Water dripping from a dryer vent is usually condensation: warm, wet exhaust cools inside a long or sagging duct and turns back into water. Less often, rain gets in through a damaged roof or wall cap. Either way, the fix is almost always in the ductwork, not the dryer.
Quick diagnosis
| Symptom | Likely cause | First thing to try |
|---|---|---|
| Drips at the outside cap while drying | Condensation in a long duct run | Check that the cap flap opens freely and air pushes out strongly |
| Water in the drum after a rainstorm | Rain getting past a roof or wall cap | Look at the cap from the ground for a stuck flap or damage |
| Puddle behind the dryer | Water collecting in a low spot or a loose joint | Pull the dryer out and check the transition duct |
| Drips or stains at a soffit or eave, with no vent cap | Duct ending at a soffit instead of a proper cap | Have the run rerouted to a wall or roof cap |
| Stains on a ceiling or wall near the run | Duct disconnected inside the attic or wall | Stop using the dryer until the run is inspected |
A closer look
Condensation in long runs
Dryer exhaust carries a lot of water. When the duct passes through cooler air, such as a winter attic, some of that moisture condenses on the duct walls. Long runs and many bends slow the air and give it more time to cool, so shortening the run helps.
Rain at the cap
Roof and wall caps have a flap or damper that should open when the dryer runs and close when it stops. Lint, a bird's nest or storm damage can hold it open and let rain in. Inspect from the ground and leave roof work to a roofer or vent service.
Low spots and loose joints
A duct that sags between supports forms low spots where water sits, mixes with lint and turns into a damp plug. Joints should be sealed with foil tape rather than screws, because screw tips poking into the duct catch lint. A joint that pulls apart in the attic dumps humid air and lint there instead.
A vent that ends in the wrong place
Dryer exhaust has to end outside the building through a proper cap. Some runs stop at a soffit or just short of the roof deck instead. Moist air then drifts back into the attic through the soffit vents and condenses on wood and insulation.
Why Houston homes see this more
Many Houston-area homes vent the dryer up through the attic to a roof cap, which means long runs, several turns and a cap that takes the full force of heavy downpours. On cooler winter days the attic can sit well below the exhaust temperature, and that's when roof-vented runs tend to drip.
Prevention checklist
- •Clean the lint screen every load
- •Use rigid metal duct for the run and a metal transition duct behind the dryer, never plastic or vinyl
- •Support long horizontal runs so they don't sag
- •Insulate duct sections that pass through unconditioned space
- •Check the outside cap flap a few times a year
Time to call a pro
- •Water stains on ceilings or walls near the vent path
- •A duct disconnected in the attic or inside a wall
- •Water keeps showing up after the cap and joints check out
- •Water reaching the dryer's controls, cord or outlet
Travis's rule of thumb: A dryer vent should only ever push out warm air and a little lint. Water means the duct needs attention.
If water has reached the dryer itself, see our dryer repair page or call ProFix Houston at (832) 552-1615. Seeing fuzz on the laundry too? Here's why lint ends up on clean clothes.