I have a negative pitch in the drain pipe coming out of my sink drain that attaches directly to the vent stack.
The vent stack is mostly inaccessible at the height of the p-trap though inside the sink cabinet.
My thought is that I can cap off the pipe near the vent, and run a new drain line next to the p-trap, add a Studor AAV, and run the new drain line down through the floor into the crawlspace which will be reattached either the horizontal or vertical section of the vent stack pipe.
Am I overcomplicating things, or is this the best plan for solving the issue that my drain pipe has a negative slope? If so, can I attach to either the horizontal OR the vertical part of the vent pipe?
Couple notes: The disposal and/or the p-trap can't be raised up any higher. Also, the vent pipe feels immobile (I suppose it's affixed at the boot at the roof line).