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Can a dryer be vented through the roof?

Posted by bellaterra (My Page) on
Sun, Feb 18, 07 at 16:56

I am considering moving my dryer which would necessitate it being vented through the roof. Is there any reason why I would not want to do this or why it would not be possible?

Any advice would be greatly appreciated.


Follow-Up Postings:

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RE: Can a dryer be vented through the roof?

No, a dryer should not be vented through the roof. It should go out through a wall or the eve of a roof. It should have a cap on the end with a flapper, so that animals cannot get in.


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RE: Can a dryer be vented through the roof?

I have installed some dryer vents in attics and directed them out the eve. To get to the attic they had to go up approx 9 feet, then turn horizontal and go another 10 or 15 feet. They clogged up with lint, so I installed a booster fan made just for such applications (fantech dbf110a I think) but they need to be cleaned out every six months, and they are usually neglected.


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RE: Can a dryer be vented through the roof?

Nearly every single home in my subdivision (and it is a large one built around a golf course) has the dryer vented through the roof.

Now is it a good idea? That's highly debatable. Ours goes from the center of the house straight up to the attic and then it takes a 45 degree turn to go out the roof on the other side. It's about a 20 foot run.

We had to have professionals come out and clean it and had a different type of roof vent installed that wouldn't catch so much lint (as I've noticed several people have done) since the builder put on metal flap types with a mesh covering on them. With it so high on the steep roof, no one's going to get up there to clean it out very often.


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RE: Can a dryer be vented through the roof?

I haven't seen it in a manual in some time but many of the manufacturers used to say to never vent straight up higher than 15 feet.
I generally see problems with drying when the vent is going up through the middle of a 2 story house. These runs are around 25+ feet straight up and the dryer just can't push air that high. The blower has to fight the atmospheric weight of a column of air pushing down (14.7 psi at sea level). I have seen the inline fan tech blowers help in these situations.


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RE: Can a dryer be vented through the roof?

If you live in a cold climate, another potential problem is with condensation. If any of the hot humid air in the duct cools below the dew point you'll end up with water heading back into your dryer. Insulating the duct could help this, but why take a chance.


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RE: Can a dryer be vented through the roof?

Not ideal but it can be done. Mine is - single story 9 ft. ceiling. No problems.


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RE: Can a dryer be vented through the roof?

Thanks for all the replies. I live in the south, it's a one-story house with 8 ft. ceilings. The dryer would be stacked on a washer, so I could go up about 4 feet through the ceiling, then horizontal about 13 ft. to an eave. That sounds better/easier than going through the roof and having to deal with shingles, leaking, etc.

Am I thinking right?


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RE: Can a dryer be vented through the roof?

Yes, you are. Requirements: >Dryer vent must not exceed 25 feet. Each elbow counts as five feet. This is because of the sharp turn and the restriction it causes. Try to get long-radius elbows made just for dryer vents. These are relatively new on the market. >Do not use vinyl flexible vent at the dryer connection. Instead, install a recessed box in the wall and use a semi-rigid aluminum flexible vent connector. >No screws may be used to secure the pipe joints; only foil tape. There must be nothing in the airway which might collect lint. Get an all weather foil tape, 2 mil thick. Most contractors just use what the wholesaler stocks, not realizing (or caring) whether it will stay stuck over the years. >Ensure that male pipe ends are not re-crimped by the installer. Installers often make this end smaller than it needs to be instead of using a little patience to gently squeeze it to match the next section. >Do not protect the outlet with any kind of screen. Flap yes, screen no. >After installation, go outside and catch some lint. If it is hot and dry, you should be in good shape. If there is any moisture in the lint, you will have to have to clean the pipe every once in a while. Also feel the air stream. You should feel at least a gentle breeze from 3 feet away. >The box and the elbows are available from dryerbox.com.


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Clarification about lint moisture

If everything is installed correctly, lint in the pipe should be dry 15 feet away from the dryer. This is in linear pipe feet. Here the elbow does NOT count as 5 feet. If the pipe run is less than 15 feet, the lint will be moist at the outlet. If it is dry, and the run is less than 15 feet, this indicates that the lint has probably swirled in the stream before exit, and that you may have some obstruction in the line. Please bear in mind this is just a guideline, and by no means should it be accepted as gospel.


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RE: Can a dryer be vented through the roof?

Granted this is a dated thread, but the content is mixed along with some great guidelines for dryer venting posted by Airsome.

Venting dryers to a roof termination or roof cap is very common in the south. 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).

Roofers generally refer to these caps or terminations as roof jacks or specifically Dryer Jacks. By code they are required to exhibit a built in damper and NO screen or grill of any sort. Roof vents need to be selected carefully as there are vents for bathroom and range hoods that appear to be the same but include a screen and some do not include a damper.

Good efficiency pressure testing videos on YouTube. Search for DryerJack - New Low-Profile Roof Vent or Cap for the Dryer.

Here is a link that might be useful: YouTube video


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RE: Can a dryer be vented through the roof?

Yes you can. You can also put a 25' exhaust Pipe going straight Up on the back of your car or truck.

Both will work. But I doubt any contractor would do either of those to his OWN House or Truck.

Pushing any thing straight UP takes energy. Energy your dryer might not have to spare.

Your dryer will not be as efficient, break sooner and may cause a fire.

Allot of installers know they just have to make it work.
And they don't have to live there.


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RE: Can a dryer be vented through the roof?

90% of Condo dryers are vented through the roof.


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