Bathroom layout help

[mccombbj]

Hello, I have an old building that I plan on adding a bathroom (with toilet + sink), and then an external sink next to the bathroom. I have come up with the following design and hope everyone can tell me what I could do better. Disregard the red as I couldn't get it to line up in the program. Also I don't have access to the stack so I will be installing an AAV on the top most pipe. The bottom exposed 4" pipe to the left will be a cleanout. So does this look appropriate for how it should be designed or how could it be better?

 

[mccombbj]

side view

 

[MicEd69]

Here's a few comments on your sketch.


The toilet vent is not needed as it will be wet vented through the sink drains. I assume the two "open" lines to the right are the two sinks. There are limits on how far the P-traps can be from the vents. Line sizes are needed to confirm those limits. And AAVs are not allowed everywhere. It would be better to run the vent up through the roof. All vents do not need to be connected to the stack. The wye I questioned needs to be a Sanitary tee if there is not a separate vent in that drain line that I'm assuming is from a sink.

 

[mccombbj]

Thank you Mike for your helpful response! Ok, I'll change both lines to be at a 45, I had the toilet vent because the distance from the toilet to the sink drains will be more then 6 feet, this requires a vent right?
The bottom one is a 2" long radius Tee-Wye hub, How does the following look?

 

[MicEd69]

Thank you Mike for your helpful response! Ok, I'll change both lines to be at a 45, I had the toilet vent because the distance from the toilet to the sink drains will be more then 6 feet, this requires a vent right?
The bottom one is a 2" long radius Tee-Wye hub, How does the following look? View attachment 45692

Yep. better. Apparently, you are under UPC or a derivative thereof. If you are under IPC, you don't have that 6' restriction for a toilet vent. So as long as the vents for the P-traps are within the maximum distance required because the size of the drain lines for the sinks, you should be fine.

But I did forget to mention that the vent connection to horizontal drain line for the nearest sink probably needs to be a combo or a wye with 1/8th bend. Some interpret that it can be a Sanitary tee on its back, but others say it has to be a combo fitting. I would also suggest adding a cleanout in both vertical vent lines of the sinks.

 

[mccombbj]

For some reason I posted something but it never showed up so I'm posting again. So does this look better?

 

[MicEd69]

For some reason I posted something but it never showed up so I'm posting again. So does this look better?
View attachment 45722

I'm assuming that the tees you added to the red vent lines are your cleanouts and that they are accessible from above. And assuming the distances between the sink P-traps and the vent connections meet requirements, and the slopes on the drain and vent lines are proper, looks good to me.

 

[mccombbj]

Thank you for your help! It's nice to have a second set of eyes on things, especially when I don't do plumbing very often. Here is my final updated one.

Yes the red open pipes will be the cleanouts as you suggested. Basically there is this service alley way, and all this pipe will be open and it pops through a wall to provide a bathroom that has a toilet, and a sink to the right of it. This will ultimately be a tattoo shop so they need a sink next to the bathroom out in the open for the health inspector.
The front space is going to be the tattoo shop, and the back I'm going to turn it into an apartment so I also have a question about setting this back apartment up.
Basically from one drain line + one vent line I would like to make the current bathroom (which is just a sink and toilet) include a tub/shower and on the opposite wall have a sink for the kitchen. Like the following. The top line is a vent.

 

[MicEd69]

 

[mccombbj]

Thank you again, I fixed the upside down double sanitary tee, and the top one you marked is a sanitary tee, however why is the low transition from vertical to horizontal a wye with a 1/8 bend, shouldn't this be a sanitary tee as well? I'm asking because there are pictures like the following which say the transition from vertical to horizontal should not be wye's, or is there some combo reason this doesn't apply?

 

[mccombbj]

here is my latest drawing

 

[mccombbj]

Now I think it clicked, we probably don't need that if it's being vented upstream, I guess that vent sweep on the right is also going the wrong way, it should be towards the ptrap for the right sink right? Or would this just promote a clog since it's going against the drain.

 

[MicEd69]

Now I think it clicked, we probably don't need that if it's being vented upstream, I guess that vent sweep on the right is also going the wrong way, it should be towards the ptrap for the right sink right? Or would this just promote a clog since it's going against the drain.

Yes, that is correct for the wye and 1/8 bend (aka combo) for the horizontal to vertical transition for the drain line. As the horizontal drain line is vented upstream of that fitting, you can use a wye and 1/8 bend which directs flow a little better than a Sanitary tee, and that connection doesn't need any air to flow through to "protect" the P-trap from being siphoned.

But no on the direction of that upstream vent connection. As you are wanting to provide air into the line so you don't siphon the P-trap, it may seem logical to point it towards the P-trap, but that is incorrect. The cleanout you added is so that you can snake the drain line. If the wye and 1/8 bend was pointing towards the P-trap, the snake would go towards the P-trap instead of the drain line. And that is also why some don't like a Sanitary tee on its back for a vent connection. A wye and 1/8 bend will better direct the snake in the direction you want it to go.

The picture you show where the Sanitary tee on its back is prohibited is showing a vertical drainage line into a horizontal drain and not a vertical vent connection to a horizontal drainage line. Transitioning from vertical to horizontal for a flowing drain, you definitely need a wye and 1/8 bend. A Sanitary tee on its back does not direct the flow and can cause drainage problem upstream in the horizontal line. But if there is no drainage flow down the vertical line, as in a dry vent, that connection is just to allow air into the line to keep the flow from siphoning out the P-trap. As such, some plumbers and inspectors interpret the language of various codes that Sanitary tees on their backs for dry vent connection on horizontal drain lines are acceptable, but some don't.