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Old 11-23-2013, 11:00 AM   #1
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Bathroom fan venting in attic

Bought a house a few months ago with three bathrooms that was built 40 years ago. The two baths on the top floor are vented directly into the attic, which I know isn't good.

From what I have read online, I know that the best route would be straight up the the roof and put in 2 new vents. I am concerned, though, as a diy-er about putting 2 more holes in the roof, especially now with the weather colder here in Chicago and the shingles more brittle than summer.

I am wondering about using 25 feet of flexible insulated ducting:

...and bring it from the fan to this in the roof (there are 2 of these - one each direction from fans):

I have ridge vents along the peak of the roof, so I have been told that this would not be a problem with airflow in the attic.

IF this is acceptable, some other questions about installing:

One big box guy in plumbing said to bring the duct close to the opening in the roof where the vent is and let it flow out. The big box guy in building supplies said not all the exhaust from the fan will go out, so maybe I could use this...

...and staple over the hole and put the duct into it so that it will all go out. Will this work? Would this leak condensation to floor of attic?

As far as a path from the fan to the vent (IF it is viable), what would be best: a straight line from fan to vent sloping up (which would be a challenge with the joists):

...or perhaps straight up to where joists meet roof (see last pic), and then across joists until below vent area, and then over to vent? That way would give at least one 90 degree turn right above where fan is, though.

Thanks for all insights!


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Old 11-23-2013, 11:49 AM   #2
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The big box store advice is so wrong. Each fan should have it's own vent.

Something like this, not necessarily the kit.


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Old 11-23-2013, 12:28 PM   #3
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so, I am better off waiting until spring when it is warmer, and doing it straight up with that kind of vent? It's been this way for 40 years, I guess one more winter will be okay?

I was just worried about the shingles cracking with the cold and having 2 more holes in the roof to be concerned about.
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Old 11-23-2013, 12:44 PM   #4
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Or you can go through the wall if you have a gable end.
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Old 11-23-2013, 01:09 PM   #5
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I would wait til spring. Remember, you have to get on the roof and do some roofing work so your boot covers properly shed water. Shingles will be brittle, roof could be slippery, etc.
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