I'm planning a basement bathroom where the plumbing was stubbed in during construction. The plumber installed a 2" pipe for a sink, 2" w/trap for a shower and 4" for a toilet. I would like to move the sink from the original location. I chiseled up the concrete and capped the sink line that was already stubbed in. I would like to move the sink to the other side of the room and tap directly into the main 4" stack.
Please see the attached picture which shows the old and new sink location. There are no vents installed yet. I'm guessing the plumber planned to vent the sink which I think would vent all three fixtures. Can I move the sink to the new location and vent it with an air admittance valve under the vanity? Would this take care of the venting requirements for all three fixtures? Is there any particular importance to sink (and vent) being upstream from the other fixtures in the original plan and downstream in the revised layout? It was probably at the end of the same line as the shower and toilet before and now I would tap directly into the main stack.
I am not a big fan of mechanical vents.
The 2" vent that seems to be what you have going on there will be ok for what you have. Your vent placement should be ok. Is there a vent you can tie into from the old sink or another place? If so I would use it. I'm from Mass so my code might be different from the code you have.
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