So I was measuring the rough-in drain locations that were installed in my basement for a future bathroom addition.

I have heard of frequent mistakes and irregularities, but I think I am basically ok...

The tub/shower drain seems fine, although it is about 24" from the block wall on the shorter dimension. I assume I'll have to frame the stud wall out from the block several inches.

Toilet drain looks ok.

Sink drain drain seems close to the toilet drain, it's about 12" away.

So here is my question: What is the maximum distance from the sink drain to the location of the sink, or sinks (in case I do a double sink or another sink in the living area)?

 

Not sure how you plan to do this but your stud wall needs to be built with the rough in drain pipe inside the wall. While doing that add a "Y" or "T" connection and cap it off for later use for 2nd sink drain.

Have your tub/shower on hand and place it over drain to take measurements for walls.

 

Yeah, I know all of that. I plan on doing the framing, but not the plumbing (not my favorite thing). What I need to know (for planning purposes) is what's the maximum horizontal distance from the current rough-in drain location to a future sink. I suppose I could more specifically ask what is the minimum stickup for the pipe coming out of the concrete (I assume just long enough for a connection) plus the minimum slope for the drain pipe heading toward the sink. But I thought someone would know an estimate off the top of their head.

 

If you tie in your vent along with your drain at the base of the new fixture - and have a 1/4inch drop/ft along the horizontal run (of the drain) - you can go about as far as you want.

 

Thanks, that's what I needed to know.

 

Re: "If you tie in your vent along with your drain at the base of the new fixture - and have a 1/4inch drop/ft along the horizontal run (of the drain) - you can go about as far as you want."

Doesn't that depend on the code one is under? At long lengths the description above is a wet vent, not allowed by my AHJ. My distance allowance is 6' max. for a 1 1/2" pipe, or 8' for a 2" pipe (both at a 1/4" per foot drop).