Help Needed: Bathroom Plumbing Layout

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by JoeNW, Jul 20, 2021.

  1. JoeNW

    JoeNW New Member

    Joined:
    Jul 20, 2021
    Location:
    Oregon
    Hi Everyone,
    I'm remodeling my old house and am not a plumber. I've read on the forums and tried to make sense of the code check book. Of all the trades I've had to do during this remodel - plumbing is the hardest and I have lots of respect for the problems that plumbing professionals solve every day. I've drawn out my system and would really appreciate some feedback. Technically my area falls under UPC, but if there is an IRC compliant solution to any issues in my diagram it might work. The local inspector has been understanding with some things given how bad everything was before I started fixing things. The space is tight and the house framing is weird, so I'm doing the best I can to get everything to right.
    Thank you for your help!
    Joe

    Walkthrough of the diagram:
    1) Tub and Toilet are wet vented. Is this ok? I'd like to run the vent up the wall between the tub and toilet and right through the roof.
    2) Clothes washer drain could fit in location "A" or "B", are either one of these ok?
    3) There is also a vent right where the main drain marked "To Septic" drops into the septic tank
    4) I haven't figured out where/if I need cleanouts other than right where the double vanity sink drains meet. This system is in the 1st floor and the pipes are accessible in the basement. Do I need cleanouts for this part of the system, or is access through the fixtures sufficient? I could fit one in right downstream of the toilet, or elsewhere if needed.
    Thank you for your help!

    Bathroom Drain Vent Diagram.jpg
     
  2. wwhitney

    wwhitney Well-Known Member

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    Mar 17, 2019
    Location:
    Berkeley, CA
    0) One requirement to bear in mind is that the aggregate vent area through the roof is required to be at least the same area as the minimum allowed building drain size, which would be 3" for a house with up to (3) WCs [or I think it may be 5 in Oregon]. That would be satisfied with (1) 3" vent, or with (2) 2" vents and (1) 1-1/2" vent.
    1) FWIW, the tub is dry vented and the WC is wet vented. The vent takeoff needs to be an upright combo.
    2) Either one is OK, but the clothes washer standpipe needs a vent (1-1/2" is sufficient), which is not shown.
    3) If all the fixtures are shown, that vent is not required.
    4) Not 100% clear on the cleanout requirements, but for the 3" line, convenient for a plumber would be to extend the 3" up to the tub vent, make the bottom of the vent 3", and put a 3" cleanout there. Then the vent could be 2" above the cleanout. The code requirements are here, Section 707:

    http://epubs.iapmo.org/2017/Oregon/mobile/index.html#p=95

    (although Oregon has recently adopted the 2021 version, not sure if there are any changes)

    Cheers, Wayne
     
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  4. Jeff H Young

    Jeff H Young In the Trades

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    Feb 27, 2020
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    92346
    joenw, you mention basement so I would put my clean outs down there one by the w/c and another where the double lavs are (if under 5 foot from lavs to main forget about a clean out) . So with the vents as Wayne said .
     
  5. JoeNW

    JoeNW New Member

    Joined:
    Jul 20, 2021
    Location:
    Oregon
    Wayne and Jeff, Thank you!
    0) I'll have the equivalent venting SA of 3" diameter across the whole system (kitchen not shown)
    1) Good to know. Might do a wye on it's back, with a 1/8 attached in order to make the turn, that's the same a combination wye right?
    2) I hadn't thought of venting the clothes washer. The washer machine drain will be within four feet of the vent stack, and I don't expect the washer machine drain to seal the drain hole opening completely. With this in mind, would the washer machine drain still need it's own vent?
    I appreciate the advice for the cleanouts too.

    Thanks again,
    Joe
     
  6. wwhitney

    wwhitney Well-Known Member

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    Mar 17, 2019
    Location:
    Berkeley, CA
    1) Yes
    2) Yes, every trap needs a vent.

    Wayne
     
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  7. Jeff H Young

    Jeff H Young In the Trades

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    Yes you still need a vent for wash mach. trap above the floor with a horizontal trap arm leading to santee which will have vent on top
     
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  8. Reach4

    Reach4 Well-Known Member

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    Sep 25, 2013
    Location:
    IL
    An AAV could be used to vent the p-trap under IPC, and some UPC areas have added local amendments to permit AAVs at least in some circumstances.
     
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  9. JoeNW

    JoeNW New Member

    Joined:
    Jul 20, 2021
    Location:
    Oregon
    Wayne, Jeff and Reach4, thank you. Those suggestions will fit well, I’ll need to check if I’m allowed to use the AAV for the washer.

    I found a potential issue with the location and drain of the toilet. I was planning to drain the toilet by dropping 8-10” vertically into the horizontal drain. Does this violate the following UPC 908.2 below? If so, to remedy it, would even 1” of horizontal pipe classify the drain as connecting horizontally? Or am I ok to drain the toilet vertically into the horizontal wet vent/drain? With the correct combo wye as discussed.

    UPC 908.2. (IRC 3108.1) “Fixture drains to horizontal wet vent must connect horizontally & independently, vertical connections require a dry vent”

    Thank you again!
     
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  10. Jeff H Young

    Jeff H Young In the Trades

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    good question on the w/c I havent looked at that lately but been discuseed at length in another thread some time back. I dont see an issue with function also this might have only been a CA code issue but I might play safe and lay the wye or combi on side serving the w/c looks like it should be easy enough. for some reason they dont like the W/c right over the top
     
  11. wwhitney

    wwhitney Well-Known Member

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    Location:
    Berkeley, CA
    To my knowledge, that text is not part of the UPC, nor part of any Oregon amendment to the UPC.

    So the next question is whether Oregon has adopted IRC Chapter 31. Up.codes suggests it has not, as it instead refers you to Oregon's UPC.

    In which case that text would not apply to your project.

    Cheers, Wayne
     
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  12. Jeff H Young

    Jeff H Young In the Trades

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    what I just saw from OPSC 2017 909.2 with a Oregon state interpretation mar 2019 said fixtures must connect horizontally . Sorry cant quite copy it, or verify this current. From a functional point I'd be confident but I get irked when I cannot totally know if its compliant .
     
  13. wwhitney

    wwhitney Well-Known Member

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    Location:
    Berkeley, CA
    The plot thickens. The interpretation Jeff is referring to:

    https://www.oregon.gov/bcd/codes-stand/Documents/interp-19-02-horizontalwetventing.pdf

    2014 OPSC 908.2 includes the text "Each individual fixture drain or trap arm shall connect horizontally to the wet-vented horizontal branch drain or shall be provided with a dry vent." That was very clear, but the 2017 OPSC does not have that text, nor does the 2021 OPSC (judging by a published list of changes that omits 908.2, as the 2021 OPSC is not currently available on iapmo.org)

    Now the interpretation above says that the fixture drains still have to connect horizontally. However, I completely disagree that the text of the 2017 OPSC supports either answer (1) or (2) in the interpretation. As far as I can see, they just invented those requirements without any supporting legislative text.

    So the upshot is that to comply with the interpretation, use a horizontal wye with a street LT90 to connect the WC to the wet vent. That will be your option with the least offset. [Were it not for part (2) of the interpretation, you could use a wye rolled up 45 degree from horizontal with a street 60, that would give you less offset.]

    Cheers, Wayne
     
  14. Jeff H Young

    Jeff H Young In the Trades

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    Yea how do you like that interpretation? only shared because its not clear to me that Oregon would allow combi on back for a w/c . In a case like this I would consider asking inspector and if not being inspected I'd feel comfortable either way that it was a workmanlike install
     
  15. Michael Young

    Michael Young In the Trades

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    Sep 20, 2016
    Location:
    North Carolina

    Looks like A is wet vented from the lavatory
    Looks like B will need its own dedicated vent
     
  16. wwhitney

    wwhitney Well-Known Member

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    Mar 17, 2019
    Location:
    Berkeley, CA
    Except neither the UPC (in force for the OP) or the IPC allow for horizontal wet venting on a laundry standpipe. Horizontal wet venting is limited to bathroom fixtures.

    Cheers, Wayne
     
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