Adding laundry/2 sinks- venting questions with kindergarden drawings

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by onlyincali, Sep 16, 2017.

  1. onlyincali

    onlyincali New Member

    Joined:
    Sep 16, 2017
    Location:
    Southern California
    Hi guys, thanks for taking the time to look at this, I've been lurking this forum forever and have learned a lot but I have some very elementary plumbing questions to clarify before knocking this next project out.

    I'm looking at adding a laundry room upstairs and a kitchen sink in the basement below. I have a couple questions as its been a decade or so since I've done much plumbing. Luckily I have an existing 2" vent pipe which should support roughly a 20 or 24 fixture load IIRC. My concerns, however, are with my layout. Am I overlooking something dumb?
    1. I'm pretty sure I need to add a vent to the laundry room sink...right? If so, I'll just tie in above with the other new vent.
    2. Is the basement kitchen sink (below the washing machine) at risk for having the p-trap siphoned or will it be ok as a "wet vent", sharing the laundry room drains as a vent?
    3. If I need to make a horizontal run of about 6 feet with the 2" washing machine drain line, do I need to fir the wall out to 2x6's? It seems like cutting a hole for 2" piping through 4 studs will be too much structural compromise...... Am I overthinking this?

    Orange is proposed new install, green is existing 2" vent pipe
     

    Attached Files:

    Last edited: Sep 16, 2017
  2. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    Kitchen sinks and washers don't wet vent. Too much water for that. A washer will siphon a sink below .
    Only bathroom groups located on the same floor can use wet venting.
    Any vent on a lower floor needs to be revented on the floor above, six inches above the upper floor flood levels. That's normally 42" above the floor.
     
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  4. onlyincali

    onlyincali New Member

    Joined:
    Sep 16, 2017
    Location:
    Southern California
    Thank you Terry. Would the below additions make this work?

    Thank you again for your time and this awesome forum.
     

    Attached Files:

  5. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    Closer but no cigar.
    The waste from above should enter below the lowest fixture.

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    Last edited: Sep 17, 2017
  6. hj

    hj Moderator & Master Plumber Staff Member

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    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    That lower vent connection does absolutely nothing and the lower sink is still not vented.
     
  7. onlyincali

    onlyincali New Member

    Joined:
    Sep 16, 2017
    Location:
    Southern California
    Thanks guys and thank you for the diagrams Terry, that pretty much cleared up all confusion(I think). I think I finally have it figured out thanks to you guys. Updated picture below.


    Second question- A neighbor who claims to be a plumber just stopped by and I had him take a look at the bathroom that I am renovating upstairs. He claims the entire bathroom can be wet-vented through the 2" sink drain/vent. There is a toilet Upstream of the vent and a bathtub downstream of the vent, both within 4 feet in either direction. Wouldn't flushing the toilet siphon the tub p-trap since the vent is upstream? Now I'm really confused. Childs drawing of neighbors proposed layout below.

    Thanks! final laundry.jpg up bath.jpg
     
  8. onlyincali

    onlyincali New Member

    Joined:
    Sep 16, 2017
    Location:
    Southern California
    Sorry to bump this pathetic thread again, last 2 questions...I hope. :)

    1. On the bathroom layout directly above, is it safe to assume the neighbor is wrong and I actually DO NEED a vent on the trap arm of the tub because it is downstream of the wet vented sink and will be siphoned when the toilet is flushed?

    2. Is the toilet good without its own vent providing the sink drain/vent is 3 feet away?

    Thank you again.
     
  9. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    The tub can come off the lav line but not the wc (toilet) line. As drawn now, there is no vent on the tub.
    The lav needs to be 2" on the wet vent portion to vent the tub and the toilet.
     
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