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P-trap extensions?

| Posted in Construction Techniques on November 5, 2003 08:58am

Hi. I’m installing a new deep double bowl sink in existing cabinetry. With the height of the drain line in the wall there’s barely enough room for the tee tailpiece and not enough room for the dishwasher tailpiece. Is it ok to add an extension to the drain side of the p-trap so  it is lowered enough to allow for the d/w tailpiece? Water would then be above the level of at least one of the trap nuts, but ripping out cabinetry and wall to lower the drain line is not an option. Thanks.

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  1. SledBC | Nov 05, 2003 11:01am | #1

    If I understand you correctly, build your own system out of 1-1/2" pipe and instead of putting a Dishwasher tailpeice in, use a T-Wye in place of a 90 under one of the tailpeices and tie into the end of it with your D/W. You can buy a 1-1/2" threaded end cap and a 1/2" brass nipple for the D/W. 

    I hope that makes sense...its late :)

    Darren

    http://www.LDHindustries.com

    1. clintcarter | Nov 06, 2003 08:20am | #5

      Thanks Sled. I have ordered custom strainers for the sink, the current are temporary, so will look into it when they arrive. The rest of the system is such nice chrome pipe, would like to keep the look...

  2. User avater
    Mongo | Nov 05, 2003 12:42pm | #2

    I had the same predicament just last week. Changed to a deeper bowl, as well as undermount sink vs drop-in...plus lower than normal 8/4 teak countertops.

    I found extra room by going with a lower profile sink strainer for the new sink, which saved about 3/4", as well as a different sink strainer/dishwasher tailpiece. The wye for the dishwasher was closer to the top of the tailpiece, that saved another half-inch.

    1. clintcarter | Nov 06, 2003 08:25am | #6

      Thanks Mongo. The sink is a Rohl fireclay model that requires the extra long strainers. As I note above, I've ordered the Rohl strainers and will deal with this when they arrive. I'd love to find the d/w tee with the nipple closer to the tailpiece top; do you have a brand name?

  3. steve | Nov 06, 2003 05:08am | #3

    another suggestion, eliminate the tail piece and trap adapter by using a threaded pipe fitting directly to the basket like threaded elbow at both baskets to make the crossover, install a dw wye in the crossover and a tee to the trap, seen it done and it raises the crossover about 2 inches

    caulking is not a piece of trim

    1. clintcarter | Nov 06, 2003 08:16am | #4

      Thank you Steve and others for your info. Steve, I'm not sure what is meant by 'basket like threaded elbow' but if I get your intent, with the fittings on the crossover, it's not possible here because the drain opening is too close to one of the strainers. Thanks.

      1. steve | Nov 07, 2003 02:42am | #8

        what i meant was an elbow that threads directly onto the basket/strainer, use one on each strainer and join together with a tee or a four way what ever dont know what that would be calledd maybe a cross???

        should save a few inchescaulking is not a piece of trim

  4. clintcarter | Nov 06, 2003 08:32am | #7

    Hi. I'm replying to myself to ask part of my question again:

    Has anyone had experience with adding an extension to the drain side of a p-trap? Such that the trap is lowered 2-3"?

    Thanks everyone for your help.

    1. sungod | Nov 07, 2003 03:00am | #9

      This is a very common problem.  The old time solution was to use a saxton trap that came out of the wall, then turn and go down deeper than normal.  Big Problem!  What this would do to the garbage disposal is have the grinder immersed in water all the time.  The bacteria and smells would be there all the time.

      Solution is to sawzaw out the sanitary "T", install a plastic one with two nohub couplings.

    2. OneofmanyBobs | Nov 07, 2003 03:02am | #10

      Adding an extension to the exit side of the trap is effectively making a larger trap loop.  More standing water in the trap, possibly more potential for it to clog.  I would think that an inspector might reject an installation like that.  From a practical standpoint, it would drain and should not siphon.  I've seen a lot worse things done.

      1. clintcarter | Nov 07, 2003 07:43am | #11

        Thanks everybody. This is a wonderful system. (The forum, not my drain...) When I get the new strainers I'll look at Steve's elbows as a solution; if that doesn't fly I think the extension will.  Inspector?  Whazzat??

        1. steve | Nov 07, 2003 10:38am | #12

          the threaded elbows WILL work and pass inspection at least they do in ontario, the only reason we have tailpieces and trap adaptors is to allow flexibility in the verticle directioncaulking is not a piece of trim

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