Under slab new plumbing help - venting/santee

[wallbobby]

I am redoing a basement (on slab) bath. I need to tie into the main 4" CIP which is under the slab, and am trying to plan things out, and I am unsure if this initial plan I have is ok in terms of venting/tee and would appreciate any help.

Red lines are the new lines I will add, and I would really like to have the vent line go up either inside one of the depicted walls, or anywhere around the HWH.

Is it ok to run one vent, right where the shower tees into the new 3" toilet line, using something like this with the side outlet being the vent,
https://www.supplyhouse.com/Spears-P416-337-3-PVC-DWV-Sanitary-Tee-w-1-1-2-Left-Side-Inlet

Thanks -

 

[wallbobby]

I guess what I'm asking is if the vent can be a singular vent at the santee where the new shower/toilet lines meet, or if it must be two separate vents, one on the 3" line before the shower line joins it, and one on the shower trap arm before it joins the 3". Or if there is some arrangement that would be better.

 

[Sponsor]

 

[MKS]

I can not say if the fitting you linked to is appropriate. It includes Santee, which are not typically used on their back.
Since this is under a slab, horizontal wet venting maybe the solution.
They start with a 2 inch vent through the roof. The first connection is typically a lav with a Santee. Then continues down turns horizontal with long sweep and picks up a shower or tub then connects to a three inch drain that the toilet is connected to.
UPC
Helpful hints.
https://terrylove.com/forums/index....-hints-by-bert-polk-plumbing-inspector.37064/

 

[wallbobby]

So if I ran a vent somewhere between the toilet and the spot that I've put in a santee, would the shower be effectively wet venting if it connected with a simple wye? I did the santee just to make it a single fitting - obviously there could be a separate vent earlier. I think what I'm asking is if the 3 inch toilet line can be vented, and that effectively vents the shower trap arm as well.

 

[MKS]

"I think what I'm asking is if the 3 inch toilet line can be vented, and that effectively vents the shower trap armaswell."
Not to my understanding.
The shower trap arm needs to be vented within,, I believe 5-6 feet of its trap prior to entering the three inch line the toilet empties into. I believe I have read that this could wet vent the toilet then. Toilets require a 2" vent from what I have read.
Needs to be confirmed.
The vent in the shower trap arm prevents the toilet from siphoning the shower trap.
I have read here that if a dry vent is planned for a shower they, those who know better, prefer to have a wall next to it to run the trap arm under to connect to the dry vent in said wall properly.
Hopefully you will receive some more input.

 

[wallbobby]

I think I need to cut into the slab and discover exactly how much vertical space I have. I think it might work to have the shower connect at the top of the 3" line as it goes across, and run a vent straight up from that - wet venting the toilet, but it would only be about 1 inch of wet vent (the tee itself). These distances are all fairly small - the shower trap arm is 2 feet at most, the entire toilet run is less than 5 feet to the main sewer line.

 

[MKS]

Try to have a good plan/layout before cutting to limit the mess.
Is that lav already there? If it is vented with two inch it maybe the place to start.

 

[wallbobby]

Yes it's there, and it's vented, but the horizontal run to get to it would be below a fixture that is also served by the vent on the floor above, and anyway, I'm perfectly willing to poke a new vent out of the roof over by the toilet/shower. This is a fairly complicated situation despite the simplicity of the drawing - this bathroom is on a septic tank and I am converting it over to an existing sewer line (the house has both sewer and septic - half the upstairs fixtures were going to septic, too, in fact I just finished tying them into the sewer today, so all that's left is the toilet and the lav, and then the new shower). There are lots of plans laid out, I'm just wondering about this specific point, as in where I am allowed to vent this new toilet/shower line in the simplest way possible.