that stays damp in a long run, a cold attic or a roof vent | Get the whole line cleaned and check that the hood flap opens and closes. |
| Dead animal | A bird or rodent that died in the line or the hood | Get it out and clean the line. See the cleanup steps below. |
| Urine or sewage | Droppings or nesting material in the vent, or a dried-out floor drain or washer drain trap in the laundry room | Pour water into nearby floor drains, then check the vent for an animal. If it persists, call a plumber. |
What do I do if there’s a bird in my dryer vent?
- Stop using the dryer. Running it won’t push the bird out. It traps heat and lint behind the nest and can kill the bird or its chicks.
- Look at the outside hood for twigs, grass or a bird going in and out. Chirping inside the wall in spring or summer usually means chicks.
- Figure out what kind of bird it is before you touch the nest (see below).
- Once the nest is empty or legal to remove, get the whole line cleaned, not just the hood. Nesting material often gets pushed back into the duct.
- Fix or replace the hood so the flap closes when the dryer is off.
Can I remove a bird nest from my dryer vent?
For house sparrows and European starlings, yes. They’re two of the most common dryer vent nesters, they aren’t native, and they aren’t protected by the federal Migratory Bird Treaty Act. Vermont’s nest law (10 V.S.A. § 4905) also leaves them out.
Nearly every other bird is protected, including house wrens and house finches, which also nest in vents. You can’t remove an active nest with eggs or chicks without a federal permit, and you can’t scare the birds off it either. Wait until the young have left. Vermont law allows removing a nest to protect a building once it has no eggs or chicks and the birds aren’t using it anymore.
Is a bird nest in a dryer vent dangerous?
Yes. A nest is dry grass, twigs and feathers sitting in the path of hot, lint-filled air, and it blocks the airflow the dryer needs. On a gas or propane dryer, a blocked vent can also push carbon monoxide back into the house, so make sure you have a working CO alarm. Clothes taking longer to dry, weak air at the outside hood and a hot laundry room are the usual warning signs (see signs of a clogged dryer vent).
How do I clean up after a dead animal or droppings in the vent?
Unplug the dryer, and shut off the gas on a gas dryer. Wear gloves and an N95 mask. Don’t sweep or vacuum dry droppings or nesting material, since that puts dust in the air. Spray them with disinfectant or a bleach solution, let it soak, then wipe up and bag it.
How do birds and mice get into a dryer vent?
- A broken or missing flap on the outside hood.
- A flap held open by lint, so it can’t close when the dryer is off.
- A hood that’s cracked or pulled away from the siding.
- A vent close to the ground, where mice and chipmunks can reach it.
How do I keep birds out of my dryer vent?
Use a hood with a backdraft damper that closes when the dryer is off, and keep it clean so the flap doesn’t stick. Don’t put a screen or mesh cage over it. The International Residential Code (M1502.3), the model code most US building codes are based on, requires a backdraft damper at the termination and says screens shall not be installed, because lint builds up on them and blocks the vent. If the hood or the duct behind it is damaged, see dryer vent replacement.
Frequently asked questions
Why does my dryer vent smell like something died?
An animal got in through a broken or open flap and died in the line or the hood. It has to come out, and the line should be cleaned before you use the dryer again.
Why does my dryer vent smell musty or like mildew?
Dryer exhaust carries a lot of moisture. In a long run, a cold attic or a roof vent, some of it condenses, the lint stays wet and it starts to smell. Cleaning the line and fixing the airflow takes care of it.
Why does my dryer smell like burning?
Lint may be overheating in the dryer or the vent. Turn it off and don’t use it until the vent and lint trap area are cleaned. If the vent is clear and the smell comes back, have the dryer itself serviced; a belt or motor can smell like burning, too.
Why does my dryer vent smell like sewage?
Check the laundry room floor drain or washer drain first. When the water in the trap dries out, sewer gas comes up, and the dryer can pull it through the room. Pour water in the drain. If that doesn’t fix it, look for droppings in the vent.
Why does my dryer vent smell when the dryer is off?
The outside flap is probably stuck open, letting outdoor air and anything living in the vent back into the house. Clean the line and fix the flap.
Can a mouse get into my house through the dryer vent?
It can if the flap doesn’t close or the hose behind the dryer is loose or torn. Fix the hood and make sure the connection at the dryer is tight.
Can I put a screen over my dryer vent to keep birds out?
No. Lint collects on screens and blocks the airflow, which is why the model code bans them. Use a hood with a damper that closes.
Related guides
- How often should you clean your dryer vent?
- Signs your dryer vent is clogged
- Why is the “Check Vent” light on?
- Cleaning your dryer vent yourself vs. hiring a pro
- How much dryer vent cleaning costs
- Dryer vent replacement
- Roof-vented dryers in Vermont
Sources
- Cornell Lab NestWatch: Managing House Sparrows and European Starlings
- Audubon: I found a bird nest in a bad location. What can I do?
- Vermont Statutes: 10 V.S.A. § 4905, Birds’ nests and eggs
- IRC M1502.3 Duct termination (model code text)
- Connecticut PURA: What to do if you smell natural gas
Animal gone, vent still a mess?
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