Question on Basement bathroom sink waste vent rough in

[GooseBruce]

Hello all, I have a question on my basement bathroom rough in. The pipe on the right is 2” and says future lavatory on it. The pipe on the left is 1 1/2” and goes up into the next floor (single story home), vent I anssume, and there is not water above this area I am talking about. My question is does the sink drain just get tied into the pipe on the right or does I have to tie the pipe on the right into the pipe on the left and then hook my sink drain to that? Sorry if this is poorly worded or confusing. Thank you very much in advance for any help!

 

[MicEd69]

Seems that there was poor coordination between the plumber, carpenter and concrete guy. And sometimes when we ass-u-me, we make and ASS out of U and ME.
From your description, I would assume the 1 1/2" line is a vent, for the main or a branch line under the floor slab. The sink will need to be vented, and it is a little surprising that the plumber didn't include a vent connection in the vent line pointed towards the 2" drain at least 6" above the flood level of the future sink. So, you will need to run a vent line through the stud to the left of the 2" and cut a Sanitary tee into the 1 1/2" vent line. You can use 1 1/4" for that vent. You should use stud guards over the stud hole like is shown for the penetration of the vent line at the top plate. There is already drywall on the other side of the wall, so you will have to cut out the drywall to install one there or do without it on that side. If this is getting inspected, the inspector could require that. If not, just don't put that penetration around picture hanging height. Something like this:

 

[GooseBruce]

Seems that there was poor coordination between the plumber, carpenter and concrete guy. And sometimes when we ass-u-me, we make and ASS out of U and ME.
From your description, I would assume the 1 1/2" line is a vent, for the main or a branch line under the floor slab. The sink will need to be vented, and it is a little surprising that the plumber didn't include a vent connection in the vent line pointed towards the 2" drain at least 6" above the flood level of the future sink. So, you will need to run a vent line through the stud to the left of the 2" and cut a Sanitary tee into the 1 1/2" vent line. You can use 1 1/4" for that vent. You should use stud guards over the stud hole like is shown for the penetration of the vent line at the top plate. There is already drywall on the other side of the wall, so you will have to cut out the drywall to install one there or do without it on that side. If this is getting inspected, the inspector could require that. If not, just don't put that penetration around picture hanging height. Something like this:
View attachment 48114

Sir, I thank you very much for your response. You have no idea how much your explanation and image makes sense to me now. And, your ASSUME analogy is spot on, if you only knew the general and the subs he used I don’t think they coordinated much with each other at all. Thank you again