Should I add another vent?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Procarp john, Mar 22, 2021.

  1. Procarp john

    Procarp john In the Trades

    Joined:
    Mar 22, 2021
    Location:
    Bay Area
    Glad to be here first time posting, quick question: I have the WC, dry vent, sink and then shower drain. Should I add another vent before exiting my drain line out of this little remodel?
     

    Attached Files:

  2. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Which code are you under, IPC or UPC? Depends on what state you are in; if "Bay Area" is the SF Bay Area, then that's CA and the UPC.

    So the first riser (closest to WC) is meant as a dry vent, and the second is for the lav? You can't take off a dry vent flat like that. If you are under the IPC, horizontal dry vents under the slab are prohibited; if you are under the UPC, they are allowed if structural conditions preclude keeping your vent vertical up to the point 6" above the fixture flood rim. Not sure that would apply in your picture; if it does, you'd need to do the vent takeoff with a wye rolled up 45 degrees above horizontal, then you could use a 60 to go horizontal and perpendicular to the drain. Which might not fit under the slab with your current drain elevation.

    However, you can just omit that dry vent, and the lav can wet vent the WC. The lav vent and drain (excluding the trap arm) would need to be 2" if under the UPC for wet venting, and the horizontal run from the closet flange to the lav coming in is limited to 6'. The IPC is OK with 1-1/2" and doesn't limit the distance from the closet flange.

    That just leaves the shower, and there's two issues. One is that you have a lot of bends in there; if you move the wye downstream you could probably do it with a single street 45 in the wye branch inlet and then hit your trap elbow outlet. The other is that if you are under the IPC, the lav can wet vent the shower under the arrangement shown. But the UPC requires that the WC be the last wet vented fixture; i.e. no part of the WC drainage path can be a wet vent.

    So if you are under the UPC, you'll need to either dry vent the shower before it joins the common drain, or dry vent the WC and keep the WC drain separate from the lav until downstream of the shower/lav juncture, which allows the lav to wet vent the shower. I've got some thoughts on how to do the latter, but it would require cutting more concrete.

    Cheers, Wayne
     
    Procarp john likes this.
  3. Sponsor

    Sponsor Paid Advertisement

     
    Procarp john likes this.
  4. Procarp john

    Procarp john In the Trades

    Joined:
    Mar 22, 2021
    Location:
    Bay Area
     
  5. Procarp john

    Procarp john In the Trades

    Joined:
    Mar 22, 2021
    Location:
    Bay Area
    Thanks so much Wayne
     
  6. Procarp john

    Procarp john In the Trades

    Joined:
    Mar 22, 2021
    Location:
    Bay Area
    All right I had a long day at work, and wanted to take time to reply. So the first riser is a dry vent rolled up to 45 or close too it. Second is the lavatory. and from that first riser which is the dry vent right after the water closet to the p-trap on my shower is 5 ft. Also I got finished flooring both sides of me and gas lines that are keeping me where I'm at. If that dry vent after the water closet isn't suffice could I go ahead and put a 3x3x2 combo and run it up that exterior wall? After the shower drain. I was hoping the first riser (dry vent) would cover my shower drain. Normally I would have ran the lavatory and shower drain on a 2 inch line and tied it together before I tied into the 3-in main. And yes Wayne I'm in the Bay area and I want to thank you again.
     
  7. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    So I assume you mean the SF Bay Area, and you are under the UPC.

    - The biggest issue is that you don't have an acceptable vent for the shower. The UPC doesn't allow fixtures downstream of the WC to be wet vented. If you are able to redo the shower drain connection so that you take a dry vent off the shower trap arm before it joins the 3" line, that would work. If you want to wet vent the shower, you'll need to reconfigure things, see below.

    - On the WC dry vent, it's a judgement call on whether the vent is allowed to go horizontal below the slab; it's required to stay vertical unless "structural conditions" preclude that. If your inspector is agreeable to allowing it horizontal below the slab, what angle bend did you use in the wye side inlet? If that's a 60 and the wye is rolled up at least 45 above horizontal, that's the correct way to do it, and I'm just misinterpreting the picture. But if the bend is a 45, then there's no way that the wye is rolled up enough.

    - If the WC dry vent is acceptable, then you could wet vent the shower by rerouting things, such as per the mark up below. The red line is the proposed layout drawn on top of your existing layout. But if the WC dry vent is not acceptable, then you need to use the lav to wet vent the WC, and you'll have to figure out how to pull a dry vent off the shower trap arm.

    Hope this helps.

    Cheers, Wayne

    IMG_20210322_161804809_markup.jpg
     
    Procarp john likes this.
  8. Procarp john

    Procarp john In the Trades

    Joined:
    Mar 22, 2021
    Location:
    Bay Area
     

    Attached Files:

  9. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Looks good to me!

    Cheers, Wayne
     
    Procarp john likes this.
  10. Procarp john

    Procarp john In the Trades

    Joined:
    Mar 22, 2021
    Location:
    Bay Area
    Alright!!
    Thanks Wayne. doing it right is priceless.
     
Similar Threads: Should another
Forum Title Date
Plumbing Forum, Professional & DIY Advice PEX angle stop replacement. What should I do!? May 11, 2021
Plumbing Forum, Professional & DIY Advice How much should a picote process cost in Hemet Calif May 11, 2021
Plumbing Forum, Professional & DIY Advice Simple Reason why DIY shouldn’t DIY. Apr 24, 2021
Plumbing Forum, Professional & DIY Advice Connecting PVC to Cast Iron Elbow that is Tilted / Should I replace Cast Iron Pipes? Mar 18, 2021
Plumbing Forum, Professional & DIY Advice Installing Water Line for Humidifier - Not Sure if I Should Attempt Sweating or Use a Sharkbite Feb 13, 2021

Share This Page