Reuben Saltzman

Don’t Vent Your Clothes Dryer Through the Roof

As soon as I’m in charge, there will be no more venting of clothes dryers through the roof.  I think the roof is a stupid spot to terminate clothes dryer vents because it’s difficult to clean, and it’s a major contributor to ice dams.  Clothes dryers should be vented through the side of the house, preferably within reach from the ground.

Ice Dam Contributor

When bath fans and clothes dryers vent through the roof, they melt a bunch of snow.  After the snow melts below the vent, it’ll probably freeze again farther down on the roof.  If this happens enough, an ice dam will form that’s large enough to cause roof leaks. The photo below shows an ice dam formed in the middle of the roof below a couple of bath fans, but clothes dryer exhaust more air, and it’s even warmer.

The roof is especially susceptible to roof leaks in areas like this because there is no ice and water shield installed this high up on the roof.

Tough to Clean

As I mentioned in my blog post about keeping your clothes dryer safe, the terminals for clothes dryers need to be cleaned on a regular basis.  These terminals got covered with lint, causing the dampers to be stuck open.

dryer terminal in need of cleaning

Eventually, the terminal will get so filled with lint that airflow is obstructed, which will reduce the performance of the clothes dryer and could actually cause a fire. Cleaning the dryer terminal at old houses is usually a piece of cake; the lint can just be wiped off and pulled out by hand. The dryer terminal is easy to access at these houses because laundry rooms used to be installed in basements or on the first floor… but not anymore. For nearly the last twenty years, the standard for new two-story homes has been to install a laundry room on the second floor. When that happens, where does the dryer duct go? Through the roof, of course. Most of the time.

Dryer duct through roof

This arrangement will work fine at first, but just like dryer vents that go through the side of the house, the terminal will eventually get clogged with lint. The photos below are from a  home with a badly clogged dryer vent terminal at the roof.

Dryer Terminal at roof

Clogged dryer terminal at roof
While I usually don’t perform repairs or home maintenance chores at homes while I’m inspecting them, I couldn’t help but pull some of the lint out.  There was enough to start several campfires.
Ball of lint pulled out
If you’re having a home built, try to have your builder terminate the dryer duct at a location that makes sense. It’ll be an uphill battle because most builders aren’t flexible with stuff like this. But still. In my humble opinion, dryer vent terminals should be accessible from the ground.
If you already have a home with a dryer that terminates at the roof, be sure to have the terminal cleaned on a regular basis, and consider having the terminal replaced with a  DryerJack terminal. It’s designed to outperform all of the other cheap ones. I don’t have any personal experience with these, but I’m a fan of the company that makes them: In-O-Vate Dryer Products. They make a bunch of products designed to make clothes dryers perform better. I tested their DryerFlex product many years ago and blogged about it here:  DryerFlex: A Superior Dryer Transition Duct.

5 responses to “Don’t Vent Your Clothes Dryer Through the Roof”

  1. Brian A Dawson
    June 25, 2014, 8:28 am

    Great blog post. I am always amazed at the number of home inspectors that don’t give the dryer venting a second look let alone “inspect it”. Kudos to putting this topic out there for people to read. More homes are suffering from blocked and restricted dryer vents but few people know they need to provide periodic maintenance to keep the air moving properly. This not only saves money, but can save significant damage to your dryer and home.

  2. level 380
    August 3, 2014, 6:51 pm

    Great advice re roof vent…. The other option is to use a dryer that doesn’t need venting at all. A condenser dryer doesn’t need outside air vent as they capture water in a container or a pipe out to a drain.

    So if you have a roof vent and your dryer dies, think about changing the type of dryer!

  3. Bob
    August 12, 2014, 5:54 am

    Also DO NOT terminate near AC condensing units !!

  4. Andrew
    January 30, 2024, 4:40 pm

    I’m in Phoenix. LOL

  5. George Benigno
    January 31, 2024, 12:41 pm

    Great article. Florida is notorious for this issue. Builders say homeowners want the laundry inside the house AC envelope which is usually not against an exterior wall. You need to create a homeowner manual on issues like this. As home inspectors you have seen it all by builders, contractors and DIY homeowners. Thanks

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