Bathroom exhaust fan exit

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  #1  
Old 09-17-20, 06:37 PM
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Bathroom exhaust fan exit

Is it possible or acceptable that my bathroom exhaust fan is connected to the bathroom plumbing vent stack?

was up in the attic to examine the master baths exhaust fan. Thinking of replacing it. Itís an older unit with a 3 inch exhaust, vented to the ridge vent.

the second bath appears to be vented to the plumbing vent. It looks like a large (2.5-3Ē abs pipeĒ). I didnt examine it closely as I was up there without a mask and thereís a lot of blown in insulation.

so...

1. I want to replace both fans. Is a ridge venting acceptable? How about gable venting? I have a gable vent near by.

2. is venting through the plumbing vent acceptable?

if I need to cut the roof open for new vents, I will wait til the shingles need to be redone. Also found a bat in the gable vent between the Lou era and an interior screen. Think I will screen the exterior too as there is guano building up between the screen and Louvers
 
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Old 09-18-20, 01:32 AM
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Old 09-18-20, 05:06 AM
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1. A bathroom vent must have it's own connection outside. You can not simply run a pipe or hose up near the ridge or gable vent.

2. No, a vent fan can not be connected to the plumbing vent.
 
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Old 09-18-20, 07:51 AM
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Can two exhaust fans exit through one roof vent?
 
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Old 09-18-20, 04:48 PM
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Can two exhaust fans exit through one roof vent?
No.... they cannot. .........................................................
 
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Old 09-18-20, 06:40 PM
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Two vent fans can only be connected if they have an inline booster fan to increase airflow. Also known as a remote fan. The individual bathrooms do not need their own fans if you have a remote fan. They are also quiet... often almost imperceptible.
 
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Old 09-19-20, 12:03 PM
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Best move would be to have two roof jacks installed when the roof is re-shingled. It shouldn't be expensive, and it is the correct way to vent those fans.
Andy
 
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Old 09-20-20, 03:17 PM
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Anyone want to guess what that silver box is next to my fan and exhaust pipe? My teenage son went up to take some pics.







 
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Old 09-20-20, 03:21 PM
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I’ve also confirmed the 2nd fan does not hook up to the plumbing vent. My couldn’t find the end if it, but I suspect it’s vented at the soffit......without a proper termination cap. The main is just run up to the ridge, so I suspect the 2nd is just run to the soffit.

the main will be easy to replace. The 2nd fan is very close to the edge of the soffit, it’s a tight fit in that area, with my son complaining even he is sore.

sigh.....
 
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Old 09-20-20, 04:04 PM
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That looks like a piece of 4"x10" metal duct.
 
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Old 09-20-20, 04:18 PM
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Hmmmmmmmmmmm..............
 
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Old 09-20-20, 10:38 PM
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Are there restrictions on how close the exhaust vent can be from an existing gable vent?
 
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Old 09-24-20, 09:48 AM
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And whatís the best end cap style for use with vinyl siding in a area with bats?
 
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Old 09-24-20, 10:17 AM
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I think code is 3 feet from any potential spot that would cause recirculation. And to my knowledge there is only one style of bath/dryer vent for vinyl siding. Google vinyl siding 4" vent.
 
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Old 09-24-20, 10:35 AM
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They also make under soffit vents!
 
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Old 09-24-20, 10:35 PM
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Struggling to figure this out. Can you use or do you need to use a mounting block to screw the vent onto?
i have vertical siding and if I mount it directly to the siding, it will create a bit of a gap where the vinyl seam is.

there is another vent already in another location where no mounting block is used.

Iíve seen ones that are for new construction.....do you use the same ones for retrofitting?
 
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Old 09-25-20, 05:33 AM
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You said you have vinyl siding. Regardless of how the other one was done, the proper way to do it is to use a mount with a flange and trim ring, as I said before. If you are calling that "new construction" then yes, that is what you use. It is the only kind to use with vinyl.

https://www.homedepot.com/p/Builders...4117/100673014

https://www.homedepot.com/p/Novik-7-...0001/313135260

A third alternative would be to install a large flanged mounting block, which would give you a perfectly flat surface (with no profile like vinyl siding has) to mount a dryer vent on and then cut a 4 1/8" hole in it and use a standard type of dryer vent that screws on. You would caulk behind the vent as you mount it to the block.

https://www.homedepot.com/p/Ply-Gem-...H04H/202674751

The reason you should not just drill a hole in the siding and install just any type of vent is that the vinyl siding has a profile and the dryer vent is flat. You would need to caulk the crap out of it to seal it up which looks very bad and is amateur. It does not allow for movement of the siding either. Plus the caulk will likely fail and it will leak. A mount with a flange can be taped to the WRB and it allows for siding movement and does not need to be caulked.
 
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Old 09-25-20, 03:17 PM
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Got it. Was finally able to find these at our Home Depot (in Canada). Haven’t purchased yet....awaiting colour decision from wife.

in terms of process.....do I still go ahead and drill the 4 inch hole and then install flange with tape (or are nails needed).

or do I cut out a square in the existing vinyl?

the flange I’m looking at buying already has a 12” pipe extension on it
 

Last edited by zhy987; 09-25-20 at 04:33 PM.
  #19  
Old 09-25-20, 04:20 PM
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What is a "roof jack"? I've never heard that term, is it local?
 
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Old 09-25-20, 04:25 PM
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It doesn't matter.

The thing I would recommend is that you use a 1/4" x 12" long drill bit to drill a pilot hole through the entire wall. Mark where the center of the hole will be on the inside and then drill straight through. This will mark your hole inside and out. Then take your 4 1/8" hole saw and use that pilot hole to drill the hole inside... then go outside and drill the hole on the outside.

CWBuff, by "roof jack" he means 4" vent hood. Like the Broan 636.

Roof jack actually refers to a flashing assembly around a pipe or duct. Roof jacks are made for a wide variety of roof penetrations.
 
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Old 09-28-20, 09:32 AM
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Thank you.

whats the preferred method routing the vent pipe? Iíve got about 15-20 Foot horizontal run from the fan to the gable.
i know it should be slightly sloped. So do you just come off the fan straight up for about a foot Or two and then Across on a slope?
 
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Old 10-05-20, 03:46 PM
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So I bought the first item you described by XSleeper,

once installed, when water come down the top of the vent, I assume it runs down behind the vent opening....but then.....if face of the vent is BEHIND the siding, wonít the water then go behind the siding?
 
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Old 10-05-20, 04:01 PM
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It is expected that vinyl siding leaks. That's the way it is designed and that's why a WRB is required behind it. The WRB is the means of protecting the sheathing and framing from leaks at any penetration, such as a window or vent.

If you want to go the extra yard, you can flash the bottom of any mount (or window) with a wide piece of trim coil, (the coil is notched and goes behind the mount) so that when water gets in around the mount, it is immediately directed out over the nail fin of the siding below and to the weep holes of the siding. The top and sides of the flange can be taped to the WRB with flashing tape.
 
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Old 10-05-20, 04:03 PM
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And....so I screwed up a little. I cut the opening a bit too large. I should have bought a siding removal tool and did it properly.

so, the siding I cut away is now slightly too large. Itís on the far side of the house so nobody will ever see if....but itís not perfect.

is there a type of trim I could buy to cover my mistakes? The retailer online lists the following trim types: beltline, corner, finish, j trim, under sill
 
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Old 10-05-20, 04:20 PM
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Not really. About the only thing you could do is put a 1 1/4" j channel around all 4 sides of the mount. Caulk the perimeter where the j channel meets the mount.

Unzip the siding this time, and cut it to fit inside the new j channel.
 
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Old 10-05-20, 04:26 PM
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I enjoy doing this stuff and learning most of the time.....other times, I say.....”why didn’t I hire a pro”.
 
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