Trap arm length

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jdkimes, Nov 12, 2004.

  1. jdkimes

    jdkimes Engineer

    Messages:
    181
    Location:
    Littleton, CO
    I'm putting in a bathroom vanity sink.
    The rough drain is coming out of the side of the wall. The cabinet is 60" and the sink is offset a little, so the middle of the sink is about 36" from the wall where the 2" rough drain comes out.
    My question is: Should I extend this 2"-pipe a foot or so before going to the trap arm or should I make the trap arm really long?

    If I do extend it should I just glue union fitting or is there another way that's better?
  2. LonnythePlumber

    LonnythePlumber Plumber, Contractor, Attorney

    Messages:
    319
    Location:
    Wichita, Kansas
    Trap Arm

    The trap arm is that distance from the trap to the vent. Extending the 2" pipe will still be considered a trap arm. You can cement on a coupling. You only need to be 1 1/2" so you might want to use a 2 x 1 1/2" coupling. You will also need to add some support by the bowl. Strange that a 2" pipe was roughed out.
  3. jdkimes

    jdkimes Engineer

    Messages:
    181
    Location:
    Littleton, CO
    Is there an advantage to having the trap arm (and trap) 1 1/2 vs. 1 1/4?
    The couplings come in a 2" to 1 1/4 or to 1 1/2.
    I assume that the tailpiece on the sinks are 1 1/4 and I can use a compression slip fitting that will take it from 1 1/4 to 1 1/2 on the trap and arm.

    Seems like a bigger pipe would always be better.
  4. LonnythePlumber

    LonnythePlumber Plumber, Contractor, Attorney

    Messages:
    319
    Location:
    Wichita, Kansas
    Thanks Terry

    I notice the new avatar like on john bridges site. I presume Terry did that and I thank you terry. I agree with the 1 1/2"
  5. jdkimes

    jdkimes Engineer

    Messages:
    181
    Location:
    Littleton, CO
    Thanks for the avatar

    Yes, thanks for changing my avatar.
    I'll have to start a new plumbing project so I can keep checking this forum, since I'm almost done w/ my basement bathroom finish.
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