You can clean most dryer vents yourself with a brush kit and about an hour. The question is whether your vent is short enough and straight enough to make that practical. Here’s how to tell, and what to do when it isn’t.
Why vents clog in the first place
Every load of laundry sends warm, humid air through your vent to the outside. Lint travels with it. Most lint stops at the screen inside the dryer (the filter you clean after every load), but a percentage slips through into the duct itself.
Over a few years that accumulates. Add any moisture and you get a sticky, compressed layer that restricts airflow. Vents near exterior walls with bird access are especially prone to nesting blockages in spring.
The other common culprit is the duct material itself. Older homes often have flexible plastic or foil accordion duct that’s been compressed behind the dryer. Every bend and every inch of compressed material adds resistance. That’s the kind of thing you can’t fix with a brush.
What tells you the vent needs attention
The dryer is taking two or three cycles to dry a normal load. That’s the clearest sign. A few others:
- Clothes come out hot but still damp
- The laundry room feels warm and humid while the dryer is running
- The exterior exhaust flap barely moves when the dryer is on (hold your hand near the outside termination)
- The dryer is shutting off mid-cycle (most modern dryers have a thermal fuse that blows when the unit overheats, and replacing it without fixing the airflow restriction just means it blows again)
A completely blocked vent can cause a dryer fire. NFPA data consistently identifies failure to clean the dryer and vent system as the leading contributing factors in home dryer fires. It’s not a scare tactic, it’s just a real failure mode with real consequences.
What you can do yourself
For a short, accessible duct run, DIY cleaning works fine. You need a lint brush kit with flexible rods (these sell for $25-50 at hardware stores and online), a vacuum with a narrow attachment, and some patience.
The process:
Pull the dryer away from the wall. Disconnect the flexible transition section of duct from the dryer’s exhaust port and from the wall connection. Take that flexible section outside and shake it clean. Vacuum both openings.
Then feed the brush kit into the wall duct toward the outside termination. Most kits let you extend rods as you go. Work slowly and pull lint back toward you.
Go outside and clean from that end too. Remove the flap cover (usually one or two screws), vacuum out any debris, and run the brush in from the exterior a foot or two.
Reconnect everything, turn the dryer on a short cycle, and stand outside to confirm you’re getting good airflow from the exterior vent.
This works reliably if your duct run is within the range a basic kit can reach — typically under 15 to 20 feet of actual duct — with no more than a couple of 90-degree bends. That covers a lot of laundry rooms.
Where DIY stops making sense
Long or complex duct runs. Current code (IRC 2024) allows up to 35 feet of equivalent duct length, with 5 feet deducted per 90-degree elbow. Many homes, especially two-story houses with the dryer on an upper floor, have duct runs that a basic brush kit can’t reach or clean effectively. You’d need a rotary brush system on a longer reach, which is what technicians use.
Rigid metal duct buried in a wall or ceiling. Some homes have the duct run inside a wall cavity or above a drop ceiling. You can clean the ends, but you can’t address what’s in the middle without professional equipment.
Bird or rodent nests. This happens more than people expect, especially with rear-exit vents close to the ground or side-exit vents under roof overhangs. A nest isn’t just a blockage; it’s compressed material that a brush can push further in and make harder to extract. It also means your exterior termination cap isn’t sealing properly, which needs to be addressed at the same time.
Foil accordion duct throughout. If the full duct run from the dryer to the exterior is flexible foil (the silver accordion style), it should be replaced with rigid metal rather than cleaned. Flexible foil collects lint in the corrugations, crimps easily, and isn’t permitted for full duct runs under current code. A short section at the dryer connection point is allowed, but not the whole run. Replacement isn’t a cleaning job.
If you’re not sure where your duct exits. Some older homes have dryer vents that were routed into a crawlspace or attic in ways that don’t meet current requirements. If you can’t locate your exterior termination, don’t guess.
When to call a pro
Call someone if your duct run is long, if you find or suspect a nest, if the duct is flexible foil that should be replaced, or if you’ve cleaned the accessible portions and the dryer is still underperforming.
A professional cleaning uses a rotary brush on a drill-powered extension system that clears the full length of the duct and pulls debris out rather than just dislodging it. It takes 30 to 60 minutes for most homes. If your duct needs replacement, that’s a separate scope but usually straightforward for a technician who does it regularly.
If you’re in the Tri-Valley or East Bay and your dryer is underperforming, we can diagnose whether it’s the machine or the vent and tell you straight. Vent cleaning itself isn’t a service we offer, so we’ll point you to a specialist if the duct needs it. No pressure either way. More at adriumservice.com.