A Dryer Vent Through The Roof Is A Very Dangerous Thing

By
Home Inspector with Jay Markanich Real Estate Inspections, LLC 3380-000723
https://activerain.com/droplet/LXK

A dryer vent through the roof is a very dangerous thing.

I have written about dryer vents before, in many contexts.  Including through a roof!

But this one is so dangerous I have to reiterate my points.

I always prefer to see a dryer vent on the side of a house.  Even if it's high.

Why?

How do you know a dryer vent needs cleaning?  YOU HAVE TO LOOK AT IT.

How do you clean a dryer vent?  MANUALLY.

This dryer vent is NOT visible from the ground.  How do you know it needs cleaning?

With great effort.

This house leaves four choices to clean the dryer vent -

1.  A climb up in front and traversing a metal roof.  They can be slippery.
2.  A 40' ladder from the rear of the house, with another trip over the ridge of the house, negotiating fairly steep aspects up, over and down.  THEN you have to go back up, over and down the roof to get onto the top of a 40' ladder to climb down!  Yikes!
3.  Slither out a bedroom window, walk along a ledge on top of a metal roof, and climb up a fairly steep shingled roof 12' to get to this vent.
4.  Hire somebody!  And that would necessitate two people with a long ladder.  Not cheap.

That is all ridiculous! 

Look at this vent.  It is 100% clogged!  Someone has been up here before because I see roof tar above and beside the vent.  Is this the builder's "installation" job?  Did it leak and is this the "fix?"  The house is seven years old.  Has this vent ever been cleaned?

This roof is the third floor of the house.  The laundry room is on the first floor.  Looking at the house geography from inside the exhaust tubing servicing this vent goes straight up!  It is not accessible from inside the house.  I could not see it from the attic, so it is difficult at best to get at from inside there.

It must pass through a portion of the attic.  Is it insulated?

What happens when it snows deeper than 3"?  This vent is clogged even more!

In my opinion a dryer vent through a roof is less than smart.  How much less depends on its placement.

My recommendation:  all in all this is a dangerous vent, not just now but in the years to come.  How often should a dryer vent be cleaned?  When it's clogging!  I always look for the dryer vent on home inspections.  It is important to see where it is and if it needs cleaning.  We fortunately found this one, and only because I took a risk and went out a window to see if it was where I suspected! 

 

 

Posted by

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


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  1. Wallace S. Gibson, CPM 11/23/2012 07:37 PM
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Ambassador
1,323,760
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Jay that is a pet peeve of mine as well.  On my planet they are flat out not allowed on roofs.  I have seen them on 3 story houses where the roof has a 12/12 pitch----ridiculous.

Nov 23, 2012 11:08 PM #20
Rainmaker
2,772,675
James Dray
Fathom Realty AR LLC - Bentonville, AR
Exceptional Agents, Outstanding Results

I read a post earlier by Tom and although it did not have the same subject it seems Uncle Bob has been busy.  I don't know how he gets a contractors license for each State.

Nov 23, 2012 11:12 PM #21
Rainmaker
257,090
Vanessa Saunders
Global Property Systems Real Estate - White Plains, NY
From Manhattan to the Catskills of New York

Very good advice. I inherited a roof vent in my last house. My husband dreaded the semi-annual vent cleaning!

Now we have side vent...do it righjt the fist time if you can!

Nov 24, 2012 12:08 AM #22
Rainmaker
694,609
Clint Mckie
Desert Sun Home, commercial Inspections - Carlsbad, NM
Desert Sun Home, Comm. Inspection 1-575-706-5586

Hi Jay,

I have seen this a lot. My concern is here they don't use the proper vent, like the one in your picture.

A lot of times they want to use a simple can vent that gets the screen clogged with lint within a couple of weeks of use. Many run them out through the roof. I don't like it either.

Have a good day in Bristow my friend.

Best, Clint McKie

Nov 24, 2012 12:51 AM #23
Ambassador
1,153,501
Bryan Robertson
Los Altos, CA

This is a good advisory.  I just showed a condo with a vertical dryer vent and the home inspector advised having a close inspection of the vent to ensure it wasn't a fire hazard.

 

Nov 24, 2012 01:11 AM #24
Rainmaker
714,986
Olga Simoncelli
Veritas Prime, LLC dba Veritas Prime Real Estate - New Fairfield, CT
CONSULTANT, Real Estate Services & Risk Management

Sounds like sound advice. Wouln't a bulder be savvy enough to put the vent in where it should be, or do you think it was installed subsequently? What are the exact ramification of a blocked vent?

Nov 24, 2012 01:57 AM #25
Rainmaker
809,827
Evelyn Kennedy
Alain Pinel Realtors - Alameda, CA
Alameda, Real Estate, Alameda, CA

Jay:

Why in the world would a builder put the dry vent on the roof if the dryer is on the first level?  It makes no sense to me.  I'm off to check my dryer vent.

Nov 24, 2012 02:18 AM #26
Rainmaker
307,524
Pam Graham
All Real Estate Options - Jacksonville, FL
Jacksonville, Clay & St Johns Counties

I have never seen a dryer vent through the roof, only through the side. Maybe that means builders in my area used their head when constructing their homes. :)

Nov 24, 2012 02:35 AM #27
Rainer
28,992
Chris Cole
Coldwell Banker DRE# 01917703 - San Francisco, CA
Chris Cole

Hi Jay,

 

If you have two dryers and you turn one on and it blows hot steamy air into the other dryer but you don't see any air coming out of the vent on the side of the building. There is only one vent on the outside of the building. Does this sound like the two dryers share one vent to the outside and that is clogged some where between the outside vent and where the two lines intersect?

I have never seen anything like this before.

 

Thanks so much !

 

Great article.

 

Chris

Nov 24, 2012 01:08 PM #28
Rainmaker
1,820,496
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Andrew - that's a set up for a very inefficient discharge of the dryer!

Well, Christiansens, isn't it interesting how something that is really poorly thought out kind of becomes the norm?  Think ... the economy right now.

Lise - get on it!  Wow!  Never?  Oh, send photos!

Mike - you are asking me to get into the builder's head?  You talkin' to me?  To me?

Lyn - the better way is the way it used to be done!

Nov 24, 2012 08:59 PM #29
Rainmaker
1,820,496
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

It is Richie.  You are contributing!  That low vent makes it easy to clean too.

No, Gary, it's a big, big house!

S&L - real thought should be lent to the dryer vent placement, as you say.

Your world is a good one Charlie.  Was that vent through the 12/12 just under the receptacle for Christmas lights?

James - Uncle Bob has roots in every state and clime!

Nov 24, 2012 09:04 PM #30
Rainmaker
1,820,496
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Vanessa - not a fun thing to inherit!  I feel for your husband.

Clint - using the wrong materials and doing it the wrong way is the new wave, a real fad.

Bryan - with good reason.  What professional would you get to do that?

Olga - if you want me to explain builder thinking, I would have a hard time!

Evelyn - good thinking!  And clean it when it needs!

Nov 24, 2012 09:07 PM #31
Rainmaker
1,820,496
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Maybe Pam, or local regulations!

Chris - what you describe isn't good and probably a hazard.  Here is the code on exhaust vents sharing the same tubing:

 

The IRC is pretty clear on this (the underlining and bold are mine):
- M1501.1 Outdoor discharge. The air removed by every mechanical exhaust system shall be discharged to the outdoors. Air shall not be exhausted into an attic, soffit, ridge vent or crawl space.

That does not leave any room for any air to be pushed back into the living space by any other mechanical exhaust system.

Then the IRC adds this:
- M1507.1 General. Where toilet rooms and bathrooms and appliances are mechanically ventilated, the ventilation equipment shall be installed in accordance with this section.
- M1506.2 Recirculation of air. Exhaust air from bathrooms and toilet rooms and appliances shall not be recirculated within a residence or to another dwelling unit and shall be exhausted directly to the outdoors. Exhaust air from bathrooms and toilet rooms and appliances shall not discharge into an attic, crawl space or other areas inside the building.

That clearly states that exhaust air from the bathroom/toilet room/(dryer vent) shall be exhausted directly to the outdoors.

Based on the above two code sections, unless the installation instructions specifically state that two exhaust fans may be connected to a single duct, then two exhaust fans may not be connected to a single duct.

Nov 24, 2012 09:09 PM #32
Rainmaker
1,078,873
Sharon Alters
Coldwell Banker Vanguard Realty - 904-673-2308 - Fleming Island, FL
Realtor - Homes for Sale Fleming Island FL

Jay, we have many dryer vents going out the roof in our Florida homes. Ours goes out through the roof as well. We just cleaned it last year, and it definitely needed it. Our laundry room is in the middie of the house, so it's the only option.

Sharon

Nov 25, 2012 07:27 AM #33
Rainmaker
233,425
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

I agree, putting a dryer exhaust at the roof is poor practice.  That's a great way to prevent anyone from cleaning it.

Nov 25, 2012 10:20 AM #34
Rainmaker
1,820,496
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Well, Sharon, next time it snows deeply you will find that it clogs!

Reuben - not done regularly, for sure!  And in this case, it looked like never.

Nov 25, 2012 06:13 PM #35
Rainer
28,992
Chris Cole
Coldwell Banker DRE# 01917703 - San Francisco, CA
Chris Cole

Great thank you so much for taking the time Jay! Very Helpful.

Nov 26, 2012 10:33 AM #36
Rainmaker
1,820,496
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Thanks Chris.  I hope you can use the information.

Nov 26, 2012 06:27 PM #37
Rainer
28,992
Chris Cole
Coldwell Banker DRE# 01917703 - San Francisco, CA
Chris Cole

Just a quick follow up:

I found a crawl space between the dryers and the exteriror wall.

Sure enough the dryers were conect to each other by a T shaped fiting which was followd by about 6 feet of exra hose  curled on the ground, then a straight 5 feet up peice to the wall vent outside.

I had a 2nd vent installed and the 2 dryers now vent seperatley  with nice fitted hoses. 

They work fantastic and the hot steam is no long pouring back into the laundry room.

Thank you so much for all your help!!!

Chris Cole

Dec 07, 2012 02:59 AM #38
Rainmaker
1,820,496
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Glad it worked out for you Chris.  Very glad!

Dec 07, 2012 11:47 AM #39
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