Basement bathroom -- acceptable wet vent to use wye into main sewer line?
My thought is that the Laundry line (up between the joists) might be what you really want to tap into for a wet vent in this situation, as opposed to dropping into the main line. 4DFUs of drainage in a 2&quot; pipe is what you have (washer plus laundry/utility sink, each 2 DFUs), and is the maximum amount allowed for a wet vent of that size. Buys you a few inches over the main line (and will be effectively a dry vent 99% of the time.)