Running Dryer Vent Out Roof

Dryer on basement floor with duct running up block wall and out rim joist.

Running dryer vent out roof.

When bath fans and clothes dryers vent through the roof they melt a bunch of snow. Venting dryers to a roof termination or roof cap is very common in the south. The sheet metal duct is cooled by the outside air in the attic. Air velocity reduction from friction loss promotes lint build up and makes the dryer work harder to completely dry each load.

Whether you re installing a new vent or upgrading an existing one the first step in installing dryer vents is to determine where the dryer duct will run. The issue i have is i was going to run from the attic floor to the roof and out with a roof vent in 4 smooth aluminum duct. Every turn increases friction loss unless you use non restrictive elbows. Before climbing up to the roof get behind the dryer to vacuum out the vent.

The international residential code allows you to run a dryer vent through the attic but you can t terminate it there. But that condensation is quickly evaporated by the fast moving hot air produced by the dryer. You can put the tube of the vacuum directly up the vent. These terminals need to be cleaned on a regular basis to prevent lint buildup.

If you install an uninsulated galvanized dryer vent in an attic the duct will indeed be cold during the winter when the dryer is not operating. Since many laundry rooms are located in the middle of the house and so many homes are single story with easy to walk on roof slopes about 6 12 venting the dryer to the roof makes the most sense shortest run with least amount of elbows. Doing so would fill your attic with warm moist air that could rot the framing. This causes the steam from your dryer.

If this happens enough an ice dam will form that s large enough to cause roof leaks. Difficulty cleaning dryer vent dryer vents should always be vented through the side of the house and not vented through the roof and ideally the exit should be fairly close to the ground. There should be clamps that connect the exhaust pipe of the dryer to the vent. The pluming in the wall is similar to a periscope going 8 feet up into the attic inside the wall it is rectangular and has a 4 connection at the laundry room the kicker is it has a 3 round connection in the attic.

A vertical dryer vent is typically a problem because it acts as a moisture condenser. Once the dryer starts up condensation could form on the inside of the duct. Dryer vent installation can be a bit of a challenge. After the snow melts below the vent it ll probably freeze again farther down on the roof.