Dryer venting and contact with wood

Dryer venting

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Dryer venting and contact with wood
« on: July 31, 2012, 09:22:47 AM »
I am trying to move my washer/dryer to a room above the garage.  The issue is the dryer venting.  I plan to build a 2x6 wall to allow electrical and water hookup with pipes etc installed from the garage up to the room.  The dryer venting is planned to go down (I have ordered and received the Dryerbox 4D unit) and along floor joist and existing through the soffit.  My issue is now some of the house structure between the upstairs floor joist and the soffit.  There is a restriction that reduces where I plan to run the vent.  It "squishes" to about 3.25 inches between a support and the roof decking.  This installation path also includes a small "up and over", not a continuous horizontal run.   I know the constriction and the "up and over" (about 20") are poor form, bu the run is fairly short.  My real question deals with fire hazards.  How big an issue is electric dryer ventwork coming into contact with wood, sheetrock etc.  In the floor joist above the garage I was planning on letting it rest on the sheetrock (garage ceiling).  The constriction was going to be implemented by squishing semi-rigid aluminum (I got from Dryerbox), but the vent would come into contact with the roof decking and a 2x4 support near the soffit.

A little more information.

The dryer vent will go down into a 4D the turn right for about 4 feet within the flooring, then moves into unheated/uncooled attic space before the "up and over" and then down through the soffit with a Lambro soffit dryer vent (another 11 ft in the attic). I plan to use rigid alum for the majority of the run with flex used within the 4D and to connect through the restriction to the soffit (about 3'). I hope to be able to disconnect at the soffit for cleaning puposes at that end.

Any information is appreciated.


John Rose
« Last Edit: August 15, 2013, 01:46:57 PM by rickharp »


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Re: Dryer venting and contact with wood
« Reply #1 on: August 09, 2012, 11:20:50 AM »
John, thanks for asking. 

There are two good questions in your post.  Here is how I interpreted them:

Can I use aluminum flex to wander through my tight up and over situation? 
The ICC building code does not allow the use the aluminum semi-rigid flex in any concealed spaces (walls, floor joists, attic or crawlspace).  For your situation, although likely convenient, the material thickness of the flex would further reduce the opening as you squish the hose, lessening the efficiency.  If you ever sold your home and the buyer’s inspector was observant, he may require that the semi-rigid pipe get replaced with hard pipe (rigid).  So, the rigid pipe is more efficient, safer and per code, but a bitch likely for you to make the configuration you need. 

Can the exhaust conduit touch the combustibles?
The code does not mention or require that the pipe maintain any separation from the wood studs, beams or drywall.  Generally the temperature does not get over 155 degrees in any of the pipe surfaces.  Taping the joints with the silver tape is a good practice to better contain any fire within the conduit.
« Last Edit: August 15, 2013, 01:47:09 PM by rickharp »
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