Will this drain system work?

Discussion in 'Remodel Forum & Blog' started by Nelsmarc, Jun 17, 2009.

  1. Nelsmarc

    Nelsmarc New Member

    Messages:
    3
    Hi, I am a novice at plumbing but am really enjoying the learning process. My 2nd bathroom/laundry room is only roughed in, and I am in the process of building it out. I am concerned with how many fixtures I have attached to a single 2" drain pipe, and I was hoping you guys could give me some advice as to weather or not this system would work. Thank you for your help.

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  2. FloridaOrange

    FloridaOrange Plumbing Designer

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    1,317
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    SW Florida
    Need a vent at the washing machine and a vent at the shower, Florida and IPC you cannot vent a bathroom fixture with a non-bathroom fixture. What jurisdiction are you under? Some jurisdictions may require a 3" to the washing machine.
    Last edited: Jun 18, 2009
  3. jimbo

    jimbo Plumber

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    8,997
    Location:
    San Diego
    Most place...you cannot tie the washing machine into the sink/shower line. The washer must drain alone into a 3" lateral. And you appear to have a section of flat vent under the floor.
  4. Nelsmarc

    Nelsmarc New Member

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    3
    Thanks for the help. Maybe I don't fully understand wet vents, but I thought that the vent for the bathroom sink would suffice as a wet vent for the Washing Machine and the Shower. My juristiction follows the IPC. I guess they changed the code since 1979 because the existing drain for the Washing Machine is a 2" pipe. As far as having a flat vent under slab, is that bad? It is not only a vent but the drain for the Kitchen Sink. Tonight I'll change my layout so that the Washing Machine drains seperately.
  5. FloridaOrange

    FloridaOrange Plumbing Designer

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    IPC did change the line size to the washing machine to 3", and Florida code which is heavily based on IPC also started requiring the separation between bathroom and non-bathroom venting about 2 revisions back.
  6. Nelsmarc

    Nelsmarc New Member

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    Florida Orange, I don't doubt that you are correct from the quote "you cannot vent a bathroom fixture with a non-bathroom fixture", but I don't understand why? Is it just because thats what the code says or is there a functional reason why this would be a bad idea? It seems to me that as long as air is being supplied by a vent, it shouldn't make a difference which vent the air is coming from?

    Here is a modified schematic with the Washing Machine on a separate 3" drain (but still sharing a vent with a bathroom fixture). Will this design work?

    Attached Files:

    Last edited: Jun 18, 2009
  7. FloridaOrange

    FloridaOrange Plumbing Designer

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    Location:
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    The part of the code which requires the separation has nothing to do with function, previous codes we were able to "cross-vent", someone on some committee thinks it's safer I guess. I think it popped up in the 2001 code. This is the wording, part of Chapter 9, section 910: Only the fixtures within the bathroom groups shall connect to the wet-vented horizontal branch drain. That's from the Florida Plumbing code which is almost identical to IPC.


    I'm having trouble acutally seeing the arrangement, specifically the angles some of your fixtures are on, can you post a plan view(where are the walls located)? I will give it a shot until then. It looks like everything is fine but you can combine the sanitary at the first floor, it just has to be downstream of a bathroom wet vent (the sink/shower part of the system).
  8. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    vent

    NEver heard of the regulation to "not wet vent a bathroom fixture with a non bathroom fixture", and have NEVER had any inspector try to enforce it. The biggest problem you will probably have is that the washing machine drain could overload that horizontal 2" pipe, depending on how long it is, and back up into the shower. I have had it happen with a floor drain, which is just like a shower, and had to install a "back flow preventer" into it.
  9. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    That's the interpretation I was given for that code. As stated the quote is from 2007 Florida Plumbing Code - I don't have IPC. Do you have IPC in AZ?
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