Adding a mini bar sink to bathroom drain line

[dcourtney]

Hi All,
Im in the process of finishing my basement. Ive completed the framing and am working on plumbing and electrical plans. We decided that we'd like a 14-15" bar sink included that would sit behind the surround shower wall. My question is, can I tap into either the bathroom tub or sink waste line (and then vent under the barsink)? The plumbing under the concrete slab was roughed-in by the builder. I was able to take some picture of the neighbors bath before drywall (with their permission) so I could reference them as I build out. The only difference is the placement of the tub line. Ours is located in a cut out 10" from the wall. Ive included pictures below. My initial thought was to run a 1.5" line from the bar sink to either 2" line at the tub or bathroom sink.

Above photo is the neighbors plumbing before drywall. Our layout is the same except for placement of tub drain in concrete. To the left of the tub is where I'd like to place the barsink.

Above image is current rough-in of sink and toilet lines.

Above image is behind tub. The wall with the electrical lines is where we'd like to place the sink. Also a closer image of tub rough-in.

 

[Dj2]

Run it to the bathroom sink drain.

 

[Sponsor]

 

[dcourtney]

Run it to the bathroom sink drain.

Thanks dj2.
For a followup, I plan on boring 2" holes in the studs on that wall to run the 1.5" pipe. Im confused as to code as its not clear. On non load bearing walls, can I bore holes thru as many studs as necessary, or is it limited to 2 consecutive?
Thanks again!

 

[Dj2]

A quick visit to your local and friendly building dept will get you the correct answer.
Tell them your neighbor sent you.

Rule of thumb: holes should not exceed 40% of the width of the studs. If you have 2x4 framing, holes should be 1.4" or less, meaning: you can't bore holes to run a 1-1/2" pipe. Usually builders put 2x6 (or double 2x4) walls for this exact purpose. I know, a pain in the a.. and a waste of space. And metal protection plates must be installed.

 

[dcourtney]

This is the code that has me confused.
"Bored holes not greater than 60 percent of the width of the stud are permitted in nonbearing partitions or in any wall where each bored stud is doubled, provided not more than two such successive doubled studs are so bored."
I interpret this as bored holes up to 60% on non load bearing walls with no limit to amount of successive studs that can be bored. On load bearing, 60% if the studs are doubled and you may only bore in two successive studs in this case. Am I interpretting this correct?
I'll confirm with the locals here, just thought Id get an opinion online.
Thanks for the advice!