Bathroom venting, toilet on top

[AverageIdiot]

Hi all,

Working on some bathroom remodel and was wondering what you thought of the existing plumbing. I'm mostly concerned with determining if I should add a vent for the shower.
Currently the toilet is directly on top of the main soil stack. Next is a 3" vent pipe off a tee to the roof. Then it's the lav which has its own vent up the wall to tie in to the main vent above. Below that is where the shower drain tees in. There is about 8 feet from the shower trap to the stack.
It would be a real PIA to get a vent pipe up the wall behind the shower but would like some thoughts on how this is all stacked and whether or not a vent should be added.
Thanks in advance!

 

[Terry]

The toilet can't be on top.

 

[Sponsor]

 

[wwhitney]

On a vertical wet vent, the WC has to be on the bottom. So the stack below the WC can't be a wet vent for anything below it.

The lav is separately vented, which is fine, but the shower doesn't have a permissible vent. You could pull a dry vent off the shower trap arm. Or if you can bring the lav drain around the stack and connect it on the horizontal to the shower trap arm before the stack, then the lav could horizontally wet vent the shower.

Cheers, Wayne

 

[AverageIdiot]

Gotcha. That's what I was thinking. Thanks for confirming.

 

[Reach4]

If the yellow two vents went to lav and shower, and then those drained into a 3x3x2x2 double fixture fitting or double wye, I think the toilet would be wet vented with no added vent needed.

If the vented lav and shower each drained into a separate wye below the toilet, I think the toilet would be wet vented with no added vent needed.

If you could join the vented lav 2 inch drain with the shower drainage with a horizontal 3x2x2 wye, and then the toilet joined with a 3x3x3 wye or santee below, the lav vent should be sufficient.

 

[AverageIdiot]

If the yellow two vents went to lav and shower, and then those drained into a 3x3x2x2 double fixture fitting or double wye, I think the toilet would be wet vented with no added vent needed.

If the vented lav and shower each drained into a separate wye below the toilet, I think the toilet would be wet vented with no added vent needed.

If you could join the vented lav 2 inch drain with the shower drainage with a horizontal 3x2x2 wye, and then the toilet joined with a 3x3x3 wye or santee below, the lav vent should be sufficient.

Thanks. So if I disconnect the vent below the toilet and move it over to the shower trap arm, say about half way between the shower and toilet, that would be sufficient? Maybe 2 feet from toilet and 3 feet from shower trap or so?

 

[Reach4]

Thanks. So if I disconnect the vent below the toilet and move it over to the shower trap arm, say about half way between the shower and toilet, that would be sufficient? Maybe 2 feet from toilet and 3 feet from shower trap or so?

If you are under IPC, that vent would have to be vertical (within 45 degrees of plumb). So run the trap over to the wall, hit the vent, and then go to where you need to go.

If that is not convenient, there are the other ways.

But you still might be able to do the vent on the lavatory only.

You might even be able to use the Philadelphia single stack vent. That is on page 17 of https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf

Page 12 shows horizontal wet venting. And there are other methods too.

 

[AverageIdiot]

If you are under IPC, that vent would have to be vertical (within 45 degrees of plumb). So run the trap over to the wall, hit the vent, and then go to where you need to go.

If that is not convenient, there are the other ways.

But you still might be able to do the vent on the lavatory only.

You might even be able to use the Philadelphia single stack vent. That is on page 17 of https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf

Page 12 shows horizontal wet venting. And there are other methods too.

Good ideas. Thanks for the info.
I'll take another look tonight with this insight and see what I can come up with.

 

[Michael Young]

Hi all,

Working on some bathroom remodel and was wondering what you thought of the existing plumbing. I'm mostly concerned with determining if I should add a vent for the shower.
Currently the toilet is directly on top of the main soil stack. Next is a 3" vent pipe off a tee to the roof. Then it's the lav which has its own vent up the wall to tie in to the main vent above. Below that is where the shower drain tees in. There is about 8 feet from the shower trap to the stack.
It would be a real PIA to get a vent pipe up the wall behind the shower but would like some thoughts on how this is all stacked and whether or not a vent should be added.
Thanks in advance!

View attachment 73745

Yes, pull a separate vent for the shower.

-mike
https://homeservicestriad.com

 

[AverageIdiot]

Thinking about how to rebuild this now. The pic shows the mess I'm dealing with that I diagrammed in the first post.
Should I still let the wc drop directly to the stack, or bring the vent into a new stack and tie the toilet into that?

Note the pipes marked with X are going to be gone. The SHower line needs to be rebuilt and tied in, preferably higher.

Can I replace the two upper san-tees with a double? Or jog the vent over and bring the shower into that before going into the waste stack?

 

[Michael Young]

You'll need to add a vent for your shower and a separate air admittance valve under the upstairs lav. If you go up in the attic and see that the lavatory actually has a vent, then you don't need to add an air admittance valve to the lav.

 

[AverageIdiot]

You'll need to add a vent for your shower and a separate air admittance valve under the upstairs lav. If you go up in the attic and see that the lavatory actually has a vent, then you don't need to add an air admittance valve to the lav.

Thanks. What I was planning on now is, since the lav does has a vent, running the shower into the lav drain to wet vent it, then to the main stack.

Sort of as I tried to draw below

Note I didn't draw it but the lav has a dry vent up through the wall.

 

[Michael Young]

Thanks. What I was planning on now is, since the lav does has a vent, running the shower into the lav drain to wet vent it, then to the main stack.

Sort of as I tried to draw below

View attachment 73821 View attachment 73822

Note I didn't draw it but the lav has a dry vent up through the wall.

as long as the lavatory has its own vent, you're golden!