Add new sink

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by LYoung, Jul 7, 2014.

  1. LYoung

    LYoung New Member

    Messages:
    5
    I'd like to add a new sink on the left side of a 60" vanity. The new drain should be to the left of the center pipe
    Due to the placement of the vents, the current drain can't be used in the wall. Is it possible to tie into the central pipe? It is the vent for the kitchen sink underneath it. Or is the only option to run the drain in front of the wall and lose some drawer space. Or perhaps abandon the idea of a second sink at all.
    Main vent is 2", others are 1 1/2". All appear to be copper

    Thanks in advance for your help. image.jpg
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    You would move the vent over and out of the way of the lav you intend to add.
    You would then plumb to the waste line on the right.
    You can't use the vent pipe for the kitchen below. Nope! :(
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,054
    Location:
    Cave Creek, Arizona
    You could offset the lav drain to a more central location and connect the two drains to it, or you can connect a drain to the new sink and offset the existing one slightly. Or................., There is more than one way to skin a cat or install a second sink, it just takes some ingenuity.
  4. LYoung

    LYoung New Member

    Messages:
    5
    Thanks for the advice! I hadn't considered moving the center vent.

    Will this work? Or is the vent needed directly on both drains am trying to avoid having 2 large holes in the studs as this is an exterior wall.
    Is passing the water supply lines behind the drain pipe ok?

    image.jpg
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,054
    Location:
    Cave Creek, Arizona
    That is one way to do it, maybe the hardest way. It depends on how the cabinet is made as to where you can put the drain out of the wall.
  6. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    [​IMG]

    And here is one way.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,054
    Location:
    Cave Creek, Arizona
    OR, you can just put a double fixture fitting in the existing drain line and offset over to the new left hand sink with a minor jog in the existing right hand one.
  8. LYoung

    LYoung New Member

    Messages:
    5
    Thanks for your input. It was very helpful in understanding the solution. I ended up hiring a plumber to do the work and it came out similar to Terry's picture above, with the existing center vent moved out of the way to the left.

    I am finally back to work on my project following an unrelated knee injury, and I've run into another problem on the tub plumbing. I've found similar issues in the forum, but no firm solution.

    The drain for my new tub (AS Cambridge) is 1 1/4" ABS. Of course the existing trap is not in the right location. I'd bought a new ABS P trap (solvent weld) with plans to cut the old trap off and connect the new P-trap with a 1 1/2" shielded coupling.

    The problem is that the new ABS p trap is 1 1/2" and the existing drain is 1 1/4" copper (originally, I had measured the OD - 1 1/2")). Can I use a 1 1/2" to 1 1/4" shielded coupling to connect ABS to copper? If not, what are my other options.

    I can add pictures tonight if that helps. Also, let me know if I should start a new thread, as the original title doesnt really apply anymore.

    TIA for your help!
  9. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    You're not supposed to downsize.
    You really have a 1-1/4" DWV copper waste line there?
    1-1/2" tubular will fit inside a 1-1/2" pipe. Is that what you mean?

    In old homes, they used to run the lav with 1-1/4", the tub and the shower with 1-1/2"
    Now with plastic pipe, we tend the run the lavs with 1.5" unless there are two, which then becomes 2" before they split.
    Tubs are 2" drains with 1.5" p-traps, and shower are 2" traps.

    The fitting you mention will join the pipes, it's normally done for the other flow direction.
    Snaking could be difficult.
  10. LYoung

    LYoung New Member

    Messages:
    5
    The house was built in 1968 and has all copper drains and vents except the main line in the basement which is cast iron. The tub drain measures 1 1/2" OD. I have not cut the pipe to measure the inside but assumed at was 1 1/4". Bad assumption?? The 1 1/2" shielded coupling I bought fit the abs pipe, but not the copper pipe.

    Does this really need to be cut all the way back to the main drain and tied in there? It is a 2"OD copper pipe that is at the left of the picture above. Or should the vent pipe bereplaced with PVC up through the roof?

    What seemed so easy has become so complicated.
  11. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    I'm guessing you have a 1.5 copper DWV drain. They were never run in 1.25"
    The OD would be 1-5/8"
    Just pick up a copper by plastic coupling and try it.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,054
    Location:
    Cave Creek, Arizona
    1 1/4" copper would be 1 3/8" o.d., and would only have been installed by a VERY incompetent 'plumber".
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,054
    Location:
    Cave Creek, Arizona
    When you are measuring o.d., are you measuring the tub's waste and overflow fitting? That WOULD be 1 1/2" o.d. in order to fit IN TO a 1 1/2" waste pipe.
  14. LYoung

    LYoung New Member

    Messages:
    5
    I finally cut the copper pipe. It was indeed 1 1/2" ID . I attached the ABS with a 1 1/2" shielded coupling. I'll dry fit the tub before I glue the trap together to make sure everything is in the right place.

    Thanks for everyone's help on this! This forum is invaluable.

    Now on to the next project. Hopefully the last for now.

    The toilet drain is 3" copper. Of course the flange is too high now that I took out the old mud pack floor. I had gotten a push in type flange with a gasket on the bottom. I've read this is not ideal and can clog.

    I can't find the kind that goes around the outside of the pipe. I don't think I'm searching for the right thing . Can you supply a model number or name of what I'm looking for? Or s it preferable to just cut the copper and attach a length of PVC with another coupling and glue in a flange?

    TIA
Similar Threads: sink
Forum Title Date
Plumbing Forum, Professional & DIY Advice Adding washer drain and sink to garage- pics Nov 19, 2014
Plumbing Forum, Professional & DIY Advice Removing the water supply line on a kitchen sink Nov 16, 2014
Plumbing Forum, Professional & DIY Advice Adding garage utility sink - use existing 1st floor bathroom drain and vent? Nov 13, 2014
Plumbing Forum, Professional & DIY Advice Sink Defect (Kohler Pennington) - I Should Have Checked It First Nov 12, 2014
Plumbing Forum, Professional & DIY Advice Bathroom sink woes Nov 10, 2014

Share This Page