Toilets, Sinks, Showers, Tubs and Disposals - Bathroom Sink Vent/Drain Location?

I'm trying to finish-up a variety of projects that are in various states of completion, so that I can put this fixer-upper which I've been working on for years onto the market.

This morning's quandry is where I'm converting an old mother-in-law apartment into two bedrooms and a 3/4 bath, then reopen it to the house. I realize that I'll need permits, inspections and I'll talk to the (part-time) fellow in the building department, but I prefer trying to run some of my code (and functionality) questions through here first, so that I sound like less of an idiot in town hall.


With that said, I'm having to cut a hallway into what was the apartment bath (which would reconnect it to the house). To meet the 15" distance required between the toilet and everything else, it'd only work, if I move the sink/vanity to another wall.

Everything in this part of the house is on slab, so I'm assuming that it'd be okay, if I ran the sink drain around the perimeter, back to the main drain line, where it currently drains. Hopefully somebody will tell me if I'm wrong, but basically, the drain line would be enclosed in a wall, run through a closet and then through another wall, where it'd tie back into the place where it currently drains. (I still haven't opened the walls, but the shower and toilet goes out through the slab and I assume the sink ties into one of them, somehow)

And, not only do I have this drain question, but the sink would then be more than six feet (through the walls) to the current vent (and the through-slab drain), so would I need to run an 1 1/2" vent for the sink?


Thanks in Advance;
I appreciate all of the help.

ok first off running the drain that far would most likely make it to high to connect the sink since you need 1/4" of fall (pitch) per foot so 16' would raise the outlet for the sink 4''. and yes you would need to run a vent unlesss your area allows aav's (air admittance valves)

I believe Dan is correct about the pitch for the drain, You will need to make sure you have a 1/4" per foot pitch from the vertical pipe to the vertical pipe. But dont forget there will be 2 90's and a ty involved in the math here. I think you may be ok, but it will be close. As far as the vent is concerned, an Air Admittance Valve may be possible if allowed by your local official. A standard vent would be the best way to vent it. There should have been an old vent you could tie back into once you get above the flood level rim of the sink.