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Garage Utility Sink P Trap

NoQuarter | Posted in General Discussion on June 19, 2007 06:52am

I plan to install a utility sink in my garage. The wall where the sink is located is an interior wall with the laundry room on the other side.

I intend to use a freeze proof faucet such as this one from Woodford (http://www.woodfordmfg.com/Woodford/Wall_Faucet_Pages/model-22.htm )

I am interested in a method for installing the P trap in such a way as to prevent it from freezing as well. Then I can use this sink year round instead of needing to winterize the trap and not using the sink for months at a time.

Since the faucets will already extend though the wall for the supply connection, can I do the same with the P trap and still be in code? (I will check with local inspector of course). So the drain line from the sink extends at an angle through the wall- THEN into the trap that is located on the interior side of the house.

 

Jim

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Replies

  1. User avater
    Sphere | Jun 19, 2007 06:58pm | #1

    Vent it properly. And it won't FU in a heated space. I do not know why, but it works.

     

  2. peteshlagor | Jun 19, 2007 07:00pm | #2

    Where are you?

    I'm wanting to do the same here in Denver and find my garage doesn't ever get that cold to worry about freezing.  What's your's like?

    One suggestion I heard is to have a 75 - 100 watt bulb wired up inside the sink cab.

    Anyway, when I do mine, I was thinking of putting the trap inside the insulated house wall.  Cut out the sheathing behind the garage cab, do the plumbing.  Replace the insulation about the pipes, Stick a piece of foam in the replace the sheathing while running the pipe strait out.

    Is that bad?

     

    1. NoQuarter | Jun 19, 2007 08:30pm | #3

      I am in Northern Indiana. The Temps get to ~0deg a few weeks (or longer) in the winter. My garage doesn't get too bad most of the time but a few weeks of that and an opened garage door may cause some anxiety for me. I'd much rather have a "worry free" installation if possible.

      The venting issue completely slipped my mind when I thunk up the idea of putting the trap on the interior side of the wall.

      I'm now thinking this won't work. After the trap, the line would need to drain though the floor of my laundry room then into the basement to tie into the waste pipe. The problem with this is that then it becomes an "S" trap (and not a P trap) which would cause the water to be siphoned out of the trap.

      I don't think I would consider putting the trap inside the wall (I think that was what you described). The trap needs to be accessable for maintenance.

       

      1. plumbbill | Jun 21, 2007 06:19am | #15

        I don't think I would consider putting the trap inside the wall (I think that was what you described). The trap needs to be accessable for maintenance.

        Not really, it does make it easier, but how many floor drains, shower drains, tub drains, & floor sinks have you seen with accessible P traps?

        The hardest thing in the world to understand is the income tax.

        -- Albert Einstein

        1. FrankDuVal | Jun 21, 2007 07:49am | #16

          "but how many floor drains, shower drains, tub drains, & floor sinks have you seen with accessible P traps?"And how about most laundry rooms? Most everything here uses those nice in the wall boxes for the washing machine. Every one of those has an in the wall trap (that I have seen...)Frank DuVal

          1. plumbbill | Jun 21, 2007 08:40am | #17

            Yup those too, thanks forgot about those.

            The hardest thing in the world to understand is the income tax.

            -- Albert Einstein

          2. NoQuarter | Jun 22, 2007 12:36am | #19

            So many examples of "hidden" traps!

            I suppose I was thinking along the lines that it is a sink and we often drop things down sinks more often than we would a washing machine or floor drain.

             

            Jim

          3. FrankDuVal | Jun 22, 2007 06:28am | #20

            "we often drop things down sinks more often than we would a washing machine or floor drain."Well, that is very true, so if you hide a sink trap you need a permanent in place strainer! Also, only hide a 2" trap and the clogging will happen less often.Frank DuVal

      2. peteshlagor | Jul 12, 2007 12:29am | #21

        Just discussed my plans with the BI about the garage sink.

        He is unconcerned about freeze proof faucets and/or drainlines with the sink backed up to the house's building enveolpe.

        He (and another BI boss I talked to at the desk) only seemed concerned about the penetration thru the firwall.  Using proper fire caulking and/or special bushings about the pipes would make them happy.  So here in Denver, no big deal.

         

        1. NoQuarter | Jul 12, 2007 01:48am | #22

          Thanks for taking the time to post an update!

          Jim

           

           

  3. DanH | Jun 19, 2007 11:52pm | #4

    Simplest thing is to build a vanity of sorts for the sink, and make it part of the "heated envelope". You can also wrap the trap with heat tape.

    So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
  4. User avater
    BillHartmann | Jun 19, 2007 11:58pm | #5

    I don't think that it is a problem.

    You have a limited amount of water and it is open on each end so it can expand if it freezes.

    That is unlike a run of pipe that has pressure and can freeze a large enough area to block the center and have it expand and crack the pipe.

    I have similar setup. I am in Kansas City. In Dec of 89 we had about 2 weeks that got down to -20. I was in Louisville at the time, where they where having similar weather, and when I got back there was a sheet of ice out the garage door because a riser has frozen and broke.

    But the trap was fine.

    .
    .
    A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
  5. User avater
    jonblakemore | Jun 20, 2007 03:06am | #6

    One method would be to use a PVC trap and do nothing special. If it freezes and breaks, you're out maybe $15 and have a small puddle of water.

    If it doesn't break then you don't have to worry about it.

     

    Jon Blakemore

    RappahannockINC.com Fredericksburg, VA

  6. User avater
    MikeMicalizzi | Jun 20, 2007 03:53am | #7

    Jim,

    I agree with Jon Blakemore's post.

    But just out of curiosity, I looked up your question regarding the "maximum length a tailpiece can be, prior to the P-trap", I'm not a licensed plumber, but it looks like 30" (source - Code Check Plumbing)

    1. Shacko | Jun 20, 2007 07:00pm | #11

      I think I may have missed something on the original post, but he was talking about going thru a wall. Most code references pertaining to a tail-piece mean a vertical drop. Going horizontal creates what is called a running trap, most of the time a no-no. Info. only.

      1. User avater
        MikeMicalizzi | Jun 21, 2007 04:13am | #12

        Shacko,

        I'm probably opening a can of worms by trying to decipher the code, since no two people view it the same, but anyway.....

        I attempted to attach a photo of the diagram I was looking at from the code book which illustrates the 30" tailpiece length. They show a double sink with the sink on the right being the furthest from the trap. The code indicates that 30" is the longest horizontal distance the basket drain could be from the trap. Here's what it says under the section entitled "Fixture Tailpieces": One center trap may serve up to three sinks, max 30in apart. So is it wrong to assume that they're labeling that horizontal run of pipe (between the basket and the trap) a tailpiece?

        Maybe that bit of code is only meant to cover double or triple sink set-ups 

        1. Shacko | Jun 21, 2007 06:08pm | #18

          Don't feel bad that the plumbing code is hard to decipher; a lot of plumbers don't understand it. Getting back to the questions, a tailpiece is a vertical drop from the fixture or device that is connected from the trap, most of the time a max of 24in. The horizontal distance means that you can't exceed 30in. when hooking up a max. of three sinks. This does get tricky, if you want to pursue your quest for info. get a copy of the definitions, they do help. Lots of luck........................................
          "If all else fails, read the directions"

  7. cliffy | Jun 20, 2007 04:13am | #8

    I live in Northern Ontario and we get plenty of winter.  I have a utility sink in my  garage.  It is against the wall that backs into heated area of the house.    I have a regular laundry tap on the sink and I keep a thermometer on the wall just above it.  When it is really cold out I run the water a trickle to keep it from freezing.  The p trap is inside on the warm side of the wall.   The drain is vented and works all year fine.

    I use this sink to feed a hose every winter when I build my kids a rink outside beside the garage.

    Have a good day

    CLiffy

    1. NoQuarter | Jun 20, 2007 03:48pm | #9

      Great comments everyone. They have all helped in my decision.

      On the trap, I'll go with PVC and if it happens to break, no big deal.

       

      Jim

      1. User avater
        BossHog | Jun 20, 2007 04:23pm | #10

        If the sink backs up to a heated space, I wonder if you could enclose the front and sides of the thing to help "borrow" some heat from the house. Maybe even enclose the whole thing in a cabinet. That in itself wouldn't keep t from freezing. But it might help some.
        Women are like Weather. Nothing can be done to change them.

      2. cliffy | Jun 21, 2007 05:20am | #13

        If it breaks and your not home, big deal.  I'm assuming you are on a municipal sewer system.  Until you discover the break you will be filling your garage with all kinds of nasty smells and gases.  

        Something to think about!

        Have a good day

        Cliffy

  8. grpphoto | Jun 21, 2007 05:39am | #14

    You don't need to freeze-proof a trap. The reason you need to freeze-proof the supply lines is that water expands when it freezes. With supply lines, it has no place to go and breaks the pipes, but with a trap, there's only a few ounces of water in there and plenty of surrounding space.

    George Patterson
  9. User avater
    PeteDraganic | Jul 12, 2007 02:40am | #23

    Assuming that freezing is a legitimate concern in your garage, I would suggest either heat tape on a thermosensitive switch or putting the trap downline where there is heated space.  You can trap it in the basement just fine and it shouldn't siphon.

     

    http://www.petedraganic.com/

  10. mrtappy | Jul 18, 2019 07:29am | #24

    This is a good solution for garage heating.

  11. LukeTaylor | Jul 18, 2019 07:50am | #25

    You need to call a specialist to check your garage.

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