I am adding a first floor half bath to 3 units in my triplex. I want to be sure I am UPC compliant with this plan.
1A is my preferred option, but 1B is an alternative, depending upon the easiest route to get the vent to the attic.
The main question is about the fittings to use (red circles). I want to be sure I need to use Ys and 45s (or combos) rather than sanitary Ts in each case, and in case 1B, if the LAV to drain connection should be horizontal or turned up 45 degrees.
The 3” main drain is a new drain that will only service the 3 half baths, as the existing drain is only 3”. I will tie the two 3” drains into a 4” Y before going into the 4” sewer line. The WC is less than 4 ft from the LAV and less than 6 ft from the main drain.