# Bathroom Attic Fan vented to Attic. Damage?



## jdm001 (Nov 6, 2009)

I have a bathroom fan that vents straight up into our tiny attic. The attic is only 3 1/2 feet high at it's highest point down the center, and stuffed with insulation... So viewing inside of it is impossible. The attic has an opening on both the north and south sides, so wind does blow air through.

Two questions:

1) Can there be damage in the attic, as it appears to have been this way for a while? Is there possibly mold (I didnt smell anything up there)?

2) When I cut a whole into the roof to vent (impossible to get to soffit, I can only fit 1/2 way back and the slope is less than 18" for me to crawl more), is there anything I should be aware of?

Thanks!


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## sciron (Jan 8, 2011)

jdm001 said:


> I have a bathroom fan that vents straight up into our tiny attic. The attic is only 3 1/2 feet high at it's highest point down the center, and stuffed with insulation... So viewing inside of it is impossible. The attic has an opening on both the north and south sides, so wind does blow air through.
> 
> Two questions:
> 
> ...


It's really bad to have moisture from your bathroom fan going into your attic. Not only can the moisture soak your insulation reducing it's effectiveness, but it can also cause electrical problems with your wiring if the moisture collects on the inside of the roof and drips down onto any wiring. It's an easy fix to cut a hole into your roof and install a vent. Once you're on your roof you'll have access to your fan and can install your ducting. I did mine and it's an easy afternoon project.

Good Luck


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## gregzoll (Dec 25, 2006)

There can, especially if the moisture can not leave the space. If you can get a good roofer to add a roof vent for the attic vent, that would be the best way, or vent out of a sidewall or sofitt.


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## algored2deth (Jan 7, 2011)

jdm001 said:


> I have a bathroom fan that vents straight up into our tiny attic. The attic is only 3 1/2 feet high at it's highest point down the center, and stuffed with insulation... So viewing inside of it is impossible. The attic has an opening on both the north and south sides, so wind does blow air through.
> 
> Two questions:
> 
> ...


If you don't see mold or any funny discolorations, I would suspect no damage. 

Make sure to vent through the roof and not the soffit. Going through the soffit (provided it is ventilated correctly) can just cause moisture to possibly re-enter your attic. 

Use rigid duct/piping. Don't use that accordion hose. Also make sure to seal any joints on the ductwork and use insulation to wrap around it to prevent condensation from running back down into your bathroom. Also make sure that your fan housing box has been caulked/spray foamed so that heated air does not leave your home where it comes through the ceiling.


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## jdm001 (Nov 6, 2009)

algored2deth said:


> Use rigid duct/piping. Don't use that accordion hose. Also make sure to seal any joints on the ductwork and use insulation to wrap around it to prevent condensation from running back down into your bathroom. Also make sure that your fan housing box has been caulked/spray foamed so that heated air does not leave your home where it comes through the ceiling.


Thanks everyone, really appreciate the help!

Algored, why not use the corrugated accordion style? I know the ridges make the air flow less efficient, but as long as it vents should I care? Is there another reason?

Not to cut corners, but I literally only have about 2 feet of clearance in the attic, and I'll be doing this on my back... so messing with elbows and joints will me impossible I think.

I *might* be able to if I preassemble and guess at the length, so I can try if there's a big reason to do so. Can you let me know if you think it's necessary for my situation?


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## algored2deth (Jan 7, 2011)

The corrugated stuff is just more restrictive. The rigid piping is also easier to insulate. If it is such a short run, then it may not matter that much. Just get the insulated version and you will be fine.


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## suprvee (Sep 2, 2010)

algored2deth said:


> If you don't see mold or any funny discolorations, I would suspect no damage.


This. I had my kitchen exhaust vented into my attic for about 15 years (one of the previous owners did some cowboy remolding). The only damage was to the insulation, which smelled like bacon. My attic is only 4' high, but has good ventilation.


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## Malibujim (May 5, 2009)

I installed a vent fan in our bathroom a couple years ago, and not wanting to go thru a shake shingle roof, I went thru the attic wall and installed one of those things for dryer vents with little shutters. Works good, but you don't always have an attic wall nearby either.


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## jdm001 (Nov 6, 2009)

Thanks to everyone who posted help, I need to call on you all again please!

So I went to fix this and I found that the bathroom fan vented into the attic like I had thought, but, when I got up there I was surprised.

It vents directly under one of those weird turbine vents on the roof (I included a pic of a new one for reference), literally three feet directly under it, but no duct hosing or anything.

1) What does that style roof vent do? I can see slight slivers of daylight in it, and there's no ductwork, just a big 8 inch circular hole with that turbine on top.

2) So how do I now vent the bathroom fan. It would look silly having a small vent six inches from the turbine vent. 

I can probably make or find a way to shrink the 8 inch opening to go down to a three inch for the bath fan exhaust. Would closing that vent off to the rest of the attic (there's another "turbine vent on the other side of my small ranch house).. would it hurt airflow?


Please help with advice, and again thanks in advance!


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## jdm001 (Nov 6, 2009)

So I did some reading on roof vents, and it appears these are good for my roof to pull air without any electricity! But my question is, can I just install the new bath fan and nail the edge of the duct inside the larger opening for the roof vents. 

I know it would partially block about half of the vent for the roof, but it would also directly exhaust out the moist air from the bathroom up into the turbine of the roof sucking it away. 

Is this correct, is this the best way to do this ?


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## jankencanada (Jul 23, 2010)

*Vent to Roof Turbine*

That's what I did many years ago. Checked it often since. No sign of trouble.
Did insulate the 6 inch vent pipe. My attic is 9foot high at the ridge. Ken


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## Ron6519 (Mar 28, 2007)

jdm001 said:


> I know it would partially block about half of the vent for the roof, but it would also directly exhaust out the moist air from the bathroom up into the turbine of the roof sucking it away.
> 
> Is this correct, is this the best way to do this ?


This is not correct or the best way. 
Ron


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## algored2deth (Jan 7, 2011)

jdm001 said:


> So I did some reading on roof vents, and it appears these are good for my roof to pull air without any electricity! But my question is, can I just install the new bath fan and nail the edge of the duct inside the larger opening for the roof vents.
> 
> I know it would partially block about half of the vent for the roof, but it would also directly exhaust out the moist air from the bathroom up into the turbine of the roof sucking it away.
> 
> Is this correct, is this the best way to do this ?


I would say no. I think you are going to have to make a new hole in your roof, put in a correct vent, run a couple elbows with rigid insulated pipe, and vent through that new spot. Not a good idea to vent humid air through a vent not made for it. You have no guarantee that the vent is spinning continuously anyways. Your project has just gotten harder. There is a video or two over at askthebuilder.com that shows how to do the install. Not hard to do.


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## jdm001 (Nov 6, 2009)

algored2deth said:


> I would say no. I think you are going to have to make a new hole in your roof, put in a correct vent, run a couple elbows with rigid insulated pipe, and vent through that new spot. Not a good idea to vent humid air through a vent not made for it. You have no guarantee that the vent is spinning continuously anyways. Your project has just gotten harder. There is a video or two over at askthebuilder.com that shows how to do the install. Not hard to do.


Algored: Is there any problem using about 3-4 feet of that flexible stuff, and then making a new hole approximately 2' from the fan (and about 1' from the top of the ridge)? I can move it sideways more, but no matter what i do, there's just not enough room to work with the rigid duct and put in elbows in that tight of space.


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## algored2deth (Jan 7, 2011)

Not a big fan of the flex stuff but sometimes you got do what you got to do. If you were going to run 20' of the stuff then that is a different matter. It is when you take long runs of the stuff and let it sag and have areas where debris can collect in little valleys. It reduces flow rate, yadda yadda yadda. There is flexible aluminum out there as well I believe. Check into that because it may work. Not sure on how tight you can make a radius with it though. You will probably be ok. I am sure if others are reading this and think otherwise, they will chime in. 

dennis


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## PatrickGSR94 (Mar 2, 2011)

I need to do this for both of my bathroom fans. Unfortunately it is VERY common around here for bathroom fans to vent into attic spaces, even on brand new construction. I really don't know how it passes inspection.


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## Ron6519 (Mar 28, 2007)

If you use the insulated duct and keep the turns as sweeping turns with a large radius, you should be fine.
Ron


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## Malibujim (May 5, 2009)

I just put a vent fan in our master bath a couple weeks ago and used the aluminim flex tubing. It's a lot better than that vinyl flex tubing made for dryers. Although flexible, it is fairly smooth walled inside, and more rigid than the vinyl ducting. Again, I went thru the attic wall to vent outside.


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## Ron6519 (Mar 28, 2007)

Malibujim said:


> I just put a vent fan in our master bath a couple weeks ago and used the aluminim flex tubing. It's a lot better than that vinyl flex tubing made for dryers. Although flexible, it is fairly smooth walled inside, and more rigid than the vinyl ducting. Again, I went thru the attic wall to vent outside.


"It's a lot better than that vinyl flex tubing made for dryers." 
Vinyl flex tubing should never be used for dryers. It's flammable and it's against code.
Ron


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## pyper (Jul 1, 2009)

jdm001 said:


> So I did some reading on roof vents, and it appears these are good for my roof to pull air without any electricity!


Too bad they don't really work.

I'd probably use that opening and put your duct through it, with an appropriate top.

If your attic needs ventilation, then put in something appropriate. Maybe a turtle shell style fan in place of the other one. Or a gable fan.


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## 95025 (Nov 14, 2010)

jdm001 said:


> Thanks to everyone who posted help, I need to call on you all again please!
> 
> So I went to fix this and I found that the bathroom fan vented into the attic like I had thought, but, when I got up there I was surprised.
> 
> ...


Those turbin attic vents are made to spin when the wind blows. In theory they suck air up and through them when they're spinning. In reality, they just allow air to flow through them. Either way, they're alright.

Having your bathroom fan vented directly under this turbine vent is not exactly ideal, but it's not horrible either. Warm air rises, so the warm wet air will - for the most part - go right up and out of the turbin.


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## Ron6519 (Mar 28, 2007)

DrHicks said:


> Those turbin attic vents are made to spin when the wind blows. In theory they suck air up and through them when they're spinning. In reality, they just allow air to flow through them. Either way, they're alright.
> 
> Having your bathroom fan vented directly under this turbine vent is not exactly ideal, but it's not horrible either. Warm air rises, so the warm wet air will - for the most part - go right up and out of the turbin.


I was under the impression that the turbine fans would spin as the hot air passed through it, creating it's own motion. The wind would help, but wasn't necessary.
Ron


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