# Code on bathroom fan ducting type



## madmax718 (Dec 7, 2012)

I thought it was specially to slope down toward the outside, so that water vapor and condensation can be pushed out.


----------



## Tom M (Jan 3, 2007)

madmax718 said:


> I thought it was specially to slope down toward the outside, so that water vapor and condensation can be pushed out.


Yes it should be, SLS was calling out a discrepancy and poor enforcing decision.


----------



## kool9-99 (Dec 21, 2015)

I think the flex is allowed at the end of run.


----------



## A.W.Davis (Oct 17, 2006)

Rio said:


> Ask her to cite the code section...........


I did, she didn't know it off the top of her head.


----------



## A.W.Davis (Oct 17, 2006)

SLSTech said:


> Under IRC / IECC - nothing as many have stated
> Is there something in Title 24?
> 
> As for best pipe - personally I prefer PVC


Never tried PVC though I've seen it for tankless water heater venting. Looked pretty clean. 
I agree as well....I am thinking it is a title-24 requirement as well. :thumbup:


----------



## builditguy (Nov 10, 2013)

Tinstaafl said:


> If I have my druthers, I go out through a gable wall as first choice. That warm air going out through a soffit vent wants to rise, and a certain percentage of it will wind up back in the attic space if there's vented soffit.
> 
> I do agree that's usually better than a roof penetration, though.


You are right. When the warm moist air dumps out right under the soffit, there is a percentage of it that will be sucked back up through the soffit. I don't know how much. Probably not 100%. Of course it's not always humid air that is dumped out. Sometimes people use them to remove the humidity and sometimes people use them to remove smells.


----------



## Tom M (Jan 3, 2007)

AW I have used the "thin wall" pvc with a piece of insulated flex duct slid over it.


----------



## Mike-B (Feb 11, 2015)

For those using PVC, how are you connecting to the fan outlet and vent


----------



## Morning Wood (Jan 12, 2008)

I used insulated flex in my house. No problem with inspection or operation. In fact the fan will back draft the wood stove downstairs if not careful.


----------



## SLSTech (Sep 13, 2008)

Mike-B said:


> For those using PVC, how are you connecting to the fan outlet and vent


In some cases a regular PVC coupler will work for connecting to the fan (or you may be able to get a transition piece) --- same with the exterior, just pop the metal piece off & click the pieces together


----------



## Tom M (Jan 3, 2007)

Mike-B said:


> For those using PVC, how are you connecting to the fan outlet and vent


The short lengths come hubbed or swedged. The exterior side will pop on like the piece it came with.


----------



## 91782 (Sep 6, 2012)

Tom M said:


> The short lengths come hubbed or swedged. The exterior side will pop on like the piece it came with.


yup


----------



## Peter_C (Nov 26, 2014)

How many of you insulate the exhaust piping? 

I like solid smooth pipe screwed and taped, then insulated for condensation. Of course the flexible insulated pipe works, but rodents can and will chew right threw it...if present.


----------



## tjbnwi (Feb 24, 2009)

Peter_C said:


> How many of you insulate the exhaust piping?
> 
> I like solid smooth pipe screwed and taped, then insulated for condensation. Of course the flexible insulated pipe works, but rodents can and will chew right threw it...if present.


I insulate the vent pipes.

Tom


----------



## jlhaslip (Dec 31, 2009)

superseal said:


> Yea, there's no code violation, but I would urge you to use hard pipe over flex anyway as you get less drag and friction which maximizes fan efficiency.


I agree. The flex ducting allows for condensation to build up in the twirls and should be avoided, in my humble opinion.
Also, be sure that there are no "low spots" in the piping and there should be "positive drainage" to the exhaust end.

Remember that being code compliant is simply the minimum standard to which you can build. It doesn't cost much to improve on the minimum code requirements.


----------



## GettingBy (Aug 19, 2010)

jlhaslip said:


> It doesn't cost much to improve on the minimum code requirements.


Provided your improvements don't introduce new problems.

This "simple" venting seems to be pretty controversial.


----------

