I'm a plumbing newbie and I'm adding a bathtub where one didn't exist before and I want to make sure that I am plumbing the drain properly.
I have a 2" drain available to me directly below the tub and a 2" vent available on the back wall behind where the faucet will be.
Is it okay for the tub drain and trap to be 1-1/2" and then go into a 2" vent/drain?
I've attached a picture of my mockup.
Further down the line I'm fairly certain the 2" line goes into a 3" toilet which is separately vented. It's under concrete but the 2" line goes in that direction.