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Thread: Shower drain P-Trap question

  1. #1

    Default Shower drain P-Trap question

    I'm building a larger shower in our master bath and need to move the drain. Because of the new drain location, I either need to drill a hole through a beam under the floor for the drain pipe to go through, or I can try and go under the beam. I would prefer to go under, since drilling a hole in the beam would be difficult due to its location.

    Here's a crazy concoction I came up, would this work or should I just bite the bullet and get a hole through the beam and use a regular p-trap?

    Thanks!
    Christian

  2. #2
    Plumbing Designer FloridaOrange's Avatar
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    How big is that thing?? I think you should do it right even if it's not the easiest way.
    Besides, my codebook has this and I'm pretture sure your's does too.

    2007 FPC 1002.4 Trap Seals. Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inches (102 mm),
    Matt
    Semi-professional plumbing designer
    Enjoying life in SW Florida

  3. #3
    Plumber krow's Avatar
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    I would certainly NOT drill any holes in any beams. Find another way without drilling your beam

    The set up that you have will work, but it is against code

  4. #4

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    Thanks guys, I'm not a plumber so I don't have a code book. I just measured from the bottom of my makeshift trap to where water would flow out and the distance is 7". I'm not worried about being code compliant, but I would like to avoid troubles (naturally). Is that 3 extra inches going to cause me grief?

    Thanks again!

  5. #5
    Master Plumber nhmaster's Avatar
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    Why are you not worried about being "code compliant" ?

  6. #6
    DIY Senior Member TedL's Avatar
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    If you're going under the beam, why the offset before the trap?
    Is it really a beam, or just a 2x? joist? No access below??
    Why not buy a trap (made and sold as such) that will be code compliant?

    You're dealing with code issues that are crucial to things working for the long term.

    Post a pick of the setup. You may get a simpler recommendation.

    Here's a code applicable to several states.
    http://publicecodes.citation.com/st/index.htm

  7. #7

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    Good idea, here's some more pics...

    I was basically just trying to tie into where the old drain went (which was in the middle of the open square in the subfloor), but I see I can also stay on the left side of the beam without having to under it and run straight to main sewer pipe that all of the other nearby plumbing drains into. So perhaps I should consider adding in a T-connector there and avoid the beam altogether?

    Anyway, here I've dry fit that crazy p-trap:


    (point of clarification on what I labeled 3 1/2" sewer pipe... it's actually 2" pipe what you see in the picture, but just off to the left of the photo there's an adapter that opens it up to a 3 1/2" pipe.)


  8. #8
    Master Plumber nhmaster's Avatar
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    No matter how you run the pipe when you drop into the main you need a vent going up else you have an s trap. Also whn you tie into the main it must be at least 10 pipe diameters from any vertical stack.
    Last edited by nhmaster; 08-11-2009 at 06:31 AM.

  9. #9
    Mechanical Engineer loafer's Avatar
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    Is it possible to run a new drain line parallel to you existing and then drop down below the joists when you reach the far wall of the basement?

    You can put a hole in that beam, but there are restrictions as to where and how big. These are some general guidelines below, your local code may be different:

    -The hole can be no larger than 1/3 the joist/beam depth. In your case that limits you to a 3 hole. Always keep the hole as small as possible. In you case I would try and keep it under 2.5 and if this is tub drain use 1.5 pipe so you can drop to a 2 hole.

    -The hole must be centered in the depth of the beam

    -You can not put any holes or notches in the middle 1/3 of the joist/beam span. The reason for this is the center span of the beam is the region of maximum bending stress and shear stress

    -You can not notch the tension side of a beam that is greater than 4 in width. Your beam is only 3 wide, but I would still avoid notching the tension side of the beam. IMHO notching the tension side of any joist or beam should be avoided.

    The trap needs to be vented as previously mentioned.

  10. #10

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    There is a vent right where the drain ties in to that main pipe, you just can't see it because of the angle of the photo.

  11. #11
    In the Trades kordts's Avatar
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    I hate to get involved with this, but I am compelled to say, why does the drain have to go on center? If it's a custom shower, the drain can go anywhere.

  12. #12

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    Quote Originally Posted by kordts View Post
    I hate to get involved with this, but I am compelled to say, why does the drain have to go on center? If it's a custom shower, the drain can go anywhere.
    I'm installing a Wedi shower, so the location of the drain in this case is being dictated by their pans and the beam that's running under the floor. Otherwise yes, I probably would have put the drain elsewhere.

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