question about sink drain size

..........

Since it's already there ... just put a 1 1/2 x 2" bushing in the fitting and run out a 1 1/2" pipe with a trap adapter. If you use a female trap adapter it will slide over the end of the 1 1/2" pipe and does not have a stop inside so you can have plenty of room for adjustment to place the trap very easily.

You can put a 2X1-1/2 bushing into the tee (its not a wye) for your lav. The barsink you can reduce down with a reducing coupling at any point. The problem I see however is that your vent doesnt appear to be high enough. It should be at least 6" above the flood level rim of the lavatory. Also, do you have spec sheets for the lavatory? Perhaps its the angle that the picture was taken from, but the drain appears high too.

vents

All your vents are too low from an inspector's viewpoint, and some would have a problem with you using pressure elbows and tees instead of drainage ones, although yours technically would work. You should also have put a filler around the toilet pipe so the concrete was not tight to the pipe. You are going to have a problem when you install the flange.

ga1990,

For what it’s worth, I’ve found that the most important part of a plumbing post is to tell prospective respondents where you are. Then, look at the respondent’s location (if given). There are a lot of Plumbing Codes out there, plus each municipality might have its own variant of the regional Code. Advice given, even with the best of intentions, could be either valid, unnecessary, or prohibited in your jurisdiction. Further, different Codes use different terminology. For example, a Trap Arm is defined in the UPC and the NPC, but is neither defined nor referenced in the OBC. Likewise, Branch is defined in plumbing glossaries as "Any part of a drain system other than the main, riser, or stack," while the NPC and OBC define it as:

"a soil-or-waste pipe connected at its upstream end to the junction of 2 or more soil-or-waste pipes or to a soil-or-waste stack, and connected at its downstream end to another branch, a sump, a soil-or-waste stack or a building drain."

Though most “expert” posters are aware of the existence of such differences... if not the differences themselves, if the reply is from a poster locked away in his own little world, he might resort to hostility, ridicule or patronizing comments if you don’t use trade practices or terms he is familiar with. At the very least, his advice might not be applicable to your case.

Even if your installation is not subject to inspection, you would probably want to make sure it works. While most Codes try to ensure proper functioning of an installation, oftentimes, they set only minimum standards. But that might not be enough to meet your needs or wants.

So, before you undo any more of your neat work, make sure the advice you follow is from a reliable source.

For your entertainment, consider the following:

The hog farmer tells his neighbor that his hog is sick. So the neighbor says:

“Give them plenty of water.”

Next day, the farmer says:

"I gave them lots of water, but she died anyway. To make matters worse, now another of my hogs is sick."

So the neighbor suggests:

“Disinfect the sty with bleach.”

Next day, the farmer laments:

“I used up all the bleach in the house, but my second hog is dead too. Now my third hog is sick, as well.”

[And it goes on till all the hogs are dead]

When the last hog dies, the farmer tells his neighbor that he’s ruined because all his hogs are dead.

So the neighbor says:

“They’re all dead? That’s really too bad, ‘cause I still have lots of good advice.”

Cheers