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Bathroom Exhaust

Uncle Bob

Uncle Bob

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Joined
Oct 17, 2009
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Location
Texas
Well it looks like they have found a way to terminate the bathroom exhaust vents "directly to the outside" through the soffit overhang;

(right click on picture to enlarge)



and,



Here is a single. But they still don't understand that the duct material has to be listed for consealed location;



This type duct is not listed for consealed location.

Here is another bathroom exhaust duct that is not listed for consealed use;



This one was terminated into the soffit (not directly to outside the building).

I can't beleive they are still using this crap,

Uncle Bob
 
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Don't have much trouble with contractors using that stuff, but homeowners finishing their basements use it all the time. They go to the big box stores and buy a bath fan kit that comes with a hood and that vinyl crap, so of course the question usually is "If I can't use it, why do they sell it?" No mechanical codes outside the city limits here.

For soffit terminations, I have seen rectangular shaped caps complete with backdraft dampers. The assembly protrudes down from the soffit about 1 1/2". They seem to work well.
 
Why would you vent moisture laden vapor into a vented soffit where it can enter back into the attic? If it's not a vented soffit, how are they ventilating the attic?
 
Inspector Gift said:
"...Although we were supposed to use metal pipe, almost all of us remember the flexible white plastic dryer vent hose kit sold in hardware stores. As it turns out, these combustible white plastic hose kits are deadly when improperly used as dryer venting and are the reason for many dryer vent fires. However, until recently they were still commonly sold as dryer venting.It was not until December 2006 that Underwriters Laboratories established UL 2158A “Clothes Dryer Transition Duct” which is an approved standard for flexible high temperature exhaust duct rated to 430 degrees Fahrenheit, that can also be used on both electric and gas dryers.

Now be careful. When you go to the hardware store you may see flexible duct with a UL listing of UL 181B “Closure Systems for Use with Flexible Air Ducts and Air Connectors” however this standard is for flexible plastic and metal heating and cooling ductwork and vent fans such as in your bathroom. This standard UL 181B and these products are not for use as a dryer vent. Only flexible ductwork meeting UL 2158A can be used as dryer venting.
Click to expand...
From the old BB
 
Confused here. Sooo, the pvc and metallic flexible duct shown in the pictures are not approved for bathroom exhaust?
 
Greg,

" Sooo, the pvc and metallic flexible duct shown in the pictures are not approved for bathroom exhaust? "

Correct; not listed for use in consealed location. But, unfortunately, most jurisdictions allow them anyway.

Uncle Bob
 
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dcspector said:
Confused here. Sooo, the pvc and metallic flexible duct shown in the pictures are not approved for bathroom exhaust?
Click to expand...
Not necessarily true, The quote I posted is for “dryer vents”. Several years ago it was discovered that the tubing had problems. The corrosion and degradation, due to moisture, of the metal and plastic pipe need to be considered. Is the pipe used listed by a testing agency, and is it tested for the application it is used for?
 
Thanks Mark. Yes I have been aware of the Dryer exhaust for years but Bath exhaust has me a bit confused with Bob's post.
 
UB...Wow! Can you send me that info? I have been passing this duct for bath exhaust in an accessble attic and in concealled locations as in through ceilings which ouch that is concealed. Thanks UB
 
Greg,

I'll post it here; so, if I make a mistake someone can correct me and you won't go off with bad information. It's a little lengthy, for right now; but, will post it soon.

Uncle Bob
 
UB,

Some flex ductwork is LAL for concealed locations at any length. Flexible dryer connectors cannot be concealed but there are lots of products that can be used for bath exhaust, hvac supply air etc. and can be concealed. Some can be concealed but have a max. 14' run. It all depends on the LAL of the product.

Most bath fans also have a damper built in so you don't need the damper at the termination cap. We allow fans to terminate in the soffit if they terminate in an approved cap. Not a good idea but the code does not prohibit it.
 
Well, I can't find it in my boxed stuff. I'll call my old BO tomorrow and ask him where the information is. Maybe I'm just getting old and losing it.

Sheesh,

Uncle Bob
 
I slept on it for a few hours; and I think Mark Handler and Daddy-O are correct.

I can't find, what I thought was a regulation that these two type ducts could not be used in concealed space.

I've just been out of the field too long.

Here is a link to Dundas Jafine; a major duct manufacturer;

http://www.dundasjafine.com/products/31-semi-rigid/79-semi-rigid-aluminum-duct.html

2006 IRC, M1601.2 Factory made air ducts or duct material shall * be approved for the use intended.

I believe, that because we had so many problems with vinyl and flexible aluminum foil ducts in attics and concealed chases; that my Building official discontined * approving them for that use. After over two years, I just remembered that they could not be used in our jurisdiction.

I would suggest that in factory fireplace installation; you check the manufacturers instructions and see if they don't require; at least; semi-ridged duct for their combustion air;

Here are some pictures I took Sunday in Moore, Oklahoma.

The first is a combustion air duct for a factory made fireplace; note the hole that will be consealed when the termination cap is secured;

(right click on picture to enlarge)



and,



Here is one that was started from the fireplace with semi-ridged and then they used tape only to secure it to flexible aluminum. The tape is affected by temperature changes and will fall off; causing the lower duct to fall away from the the upper one. I've seen this many times before the BO stopped allowing the use of tape only (requiring screws to secure the joint (on combustion air only);



Glad I post here instead of PMing you, Greg. The gang; as usual; kept me from putting out mis-information.

Thanks Ya'll,

Uncle Bob
 
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Famous last words:

"Check is in the mail."

"I did not have sex with that woman."

"The holocaust never happened."

"What's the problem, it's UL listed?"
 
Mark,

"

quote_icon.png
Originally Posted by TJacobs

Famous last words:

"What's the problem, it's UL listed?"

"If it is installed per the listing"

UL makes mistakes; doesn't cover all situations; and the Building Official is the "Approving Authority"; not UL.

2006 IRC, M1601.2 Factory made air ducts or duct material shall be approved for the use intended.

Chapter 2 Definitions: Approved. Acceptable to the Building Official.

Uncle Bob
 
Thanks for clearing it up... the fire place is probably an incorrect application of the flex duct... as is dryer duct.
 
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