plumbing questions

[scattermaster]

So,
My garage is an empty shell on a slab. No plumbing in the slab.
I intend to install a bathroom with a toilet and a sink.
I ordered a back outlet model so I can simply go straight back through the wall and then down into the sewer pipe.
My question is how to get my sink drain there as well.
My 1st thought was to have the toilet at the end of the sewer pipe and run the sink into the vent pipe like in my picture.
Since it's a 4" vent it seems like the toilet would not pull a suction on the sink P trap. Also, the sink drain shouldn't affect the toilet?
Is that kosher?
My second idea is to have the sink at the end of the sewer pipe and run the toilet down stream of the sink drain.
What do you think?
Jim

 

[paredown]

Typically, 'wet' venting is allowed with a sink, so the discharge after the p-trap can go straight into the vent pipe above the level of the toilet. There will be no problem with suction, since the vent is clear above the sink. Sink needs to be the highest point.

I ca't tell what you have mocked up, but use a single line for toilet trap to waste, vertical for full sized vent, and then tap into that vertical vent at the appropriate height to attach the sink drain.

There may be distance constraints--I can't remember them, but you are clustering close together so not a problem.

 

[K'ledgeBldr]

As paredown lamented to- have the discharge go directly into the vertical wet vent (sanitary ell). Have the drain from the sink above the discharge of the toilet.

If the sink is going to be the standard distance from the toilet (toilet requiring 30”- 15” from center)- the sink would probably require a revent pipe (auxiliary vent), but you could use an AAV instead. Especially since this- I assume- will be a seldom used sink.

 

[scattermaster]

thx guys.
The toilet is right at the wall inside the building. It's outlet is centered at 6 1/2" above the floor. You can see where it comes to the santee in my 2nd pic. (comes out of the wall) and then straight down into the 90 which is the end of the sewer pipe. (when I find out how low the sewer pipe will be, I will extend it so it lines up)
Not sure how high the sink is, but the P trap under is it 15" higher than the toilet outlet. Sooo, it's 15" higher?
Sounds like my 1st pic will bo OK then?
thx,
Jim
EDIT- I guess i need to add an auxiliary vent for the sink and bring it up over the top of everything else and then into the vent.

 

[Bert_]

Use a tee instead of a wye+45 going to the sink. Also upsize to 2" and it will vent fine over that short distance. It's called a wet vent.

 

[59 wagon man]

way too complicated on the line going to the toilet all you needed was a 4 x 2 y to tie the basin in

 

[scattermaster]

59 wagon man,
The more complicated pic was my backup idea if I couldn't use the idea in my 1st pic.
My 1st pic only has one stack and uses a tee to tie in my sink.
The only thing is I used 1.5" pipe instead of 2".
Would that still be OK ?

 

[Bert_]

59 wagon man,
The more complicated pic was my backup idea if I couldn't use the idea in my 1st pic.
My 1st pic only has one stack and uses a tee to tie in my sink.
The only thing is I used 1.5" pipe instead of 2".
Would that still be OK ?

Picture shows a wye +45 for the sink not a tee. A tee works for a wet vent, a wye does not.

I like 2 45's instead of a 90* where it changes to horizontal underground.

 

[scattermaster]

Oops!
OK, I see now. Not sure I understand why a tee is better than a wye but I'll go with the advice. I'll put a tee there and go with that model.
Thanks again guys.

 

[Bert_]

Oops!
OK, I see now. Not sure I understand why a tee is better than a wye but I'll go with the advice. I'll put a tee there and go with that model.
Thanks again guys.

If your pipe turns down without a vent it's an S-trap. With 2" a sink probably wouldn't siphon but still. A tee lets it pull air even if there's some water in the pipe.

 

[scattermaster]

I thought I'd post a pics of the finished drain/stack.
Now I'm waiting on the plumber to come out and run the line across my yard.