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The Dryer Vents Through The Roof - Is It Leaking Air Inside The Attic?

The dryer vents through the roof - is it leaking air inside the attic?

One of my pet peeves is seeing that the dryer vents through the roof.

To me common sense says it's a bad idea.

Why?  Look at the diagram to the right.  This is probably the most typical dryer vent hood that I see when it is installed on a roof.

This about why I don't like seeing this. 

1.  How do you know when the dryer vent is clogged?

YOU SEE IT.  When the vent is on the roof, how can you see it?  At this subject house, a townhouse, I could not see the rear roof from the yard.  It was three stories high.  To see the dryer vent I had to go to the end of the townhouse row behind and look at it from a distance with my 20X binoculars!  And even then I could not tell.

2.  What do you do when the dryer vent opening is clogged?

YOU CLEAN IT.  How do you do that when the vent opening is high on the roof?  Someone needs to go on to the roof!  At this house you would need a very tall ladder, or hire a company with one.  This height would require two people to manage the ladder.  Then you would have to trust that they did a good job.

3.  How often does the dryer vent need cleaning?

WHEN IT CLOGS!  How many people live in the house?  How often do you do wash?  Do you wear a lot of cotton that creates more lint?  Is the weather cold where you live (which creates more condensation at the vent opening, making it stickier)?  So the answer to #3 is - who knows!

So, from inside this attic the view you see in this photo is about the view I had when up there.

The sheathing is about 18' above the attic access opening.

I see what looks like stains on the sheathing and roof framing.

I see what looks like lint, or maybe white fungus.

I see what appears to be lint blowing in the breeze.  It's really hard to tell if it is clogged and leaking back into the attic.  So how can I find out?

To test this I turned on the dryer and waited about 10 minutes.  Then I broke out Mighty Mo!

I selected this palette because it is very descriptive.

On the left side of the vent tubing you can actually see where the warm air is blowing onto the shingles above as the sheathing is warm.

So the vent is blowing air outdoors.

But on the right side it looks like air may be leaking into the attic.  But if there is a clog it might not be much of one because air is surely blowing out.

Does the image indicate a loose connection of the tubing to the hood?  Perhaps.  The warm air seems to be blowing a distance toward the right.  This point is about 30' from the dryer, so 98F is pretty warm I guess.

But is it clogged?  That is hard to know!

My recommendation:  while very descriptive, a thermal image in this case was not definitive.  It is interesting, and does show a pattern.  The house is 10 years old, so this may be a leak in the connection at the roof sheathing.  In speaking with the seller it was learned that there was a severe clog, and all of the vent tubing was replaced from the dryer to the roof.  That would account for the stains.  As to the leaking air?  Perhaps a loose connection.  Is it a problem?  Likely not unless it pops off.

 

 

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


Comment balloon 16 commentsJay Markanich • February 27 2016 02:49AM

Comments

A good example Jay Markanich  of location location location..hmmm ?  Getting accurate information from a roof location is a difficult destination.

Posted by Sally K. & David L. Hanson, WI Realtors - Luxury - Divorce (Keller Williams 414-525-0563) over 2 years ago

And all this contributes to why I don't like roof dryer vents, S&D!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Good morning Jay. Dryer vents through the roof are not my favorites either. Owned a home where the dryer was not efficient. Had the vent cleaned yearly and the problem disappeared. Enjoy your day!

Posted by Wayne Martin, Real Estate Broker (Wayne M Martin) over 2 years ago

That's often the solution, Wayne.  Nail hit on head.

Another roof problem is when it snows deeply the dryer vent is covered up!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Don't like roof dryer vents! When it rains, water almost always splashes back up onto the flapper, then it collects lint. Not to mention the length of the duct vertically! Gimme a straight shot through the exterior wall anyday! 

 

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) over 2 years ago

My inspection this morning had the vent straight out through the wall beside the third-story laundry room, Fred.  It's high, but not as high as a roof and easier to see.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

I too am not a big fan of roof dryer vents. Our vent is at the side of the house and easy to see and get to - important in our opinion. Thanks for sharing your expertise with us, Jay. D

Posted by Debb Janes EcoBroker and Bernie Stea JD, REALTORS® in Clark County, WA (ViewHomes of Clark County - Nature As Neighbors) over 2 years ago

Agreed Debb.  This has been a pet peeve of mine for ages!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

 Good morning Jay Markanich . It is very interesting with thermography will reveal. Thank you.

Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) over 2 years ago

'Tis Michael.  It was far away and I tried my best to get a good look!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

The heated air will always rise, but the wet fibers and water want to drop down sideways would have been more efficient

Posted by Ed Silva, Central CT Real Estate Broker Serving all equally (RE/MAX Professionals, CT 203-206-0754 ) over 2 years ago

Yep.  Always sideways, in my opinion, Ed.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Dryer vents should always be side discharge with a flap.  If the flap isn't flapping when the dryer is on, you've got a problem!

Posted by Stephen Weakley (Nationwide Mortgage Services) over 2 years ago

Once I had the vent flap hood sticking up, Stephen!  And I wondered how come it wasn't sitting open.  Turns out it was caulked shut!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

When I saw your diagram and read your description of it's placement, I thought you were talking about a rooftop bird house Jay Markanich .

What happens when a local flies by and decides to clog it with twigs and string; a warm home for the winter, that's what.   Never mind the bird droppings going down the vent tube into the dryer.

Posted by DEANNA EARLY - ( NMLS #268590 ), Virginia Mortgage Loan Originator (American National Bank and Trust) over 2 years ago

Bird nests do happen, Deanna, no matter where the dryer exhaust is located.  But still, the temptation needs to be resisted to cover the opening with a grill which captures lint.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

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