I have home that is 8yrs old. The basement was roughed in for a toilet only and now I would like to add the shower and sink before closing everything off. The problem is the rough in for the sink and shower do not exist. The toilet is currently about 8' from the main soil stack that comes from the first story.. I believe this is probably a “wet vent”?

If I were to add a shower and sink I will need to tap into the sewer line. To do this I am looking to know if I should use a 2” drain for shower and sink. Or does the shower require 3”? The next question is how to vent everything. I am hoping I can use the same method used for the toilet for the shower. As for the sink, I am thinking this will need to be a studor vent as I do not have an option to vent through the roof. Any suggestions? I have include a rough sketch.

As for busting up the floor, do you have any suggestions for how much room is required to work in this area? How much floor do I need to remove?

The main soil stack is just that and no way is it a wet vent. You may not connect anything to it that isn't vented or wet vented. I gave you a rough drawing of the way you will be connecting the lavatory and shower. You will be already connected to the sewer by the 4" toilet drain line. this is the line you'll be connecting the shower and lav into. You will vent the lav with a AAV coming off a tee just downstream from the trap. The shower will connect to the 2" lav drain and be wet vented by the lavs AAV. Since I can't be there to lay the job out in detail you'regoing to have to make your own material list. If you're going with PVC don't forget to prime before your glue. Good luck, Tom

Thanks for the quick reply. That's awesome. As for the AAV I should still be able to fit this under the sink right? The tee you mentioned just downstream from the trap, does it come of the 2" from under the ground?

The last question is when I take out the concrete, do you have an idea for how wide to make my cuts to get enough room to work with the pipe?

I was thinking of renting a electric or gas power concrete saw with proper ventilation of course. Plus an electric jack hammer..

"The tee you mentioned just downstream from the trap, does it come of the 2" from under the ground?"

The lavatory will be picked up by a 2" pipe that raises up behind the cabinet 18" to the center of a 2 X 2X 1 1/2" drainage tee. The 1 1/2" stubout from the tee will pick up the trap and the AAV will mount on top of the tee.

"The last question is when I take out the concrete, do you have an idea for how wide to make my cuts to get enough room to work with the pipe?"

You will have to lay your fittings out on the floor first. Then mark out 6" either side of the center of the pipes for a 12" trench. Remember that old plumbers saying. " Measure twice and cut once."
Good luck, Tom

What is the pitch of the 2" drain? 1/8" per foot or 1/4" per foot?

As for connecting to the 4" toilet drain, would you recommend the compression fittings or take out the entire 4"PVC back to the toilet and glue all new pieces?

"What is the the pitch of the 2" drain? 1/8" per foot or 1/4" per foot?"
!/4" to the foot but if elevations tight then 1/8th is acceptable . Whe4n we run drainage we make our slope to just crack the bubble on our levels.

" As for connecting to the 4" toilet drain, would you recommend the compression fittings or take out the entire 4"PVC back to the toilet and glue all new pieces?"

You should already be roughed in from the toilet to the sewer main. You're going to have to branch off from the 4" toilet line using a 4 X 2 wye or combination wye and eighth bend,( combo) to pick up the lavand shower.
It would be better if you could make them street fittings, ( a male end on the bottom instead of a female hub,) however, if you can't locate a street wye or combo just glue a short piece of PVC into the hub. you may now cut a piece out of the 4" that measures the same as the measure from the base of the 4 X 2 hub to the bottom of the male end plus 5/8ths of a inch. After you set the pitch on the 2" outlet the hub will prime and glue in to the 4" and the male end will connect with a 4" No-Hub Band, (see attachment.)
Figure out what slope you'll be using by measuring out the longest 2" run and multiplying by 1/4 or 1/8. That will give the total amount of fall for that run. Good luck, Tom