I'm reading the Indiana plumbing code, and section P3107.3 says:
P3107.3 Connection at Different Levels
Where the fixture drains connect at different levels, the vent shall connect as a vertical extension of the vertical drain. The vertical drain pipe connecting the two fixture drains shall be considered to be the vent for the lower fixture drain, and shall be sized in accordance with Table P3107.3. The upper fixture shall not be a water closet.
Italics theirs, Bold mine
When they say "connect at different levels", does that mean on different floors of the building, or at different heights on the same floor?
In particular, I've got two new bathrooms, one stacked above the other. The sinks are one one wall (above each other), and the tub/showers are stacked on the other side (~7 feet away). Is this referring to combining the vents for the two sinks on the two different floors, or is this referring to combining the vents for the sink and tub on a single floor?
My intent at this point is to have individual vents for the sink and tub on each floor, combining in the ceiling, then going up through a common vent exit for each bathroom. (I'd love to combine all venting for both bathrooms into one roof penetration, but that's a different question.)
This is the general plan, looking from the side, of a single floor's bathroom. Does this "connect at different levels" apply at the vent junction labeled
<-- Apply here?
| vent to outside ┌--------------- vent across ceiling (with slope) ----┤ <-- Apply here? | | | | | | ├--- sink drain | | shower drain | | | └--------------┤ └-------- sink drain (with slope)---------------------┴-┐ drain to basement
Assume traps exist at the drains. Work with me here...