How a Roof Dryer Vent Gets Cleaned

Why a Roof Termination Is Harder to Clean

A wall vent is a short, level run you can reach from a ladder. A roof vent climbs: out of the laundry, up into the attic, often across it, then up through the roof deck to a low cap with a flap. Lint has to be blown up that whole climb, and it settles at each elbow and against the flap at the top.

That shape decides the method. Brushing from below alone tends to push lint up into the cap, where it packs against the flap. Clearing the cap alone leaves the lint in the turns. A roof dryer vent is cleaned from both ends, and the job is not done until the cap's flap is seen to open with the dryer running.

Power, Gas and the Lint Screen Before You Start

Unplug an electric dryer before you move it; GE's care steps start by disconnecting the plug. On a gas dryer, leave the gas connection alone: Whirlpool's instructions say installation and service are for a qualified installer, service agency or the gas supplier.

Clean the lint screen first, as the CPSC advises for every load, and note how long a normal load takes to dry. That number is your before-and-after test.

Step One Is Cleaning From Below

Pull the dryer out far enough to reach the transition hose, then take the hose off the dryer outlet and the wall collar. The CPSC notes that clearing a blockage may mean disconnecting the duct from the dryer, and reminds you to reconnect it before the dryer runs again.

Shake out and brush the transition hose. A foil or plastic hose should be replaced rather than cleaned. Then work a dryer vent brush on flexible rods up into the wall collar, turning it in the direction the rod kit's instructions give so the sections do not unscrew inside the duct. Feed it in short lengths, pull it back often, and let a vacuum at the collar catch what falls.

• Unplug the dryer; leave any gas line alone.
• Disconnect the hose at the dryer and at the wall.
• Brush and vacuum the hose, or replace it if it is foil or plastic.
• Feed the brush up the duct a few feet at a time, pulling back often.
• Vacuum the collar and the floor behind the dryer before reconnecting.

Step Two Is Clearing the Roof Cap

Lint that the brush pushes upward ends up under the cap's flap, which is why the roof end has to be cleared too. On the roof, the cap's flap is lifted or the cap's face removed, packed lint is pulled out by hand, and the last few feet of duct are brushed downward. The flap and its hinge are cleaned so the flap drops shut on its own.

This is the step to think hard about. A roof is a fall hazard, more so when it is wet, steep or hot, and a cap may need tools and flashing care to open. If you are not equipped and practised on roofs, stop at step one and leave the cap to a crew with fall protection.

Step Three Is the Cap Check That Finishes the Job

With everything reconnected, run the dryer. The CPSC advises checking the outside vent while the dryer operates to make sure exhaust air is escaping, and Whirlpool suggests running it 5 to 10 minutes before feeling for air movement under the hood. On a roof cap you can do this from the yard: watch for the flap to lift and stay up, with a shimmer of warm air above it.

When the dryer stops, the flap should drop shut. GE asks owners to check that the hood flaps move freely and that nothing is nesting inside. Then dry a normal load and compare the time with the number you noted before.

What the Roof End Has to Be When You Are Done

The 2023 Florida Building Code, Residential, section M1502.3 requires the termination to have a backdraft damper and no screen, and section M1502.3.1 keeps at least 12.5 square inches of open area. If you found a mesh screen under the cap packed with lint, it should not be there. If the flap is broken or missing, the cap needs replacing rather than cleaning. Joints you reconnect are clamped, not screwed, because screw tips inside the duct catch lint.

If the dryer is still slow after both ends are clean, the problem is probably in between: a crushed section, a joint that has come apart in the attic, or a run longer than the dryer's maker allows.

When to Leave It to Us

Stop and call when the brush jams and will not come back, when you find lint in the attic insulation, when the roof is wet or steep, or when the flap stays shut with the dryer running. Those are signs of a blockage or a broken joint that a brush from below cannot fix safely.

Roof runs are cleaned by experienced technicians from our locally owned, family-run company, which is Proudly American. Our dryer vent cleaning covers both ends of a roof run, with the cap check at the end. Book a free inspection and you get a written estimate before any work starts; as a Proudly American family business, we keep the price in writing and the roof work to us.