Horizontal wet vent mock up, Please advise.

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by martha bartley, Feb 1, 2020.

  1. martha bartley

    martha bartley New Member

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    Jan 16, 2020
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    Oregon
    I will be ripping out my previous attempt at this. Here is the mock up for my new plan. I will be doing a horizontal wet vent for the bathroom group and kitchen sink. I would appreciate feedback from the pros. (I promise if you help me through this I will never attempt this on my own again.)
    Attached are two views. Thanks
    7870B063-5054-467E-A8C6-D4FF3EF0DFCB.jpeg 685017AE-A32A-4A5A-A398-3BA9B29A57AF.jpeg
     
  2. James Henry

    James Henry In the Trades

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    Plumbers can't design a plumbing system without knowing where the walls are. draw a floor plan with fixture locations and wall locations.
     
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  4. martha bartley

    martha bartley New Member

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    Of course, I’m sorry. Do you need the measurements? Here is a representation of the room with my proposed plan. 34119568-34DB-4A1F-8930-D38C4D6638B5.jpeg
     
  5. Reach4

    Reach4 Well-Known Member

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    Your mockup seems to put the closet flange very high or your piping very deep.

    I suspect you don't need the cleanout shown at the toilet, since the toilet could be removed.

    You will put an AAV in the attic, rather than tying into vent lines in the attic?
     
  6. martha bartley

    martha bartley New Member

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    The pipes are indeed low on that side because the soil pipe goes under the exterior wall’s skirting. The horizontal pipe under the toilet will end up being buried.

    As for the AAV here is why I’m kind of stuck with that. I hired a plumber to cut the cast iron vent stack so I could tie into it without disturbing the section that goes through the roof. He said there was no way to secure the straight pipe in the attic, so he cut it in the wall under the bell/hub so there would be a way to clamp it and hold it up. Made sense at the time, but now that leaves me with no way to tie the vent on the opposite wall to the CI pipe in the attic. I am hoping the AAV is sufficient, but if you all say it’s not, I will need to take out the section of CI that extends through the roof so I can connect the two together.

    Overall I tried to hit all of the points I have seen you all address in other threads, and what I understand the code to read but I am still questioning my understanding of them, so please tell me if I got any of it wrong.
    #1 the dry vent stack comes in after the first fixture so the entire horizontal line is wet?
    #2 The lavatory can connect to the toilet drain? This one Im a little fuzzy on especially on what fitting to use, so I would appreciate advice on that connection. Can it be done, and if so did I use the correct fitting?
    #3 I’ve seen many posts saying the toilet is always last, but florida code says for horizontal wet vents any fixture not part of the bathroom group must go downstream of the group. (section of code attached). I may be misreading that so again appreciate your feedback.

    Thanks for your time helping me with this.
     

    Attached Files:

  7. James Henry

    James Henry In the Trades

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    I'm not following your vent situation. is there a vent currently going through the roof where you want to tie the shower into? is the proposed lav vent / AAV the one that the plumber cut off? BTW, it would have been very easy to secure the vent pipe in the attic. He was probably afraid of causing a roof leak.
     
  8. martha bartley

    martha bartley New Member

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    So in the picture of the room, the black dot on the interior wall is the existing vent stack that goes through the roof. At the moment it is just a piece that comes through the attic and about 8” down into the wall. I need to connect that with the soil drain that exits on the opposite side of the room.
    Since it’s under the floor, my understanding was that it would be called a horizontal wet vent and the fixtures would need to intercept it in a way that the entire length was wet. Therefore, if I tie the tub into the stack after the vertical vent it would cause a portion of of the H wet vent to be dry, which I thought was illegal under the house. This is why I did the convoluted connection of the tub to the drain. Example of what I was trying to avoid. Am I wrong about this?
    22EB18D4-95FC-43AC-9910-570C9A9F4753.jpeg
     
  9. martha bartley

    martha bartley New Member

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    He was and I am worried about causing a leak. Having said that I would prefer to join the vents in the attic. Here is a photo of the 4” pipe in the attic. The good news is there’s plenty of space to work since it’s in an interior wall. Would you explain how I could secure that pipe if I cut it off up there? I think that would be the better way to go.
    E733C91A-12F7-46AC-890B-FA890529A0AF.jpeg
     
    Last edited: Feb 2, 2020
  10. James Henry

    James Henry In the Trades

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    It's kinda hard to come up with a good drainage layout with your vent situation. My advice would be to find someone competent to secure and cut your existing vent that goes through the roof and tie you lavatory vent into that vent. I sketched a typical horizontal wet vet diagram that would pass if your lav was properly vented. " STUDOR VENTS" claims you can wet vent a bathroom group with an AAV but that will have to be approved by your plumbing inspector. I just saw the picture of your attic vent. that can easily be braced and cut.


    https://ipscorp.com/pdf/studor/Studor_Technical_Manual.pdf
     

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  11. martha bartley

    martha bartley New Member

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    Okay I think I understand. Are you saying if I connect the vent stack at the lavatory to the roof that’s all I need and I can eliminate the one currently in the interior wall by the tub? That is making sense.
     
  12. James Henry

    James Henry In the Trades

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    Location:
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    Use a sawzall with a blade made for cast iron and go slow. its doable it just takes some effort.
     

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  13. martha bartley

    martha bartley New Member

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    I didn’t know the riser clamp existed. That looks very doable. Thank you for the great sketch.
     
  14. gagecalman

    gagecalman Member

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  15. martha bartley

    martha bartley New Member

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