I need to establish a new drain and vent for relocated kitchen sinks, deciphering the plumbing code and existing cast iron left me with questions below (also see a proposed design attached).

  1. The first-floor vent can only attach above the flood line of the second floor sink (as shown in the diagram)?
  2. Are there any rules governing how close the first-floor vent connection is to the sink? I.e. can I just install it adjacent to the stack? (Seems to have been so in the original design but with shorter drain arm.)
  3. When the first-floor vent re-connects to the stack, am I just using a wye fitting there?
  4. The second-floor sink vents via the stack itself, and no special venting is required, correct?

I've parsed the requirements for DFUs and believe 2" will be adequate for the drain, also a prior question established the rise/run and width of drain arm, thanks.

Vent design for stacked sinks

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