# Second Story Bathroom Vents Not Ducted Outside



## papakevin (Dec 18, 2014)

I recently purchased an older home out in the country so the wife could have some chickens and a garden (happy wife, happy life).  

I'm learning that the overall construction of the property is suspect and finding a bunch of little items which bother me. One of those is the fact that the two upstairs bathroom vent fans aren't vented outside and vent directly into the attic.  There are the usually roof vents in place, but I don't like having the bathroom moisture vent directly into the attic. We live in southern Indiana, so the winters get cold and I like to take long hot showers in the morning to warm up. 

Any best practices on the best way to  run venting for the bathroom fans?  Would there be an issue with back pressure if I had both running into a T so they could vent out one pipe?  Is a roof vent the best option or should I look at something else?  

I had heard it is somewhat common to have bathroom fans vent up into the attic, but this seems troubling to me. Am I making a big deal out of something which is ok as is?  Let me know your thoughts.  Thanks. 





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## inspectorD (Dec 18, 2014)

Yes venting into the attic is always an issue. Vent each fan separately through the roof, and adding an insulated  pipe to the scenario is not a bad idea.
Keep it simple , and away from any valleys.
Good luck on your new house..with a Happy wife.


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## nealtw (Dec 18, 2014)

Yes, what he said.


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## frodo (Dec 18, 2014)

to add to the answer.   exhaust/plumbing  vents SHALL be.  minimum 10'  from an operable window or fresh air intake

here in mississipi,  common for bathroom fans to vent in attic. 99.9% of them do


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## beachguy005 (Dec 18, 2014)

Here's my take on venting.  I prefer to vent through a soffit rather than through the roof.  My logic...such as it is, is when you go up through the roof, you need to put a hole in your roof and that's just another place for a water leak. Also gravity.  When you're forcing air up, it needs enough force to open the damper.  You also have an issue with drain back.  When you shut off the fan any condensation still in the duct runs back down, potentially into the fan housing.
Through a soffit and you'll never have to worry about a water leak, you have gravity to assist in opening the damper and a downward pitch will drain any condensation out the vent.
Obviously if the bath is in the middle of the house that needs to be considered but most are on the outside and near a soffit.


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## oldognewtrick (Dec 18, 2014)

Beach guy, I understand your logic, the problem is that when air is discharged from the vent, it is sucked back in through the soffit vent and you end up with moist air still in the attic. A properly installed roof vent will not leak.


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## beachguy005 (Dec 18, 2014)

Not everyone has vented soffits and I don't buy that anything vented out of a soffit will just be sucked back in.  We're talking about an exhaust fan running only briefly.  I agree that a properly installed vent won't leak but that's when installed properly and when it's first installed. You also have potential blockage with any snow loads or freezing from sleet.


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## frodo (Dec 18, 2014)

beachguy005 said:


> Here's my take on venting.  I prefer to vent through a soffit rather than through the roof.  My logic...such as it is, is when you go up through the roof, you need to put a hole in your roof and that's just another place for a water leak. Also gravity.  When you're forcing air up, it needs enough force to open the damper.  You also have an issue with drain back.  When you shut off the fan any condensation still in the duct runs back down, potentially into the fan housing.
> Through a soffit and you'll never have to worry about a water leak, you have gravity to assist in opening the damper and a downward pitch will drain any condensation out the vent.
> Obviously if the bath is in the middle of the house that needs to be considered but most are on the outside and near a soffit.



Broan makes a roof vent for exhaust fans with out a damper
logic being,  the bathroom fan already has a damper so a second is not needed
properly installed with the insulation kit,  it is not a problem.

if a pipe is run up to a soffit or a roof vent the condensation will be the same
not an issue if pipe is installed correctly

install as first directed by Inspector D.    no problems


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## nealtw (Dec 18, 2014)

If and you should have vented soffet and you run the vent out there, change six feet of soffet to unvented, as long as that dosn,t close all the venting in the soffet your good.


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## GBR (Dec 20, 2014)

Extra moisture in an attic is never good. Many good points given, I will add my thoughts. Insulate, as said and more importantly; vapor barrier plastic wrap (FG is not a vapor/air barrier) the ducting. Run straight/smooth pipe (no 45's) rather than flex (if flex, use one size larger for long runs to make up for the lower pressure due to turbulence from ridges (which collect moisture, same as a roof vent which drains back in attic/pipe from changing direction - as a "turtle") compared to *gable end vent-(my choice)*, pitched to drain with multi-louvers outside (against freezing shut). If using a termination damper - always good idea to keep the pipe warmer with dead air rather than exterior air admittance- which gives instant condensation in cold climate), install it for dripping out. Two in one is fine, check local AHJ. While there, check local code as many site only 3' from windows; http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_15_par022.htm?bu2=undefined

Tell us the intake/exhaust vent sizes/numbers and attic square footage and we can figure if you should/could close some soffit vents to exhaust there...
Gary


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## Floridagal (Dec 20, 2014)

This is something we are in the process of figuring out the best way to install, all 3 bathrooms need vents&#8230;.the roof is metal so not too sure about going through the roof. I'm sure if done properly there shouldn't be a problem with possibly causing roof leaks in the future.


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## frodo (Dec 20, 2014)

my self,  i would run them to the soffit vent. not the roof
>>>OR>>>  out the side of the house.

http://www.homedepot.com/p/Builders...cm_mmc=shopping-_-shopzilla-_-D30-_-100673366


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## GBR (Dec 20, 2014)

Forgot my link to "not soffit- if active vents there;
"M1501.1 Outdoor discharge.
The air removed by every mechanical exhaust system shall be discharged to the outdoors in accordance with Section M1506.2. Air shall not be exhausted into an attic, *soffit*, ridge vent or crawl space.
" from; http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_15_sec001.htm

Bold is mine, Gary


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## beachguy005 (Dec 20, 2014)

You can't vent into a soffit but you can vent through a soffit.  You can't vent into an attic or crawl space but you can vent through them.


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## frodo (Dec 20, 2014)

beachguy005 said:


> You can't vent into a soffit but you can vent through a soffit.  You can't vent into an attic or crawl space but you can vent through them.




100% correct


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## papakevin (Dec 20, 2014)

Great information guys, I really appreciate it. I'd love to go through the side of the house via the soffit vs the roof, but that side of the house is the walkout basement, first floor has 10' ceilings and then the second floor, so it's really high. Will look at both options and figure which one I want to tackle. Good news is both bathrooms are on the same outside wall, so it won't take much to get there. 



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## frodo (Dec 21, 2014)

i know what the code says.  but i would never,  never ever.  put a plumbing vent as close as 3"  from a window

that is asking for a call back,  on a still , day,  funk will settle , funk is funky


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## slownsteady (Dec 21, 2014)

frodo said:


> i know what the code says.  but i would never,  never ever.  put a plumbing vent as close as 3"  from a window
> 
> that is asking for a call back,  on a still , day,  funk will settle , funk is funky



That would be true for the plumbing vent stack. Not so much for a bathroom moisture vent.


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## GBR (Dec 21, 2014)

I understand venting an attic is mainly to remove excess moisture, but why would one vent a bathroom fan in an active passive soffit.... the moist air will catch in the positive air stream coming up the side of the house from across the ground. Wintertime a house attic is under air pressure from the stack effect and any interior mechanical running. Then the air from the bath would deposit any moisture present on the roof framing, to mold/rot. Summertime- the stack effect reverses; in a house without AC, many open a window on the top floor wrongly thinking they are venting the warm air, but are letting (bath) air back in if close to a window; http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_15_sec006.htm  Sited again- still exhaust vent and still 3 feet not inches....

Especially when the soffit vents should be located in every rafter bay to wash the complete roof (balancing the ridge vent), any holes plugged/missing/restricted will affect the complete system, or the very least- leave an attic area unvented.   Papak, see if you can get a few pictures that would help.... Gary


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## nealtw (Dec 22, 2014)

Gary, where I am the soffet always goes back to the house level which makes a common area above the vented soffet so closing some of it would not have a bad effect. But you are right when the soffet follows the angle of the rafters, you would be closing the needed venting and then thru the roof would be the way to go.


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## beachguy005 (Dec 22, 2014)

I lived in MA, on the coast, in a 2 story house.  The house had a ridge vent and soffit vents that I installed when I removed the gable vents.  The reason I removed them was that regardless of the type of vent, I would get wind driven snow forced into them, especially during a 2 day noreaster.  The snow would eventually melt and soak the insulation and ceiling.  The ridge vent worked well.
The bathroom was on the north side of the house on the second floor and when I vented it, I wasn't going through the roof because the snow would block any vent.  
Installing it in the soffit worked perfectly.  Used that fan sometimes twice a day, most of the year, for years on end.  Checking the attic for mold....never found any.  This whole concept that your attic is going to just suck up any moisture or air that gets exhausted and create issues is nonsense.


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## frodo (Dec 22, 2014)

beachguy,  the code is written because these things CAN happen.  Not that they WILL happen in every house on every instance.

your house in Maine,  did not retain moisture.  Thats a good thing.  Your neighbors house might have.

the code is written to incompus all aspects and scenero's  .  

I myself have seen fart fans in the attic, no mold, no moisture

I have also seen mold and wet insulation.    just depends where,  and how  it is done


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## beachguy005 (Dec 22, 2014)

It doesn't say you can't vent through a soffit.


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## nealtw (Dec 22, 2014)

I beleive it says when venting thru the soffet, solid soffet for three feet either side of the vent.
To many variables to figure how a certain house will react.
Prevailing winds, temp. in the attic compared to outside air, amount of heat coming off the top of the wall and how much air that draws, how well the roof vent system works and speed of the air coming from the vent and where the moisture condences and time of year.
I had this discussion years ago so I started watching houses down the hill when the fans are running. It is only visible in the winter when it is dark for the most part with a light on in the bathroom you can see a fog. One day it will go straight down a slowly work around the side of the house and other days it will slowly drift up and over the gutter. Other times it must condence right away as you see no fog.


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