Moving a shower vent to opposite wall

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atrus5

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I'd appreciate any advise on moving a bathroom vent.

After removing the old fiberglass shower unit to change to a tile shower I found that the vent pops up out of the floor before reaching the wall due an LVL beam in the way (house center beam that joists hang off). The vent took advantage of the raised floor and seat area of the fiberglass unit to do this. The photo with blue plumbing shows the current situation.

I don't think I can reroute the vent to an adjacent wall due to limitations on holes in joists so I am hoping I can vent up through the opposite wall of the shower/toilet area.

There is a walk-in clothes closet on the other side of the wall I want to run the vent through so I can cut out the floor in there to access the drain downstream if needed.

What I am considering doing is moving the toilet wye farther downstream (under closet) so I can use a 3-3-2 wye or combo to tie the vent up into the wall from the 3" drain between the shower trap arm and the toilet wye. Is the photo with red/purple markups proper?

The drain is high since it is the beginning of a long run so I'm not sure I will have the space to fit the combo beneath the wall/floor. Any thoughts on how I can fit a wye or combo in there? If it helps, can I roll it 45 degrees (assuming I can figure out a fitting to turn it back up skyward?

I appreciate any help.

(Hopefully it's going to be removed but I am also curious if the original vent was even done correctly since it appears to have a horizontal run below the floor and the wye with the shower trap arm is rolled up slightly as shown in the one photo.)


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John Gayewski

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To have a horizontal vent under the floor you'd need to drain your lav into it to from a horizontal wet vent. Both what you had before and what your proposing isn't legal. You need to have a vertical dry vent if you can't drain the lav into it. Where's the wall for the shower faucet?
 

wwhitney

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what your proposing isn't legal.
I believe the proposal is to run the shower trap arm to under the wall on the right, pull off a vertical dry vent into that wall, and then downstream of that have the WC join in, letting the dry vented shower wet vent the WC. So that's all fine, as long as the shower trap arm can reach the wall before falling more than 2", while maintaining the minimum slope of 1/4" per foot.

The IPC would actually allow the WC to join before the vent comes off, which would reduce or eliminate the need to open the floor in the closet behind that wall. It calls that "common venting at the same level." But bringing the WC in downstream still seems more typical.


As to the cleanout on the shower trap arm, it's not needed or typical. The old layout had a cleanout on that horizontal dry vent under the floor as a way to be able to address the problem such a dry vent can encounter.

Cheers, Wayne
 

atrus5

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Hi John. Thanks for the reply.

The faucets are off the photo to the lower left corner. I will have to open the floor there to move the lines into the wall since they are proud of the studs to be close to the shower fiberglass.
 

atrus5

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I believe the proposal is to run the shower trap arm to under the wall on the right, pull off a vertical dry vent into that wall, and then downstream of that have the WC join in, letting the dry vented shower wet vent the WC. So that's all fine, as long as the shower trap arm can reach the wall before falling more than 2", while maintaining the minimum slope of 1/4" per foot.

The IPC would actually allow the WC to join before the vent comes off, which would reduce or eliminate the need to open the floor in the closet behind that wall. It calls that "common venting at the same level." But bringing the WC in downstream still seems more typical.


As to the cleanout on the shower trap arm, it's not needed or typical. The old layout had a cleanout on that horizontal dry vent under the floor as a way to be able to address the problem such a dry vent can encounter.

Cheers, Wayne
Thanks for the reply Wayne. Yes, you describe my intent exactly.

I will research "common venting at the same level". I appreciate the idea. The WC wye is partially under the wall so might need to move anyway. If I don't have enough headroom to extend the WC arm into closet while maintaining slope is good to have another option.

The shower drain to vent is just over 4ft so enough room for slope there.

I am concerned about the space from drain to subfloor supporting a combo though. Can I roll the combo 45deg if that helps fit it and I can figure out fittings to turn it back upward?

Thanks again
 

John Gayewski

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I believe the proposal is to run the shower trap arm to under the wall on the right, pull off a vertical dry vent into that wall, and then downstream of that have the WC join in, letting the dry vented shower wet vent the WC. So that's all fine, as long as the shower trap arm can reach the wall before falling more than 2", while maintaining the minimum slope of 1/4" per foot.

The IPC would actually allow the WC to join before the vent comes off, which would reduce or eliminate the need to open the floor in the closet behind that wall. It calls that "common venting at the same level." But bringing the WC in downstream still seems more typical.


As to the cleanout on the shower trap arm, it's not needed or typical. The old layout had a cleanout on that horizontal dry vent under the floor as a way to be able to address the problem such a dry vent can encounter.

Cheers, Wayne
I see that purple - ish vent now.
 

atrus5

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Yes. Sorry for my poor choice of markup method. I originally had it red but then it just blurred in with the horizontal lines in the overlap.
 

wwhitney

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I am concerned about the space from drain to subfloor supporting a combo though. Can I roll the combo 45deg if that helps fit it and I can figure out fittings to turn it back upward?
Since you are under the IPC, you have the option to use a san-tee on its back for the vent takeoff.

But the combo is better if it fits. For a non-load bearing wall (and probably for a load bearing wall), it's fine to cut out the full width of the bottom plate in the wall when between studs. So the question is whether you can get the combo in so that it doesn't interfere with the drywall on either side.

Straight up is simplest, but you certainly can roll the combo 45 degrees and use a 45 degree elbow (possibly street) to turn the vent vertical. You shouldn't roll it more that 45 degrees off vertical.

Cheers, Wayne
 

atrus5

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Since you are under the IPC, you have the option to use a san-tee on its back for the vent takeoff.

But the combo is better if it fits. For a non-load bearing wall (and probably for a load bearing wall), it's fine to cut out the full width of the bottom plate in the wall when between studs. So the question is whether you can get the combo in so that it doesn't interfere with the drywall on either side.

Straight up is simplest, but you certainly can roll the combo 45 degrees and use a 45 degree elbow (possibly street) to turn the vent vertical. You shouldn't roll it more that 45 degrees off vertical.

Cheers, Wayne

Thank you very much for all of the advise!!

I have decided to go with a Sanitary Tee but only after trying to find another option that fit and much internal mental wrangling. Your reply makes me feel MUCH better about it.

I spent yesterday in the attic playing in cellulose (Plumbers must hate that part of the job) and have the vent rerouted down the new wall. I hope to install the Sanitary Tee today to tie the vent into the drain.

If I used a combo or a wye at 45 roll and a 60deg elbow I'd still have to hollow the drywall slightly and even knowing the baseboard will "protect" it, I just don't feel comfortable with the pipe there. As important, I don't trust my ability to put the fittings exactly where they need to go to accomplish the tight fit.

I've read a bit in forums on using a Sanitary Tee on it's back and realize the concerns but I think they are the lesser concerns FOR MY SITUATION:
- "Difficulty snaking down roof stack": There are multiple wyes off the stack in question and I suspect it's difficult to control which path the snake takes in my attic anyways to route to that vent versus another. Having the shower as the only thing upstream from the toilet should help keep things clean. After 30 years of living here I've never needed to have anything cleaned out (famous last words?).
- "Potential conversion of the vent to a drain in a future renovation": This area is only 1 story with a roofline that will never support anything above it.
- "Not to code or inspectors don't like it": My understanding is that Sanitary Tees used to be allowed horizontally for most areas by code. Maybe my house is old enough that it would have had one there anyway.?. (Although you have clarified it meets code in my region currently.)

Again, my sincerest thanks!
Randy
 

atrus5

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If I can bother you one more time...

With the toilet arm extended to just the other side of the wall I'd like to confirm that 3inch pipe only requires 1/8"/ft slope - is a 1/4" better or should I shoot for 1/8"?

Bonus question: Since I have enough of both 2" and 3" pipe to extend the shower arm across the length of the floor cutout is there a preference? I likely won't keep any leftover material around for the "next job".

Here I show the 2" pipe running the 51" from shower trap to vent sani-tee in this rough mockup (lengths and slopes not correct).
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Best Regards,
Randy
 

wwhitney

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With the toilet arm extended to just the other side of the wall I'd like to confirm that 3inch pipe only requires 1/8"/ft slope - is a 1/4" better or should I shoot for 1/8"?
I think 1/8" may be allowed under the IPC, but 1/4" is better and I would go for that.

The shower trap arm should be 2", it can go to a 2x2x1-1/2" combo or san-tee on its back, and then into a 3x2x3 or 3x3x2 wye to pick up the WC, depending on where you want the combined line to be in the joist bay. [3x2x3 wye is made with a 3" wye and a 3x2 bushing.]

Cheers, Wayne
 
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