Back to Back sink supply line challenge

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by shelzmike, Mar 17, 2020.

  1. shelzmike

    shelzmike Member

    Joined:
    Jan 8, 2020
    Location:
    Virginia
    So I have a smaller house that has a bathroom and a kitchen that have a common shared wall and the lav and kitchen sink are literally back to back and due to size constraints, there is absolutely no way to move them away to make the drain and supply lines a little more manageable.

    As you can see in the image below, I used 2" pipe for drain. Moreover, I used the method to separate the draining and venting between the 2 sinks. I am not sure what this method is called, but I suppose the picture clearly illustrates the challenge.

    My problem is the spacing of the supply lines. 4" to the right and left of both puts the hot on the bathroom side (which is the side you are looking at in the pic) and the cold on the kitchen side directly in front of the vent pipe beside it. We are going to be using a pedestal in the bathroom, so the supply will be visible, causing even more issues. The 2" DWV uses a bunch of space here as well. I do have the possibility of coming in from the side instead of where you see the PEX coming in now. I can make the bath lav work, but only by essentially extending the supply from center line distance to 6" both sides. This will still all be under the pedestal bowl, just not as tight as is standard (to the center). I assume, while not necessarily standard, that there is no problem with this.

    However, if I do this, I will essentially be left having to put both hot and cold supply lines on the same side of the drain as each other (so instead of the drain being in the center, it would be to the left or right of both supplies). Aesthetically, I am not worried about it too much as it will always be in the under sink cabinet and will probably have things store in front of it. Is there anything in IPC/IBC code that disallows me doing it this way? If so, I have no clue how I will be able to do it otherwise.

    A few other items. Due to tight space constraints, I may have to tee off the hot and cold supplies under the floor in between the joist and then travel up for the fixture stub outs. I plan on feeding with PEX, but then using copper for the fixture stub outs. I am not sure how close to the drywall a copper pipe can be run, but with the 2" DWV, I have basically just barely enough room for the copper to run in front of it.

    Also, pay no attention to the way the supply lines are run now. Is only temporary until I am ready to re-pipe here in a few days. Also, that fully cut-and-scabbed stud is not my doing! When I opened the wall up, I found that this is actually how the original builders must have done it way back in 1943. I have since fixed it by taking this stud out and putting in a new one but that was before I took this picture. Thanks everyone!

    [​IMG]
     
  2. shelzmike

    shelzmike Member

    Joined:
    Jan 8, 2020
    Location:
    Virginia
    Well, no one ended up responding to my question. BUT, I am sort of actually glad no one did as it left me to go back and think harder about it. For posterity, here is what I came up with. It works great and is solid. This was about the only way I could figure out how to do it with the hot and cold on the proper sides and positioned on each side of the respective drain pipe.

    Try not to be too hard on the soldering. This project is the first time I have ever done so in my life. I practiced quite a bit and researched a TON and it turns out it really isn't terribly difficult, its just that you can tell the difference between a beginner and a pro based on the result of technique. I soldered my entire shower/bath valve situation and had no issues. The first time I pressure tested this sink supply, I did have a leak on the cold side of the bathroom right at the sweat pex fitting. It is now fixed now and working well. Note: While you can't see it from the pics, the hot supply in the middle has a tee that has the hot going into the kitchen as well.

    [​IMG]

    [​IMG]
     
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  4. James Henry

    James Henry In the Trades

    Joined:
    Jul 23, 2019
    Occupation:
    Plumber
    Location:
    Billings, Montana.
    It doesn't take long to learn how to solder. You did good.
     
    Last edited: Mar 25, 2020
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  5. plumber69

    plumber69 In the Trades

    Joined:
    Jun 20, 2014
    Location:
    Prince Rupert, British Columbia
    Lots of times ill put the supply lines one above the other. Usually never remember which is hot and cold but thats a simple solution
     
  6. NDL

    NDL Member

    Joined:
    Dec 27, 2017
    Location:
    Charlotte, NC
    That's what I thought.

    Nice neat job on the soldering, OP.
     
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  7. shelzmike

    shelzmike Member

    Joined:
    Jan 8, 2020
    Location:
    Virginia
    Thanks to everyone. This sub is by far one of the best resources online for us DIYers of any ability level. I don't know why I always was hesitant about copper soldering but you are right it really isn't that hard at all. In fact I really like it. I do love PEX for the branches but it makes a lot more sense to me for rigidity to use copper at the fixtures.
     
  8. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    I was always taught that hot was high and cold was low if it was going to be run in walls or along beams. I still would do that if I were stubbing out in a vertical fashion.
    I remember one time my apprentice asked if he could flip which one was high along a beam, and not wanting to be a jerk, gave him the okay but told him he better not forget he had flipped it.
    He flipped it, and then he had to cut out pipe and fittings and fix it. Anyway, to this day, it's always hot high, cold low.
    Think about how you run a bathroom wall. The toilet supply is low anyway.
     
  9. shelzmike

    shelzmike Member

    Joined:
    Jan 8, 2020
    Location:
    Virginia
    I may have totally failed to me room this, but the challenge part of it is that my wife insisted on a pedestal sink and I wasn't sure vertical alignment would have looked good, plus not only would it be vertical, it would have also been flipped on the kitchen side. I sort of like the way it turned out, after all.
     
  10. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    What you did was fine. Do you have a supply for a dishwasher there too?

    The hot / cold thing is more important when plumbing an entire home. That way whoever jumps in on it doesn't have to think or ask questions.

    Now with PEX, you can use different colors.
     
  11. shelzmike

    shelzmike Member

    Joined:
    Jan 8, 2020
    Location:
    Virginia
    No dishwasher supply. Our kitchen is too small for a dishwasher and cabinet space is scare, so we don't even have a good way to put even one of the half size ones. We have hand washed 16 years. It's really not a big deal honestly. Washing dishes is good thinking time : )
     
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