Bathroom Fan Venting - through garage?


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Old 03-15-12, 08:51 PM
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Bathroom Fan Venting - through garage?

We're remodeling the downstairs bathroom and I want to install a fan for the sake of everyone

Of course this is the one part of my house where the joists above run perpendicular to where I'd want the vent pipe to go outside, and drilling a 3 or 4" hole is probably not a fantastic idea in 2x8's.

What I was thinking:

- flex duct 5 ft through the ceiling into the garage (open bay parallel to joists)
- connect it to a PVC 90degree elbow where it pops out in the garage
- run PVC along the wall and pop outside

total run is ~ 5ft of flex inside, and 6ft of PVC in the garage to the outside. probably have the PVC slightly sloped down in the garage to the outside? Since I can just shove a 5' piece of PVC into the ceiling from the garage, I can probably do without flex if it's better off.


Let me know if this makes sense to everyone, or if there is a better way to accomplish this task.

Thanks!
 
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Old 03-16-12, 07:53 AM
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Why use flex at all? Once the hole is drilled you should be able to put the duct right into the open bay. And I'm not sure PVC is a good idea either. Just use the metal duct.....both for airflow as well as fire safety. You'll need to use the fireproof sealant at the wall penetration.

This is assuming the Pros here can say if it's even allowed.
 
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Old 04-12-12, 08:44 PM
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I got a chance to open up the ceiling, found water pipes and a drain right above the existing light.

I moved over one bay and it's open to the garage wall above.

Since I can't go straight to the outside wall because there are 4 joists in the path, is it safe to drill a 4" hole in the 2x10 above the bathroom/garage wall (the end 2x10 that all the 2x10 joists nail into)? I see a 2 or 3" PVC drain pipe for the shower above coming out of the same wall/same height about 3 feet away in the garage.

This is the jut-out in the garage where the bathroom is. The PVC pipe is from the upstairs shower, which runs in the ceiling for the downstairs bathroom. The 4" metal duct would come out 3ft to the left of that black PVC pipe (the plaster deck you see there is roughly the same height as the bathroom ceiling)

 
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Old 04-13-12, 12:54 PM
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Is it safe to drill a 4" hole for a vent in the 2x10 between the 1st and 2nd story?

(the 2x10 that the end of the joists connect to, between the garage wall and bathroom)
 
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Old 04-13-12, 01:12 PM
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My recollection is you can't cut a hole which has a diameter greater than 1/3 of the height of the joist.
 
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Old 04-13-12, 01:26 PM
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I believe it's the rim joist (highlighted in green)


We have a garage ~75% the height of our 2-story home, so I'd pop out through the rim joist between the 1st and 2nd floor, into the garage, then 90 it out to the soffit (~6-8ft of 4" duct total).

The part of the rim joist I'd be drilling through is right above the edge of a closet door, but it's essentially an outside wall (that goes to the garage). There is a small jut-out in the garage where this closet is (see picture in previous post, where PVC drain pipe comes out in the same joist).

On a side note, I'd need to cut out a foot of 1x3" strapping in the ceiling to make the fan/vent fit, shouldn't be an issue as it's just holding up the sheetrock?
 

Last edited by skibum01; 04-13-12 at 02:01 PM.
 

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