Code help for Dryer duct

Mike Bossen · 07-01-2007, 07:49 PM

Found a dryer vent duct routed into bedroom closet then out to the exterior wall. This looks to be a DIY job and was such written up as improper installation and fire hazard. However, the buyer would like to get some code references to the proper installation. Any help is greatly appreciated.

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**John Arnold** · 07-02-2007, 04:09 AM

I didn't see anything in the 2006 IRC clothes dryer section that would forbid this, unless the manufacturer does, for some reason.

Mark Nahrgang · 07-02-2007, 05:23 AM

I don't see why it's a problem. It's a metal duct. I have a "standard" comment that I put in virtually every report to be sure to keep it clean. Other than it taking up closet space I'd not even mention it.

**Phillip Stojanik** · 07-02-2007, 06:40 AM

What is the overall developed length of the pipe run? Is that a sheet metal screw I see in the piping at the bottom elbow? Are all of the joints sealed with an approved duct tape (bottom elbow again)? Have the pipe joints been made in the direction of flow?

I can't really tell enough from the photo but any one of these could be a potential problem from a code/fire hazard perspective.

Even outside of the code it would be fair to say that it is not a "standard and customary practice" to run a dryer vent through a clothes closet.

**BARRY ADAIR** · 07-02-2007, 07:37 AM

Mike,

Try the archives

Dryer vent - Home Inspection & Home Inspector Services For Inspections and Inspectors

or this
Dryer Venting Guidelines - How to avoid dryer fire hazards

**Jerry Peck** · 07-02-2007, 07:58 AM

Nothing prohibits that, however, your client will want to protect that from physical damage by installing some type of protective chase around/over it.

Code is minimum, not common sense.

As others have stated, make sure the male end is inserted in the female end in the direction of flow - no ridges which may collect or catch lint are allowed. Neither are screws.

Remove that "ducK" 'ducT' tape and use real "duct" tape on those joints before installing the chase over it.

Mike Bossen · 07-02-2007, 04:48 PM

Thanks for all of the input from everybody. All of the problems that were mentioned in the replys were addressed in the report and the buyer is planning on complete removal of this setup and re install in a more appropriate location. The buyer was just hoping to find some code references to help with negotiations but does not sound like the codes specifically address installation such as this. No matter, as it will be corrected regardless. Thanks again for the input.

**Jerry Peck** · 07-02-2007, 04:53 PM

Mike,

You will frequently find that code does not address stuff you find, because 'code' is only addressing *the minimum crappiest way one is legally allowed to do things*, no worse.

'Building to code' just means the builder is building 'crap'.

Richard Rushing · 07-02-2007, 06:47 PM

Originally Posted by Jerry Peck

'Building to code' just means the builder is building 'crap'.

Soooooo... when we have minimalist inspectors (SOB) it just means that they are inspecting like crap.

Rich

**Chris Roth** · 02-20-2010, 03:30 PM

I know it is an old post but the picture says a thousand words. The installation is incorrect of what i see. Duct Tape? Fire hazard bigtime! Please look at the 2009 International Mechanical Codes and the 2009 International Residential Building Codes when Inspecting. Nice Post!

Chris Roth
Dryer Vent Wizard
Brownsburg, IN

**Jerry Peck** · 02-20-2010, 05:21 PM

Originally Posted by Chris Roth

I know it is an old post but the picture says a thousand words. The installation is incorrect of what i see. Duct Tape? Fire hazard bigtime! Please look at the 2009 International Mechanical Codes and the 2009 International Residential Building Codes when Inspecting. Nice Post!

In looking at that photo again (and without re-reading the posts above it) I have to wonder where the dryer is:
- a) is the dryer to the left?
- b) is the dryer on the other side of that wall?

It makes a BIG difference.

chris mcintyre · 02-20-2010, 06:07 PM

Originally Posted by Jerry Peck

It makes a BIG difference.

Why?

**Jerry Peck** · 02-20-2010, 06:14 PM

Originally Posted by Jerry Peck

In looking at that photo again (and without re-reading the posts above it) I have to wonder where the dryer is:
- a) is the dryer to the left?
- b) is the dryer on the other side of that wall?

It makes a BIG difference.

Originally Posted by chris mcintyre

Why?

The direction of flow of air and the direction of the fittings.

The air must flow with the fittings so there are no facing ledges or edges to trap lint as there would be with the direction of the flow against the fittings.

- M1502.5 Duct construction. Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.

chris mcintyre · 02-20-2010, 06:22 PM

Originally Posted by Jerry Peck

The direction of flow of air and the direction of the fittings.

The air must flow with the fittings so there are no facing ledges or edges to trap lint as there would be with the direction of the flow against the fittings.

- M1502.5 Duct construction. Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.

OK, got it, wasn't think about the fittings,

I thought it might have something to do with the pipe up the wall.

**Bob Harper** · 02-20-2010, 06:57 PM

I still have a problem with the information from that site where it shows you how to damage and deform flexible transition duct for dryer venting. First of all, as soon as you crush the corrugations, this duct tends to unlock its seams and come apart. It also crushes any warranty and listing. BTW, transition duct must be listed to UL2158A, which most are not. You would have to get clear written permission from the mfr. that their duct is approved for ovalizing, by what means, up to what aspect/ ratio and how to attach it. Most importantly of all, to date, nobody has shown me how to attach a flexible transition duct without violating the male end downstream requirement. Also, when you ovalize a duct, you reduce the flow capacity. Corrugated ducts themselves reduce flow capacity about 20% over smoothwalled duct when round but routed straight. If you make a lot of bends in flex snaking around, you reduce flow capacity even further. FYI, you would need to ovalize a 5" round duct into a 4" minimum dimension just to equal the cross-sectional area of a 4" round. If they ovalize to 3.5" for a stud cavity, that 5" ovalized is right at the limit. BTW, you may need strike protection for ducts in wall cavities.

Now, if someone could come up with a listed transition for flex that maintained a male end downstream, then I'd say you have a code compliant product. Until then, I don't see how any flex is legal.

BTW, where's the support for that rigid duct in the original pic and where's the sealing per the energy code/ weatherization requirements?