Shower/Tub venting

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by TheGewp, Oct 6, 2019.

  1. TheGewp

    TheGewp Member

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    Can i vent a shower and a bathtub on the same 1.5" vent? I have a back to back shower/tub currently and i am remodeling the shower side. I am hoping i can combine the vents for each into one. Something like the image attached? Thanks!
     

    Attached Files:

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Almost, but not quite. Below that top connection, it's a drain and can't be used as a vent. But, if you bring a vent up from the lower one, you can then attach it to the vent above so you don't need to run two vent lines all the way up. Normally, you'd revent the line 42" above the floor, or 6" above the height of the highest drain (the 42" comes from a potential 36" counter plus the 6").
     
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  4. Reach4

    Reach4 Well-Known Member

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  5. TheGewp

    TheGewp Member

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    What if i used a double fixture tee instead of stacking them? Also, off topic, why are bathtubs usually shown with 1.5" pipe and showers with 2"? Can i use 2" on a tub? Thanks!!
     
  6. Reach4

    Reach4 Well-Known Member

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    A tub has some storage so if the drain goes slower, there is time to empty the tub. A shower would overflow quickly.

    Yes, you can use 2 on a tub.
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    There may be a smaller selection of drains in 2" than 1.5", but they're available.
     
  8. TheGewp

    TheGewp Member

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    Makes sense. How about using a tee in the image i attached?
     
  9. Reach4

    Reach4 Well-Known Member

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    I think you could use a double santee, but better would be that double fixture fitting that you mentioned. Use a 2x2x2x2 and reduce for the tub somewhere along the line... maybe at the trap, or even at the double fixture fitting.

    What I am not sure of is whether there is a problem with your original drawing with two santees.
     
    Last edited: Oct 8, 2019
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Note that the trap arm cannot go down (beyond the nominal 1/4"/foot slope) until it is vented.
     
  11. TheGewp

    TheGewp Member

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    Basically i would like to do this: https://terrylove.com/images/double_lav_rough_2.jpg with a shower and a tub that are back to back. It is the only way to combine the vents without ripping a wall apart. I am trying to remove the shower vent to make room for a niche in the shower wall and avoid working around a floor joist. Can i use a 2x2x2x2 double fixture tee and size down to a 1.5" line for the tub and vent and leave it at 2" for the shower and drain to the stack? Thanks!
     
  12. TheGewp

    TheGewp Member

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    Just wonted to bump this thread. Can i use a 2" double fixture for a back to back shower and tub? Thanks!
     
  13. TheGewp

    TheGewp Member

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    Finally got to this, everything look OK? I will add straps when i get the floor supports in. The nearest 2" nub will go to a shower. Thanks!

    2020-01-26 19.13.09.jpg
     
  14. plumber01

    plumber01 In the Trades

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    Too many turns in the trap arm. Cant exceed 90 degrees without a cleanout on a trap arm with 2" pipe or less.

    Looks like you could have configured the double fixture tee better to avoid that.
     
  15. TheGewp

    TheGewp Member

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    So replacing this 90 with a combi with a clean out cap should do the trick?

    2020-01-26 19.13.09_2.jpg

    The shower drain would need 2 90's if i rotated the tee 90 degrees, is there a better way other than that? Thanks!
     
  16. James Henry

    James Henry In the Trades

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    You could have stacked your fixtures like you had in your original drawing. Either way code says you need a 2" drain.
     
    Last edited: Jan 27, 2020
  17. TheGewp

    TheGewp Member

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    The tee and below is 2". The vent and the drain/trap arm currently connected is 1.5 from a bathtub.

    So if i CAN stack them like in my "drawing", both santees need to be 2"? Does it matter if the shower or the tub is on top? Thanks!
     
  18. James Henry

    James Henry In the Trades

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    Both San-tees need to be 2" because one is a vent for the other. if you want super fast drains use 2" p-traps and drains on both. I would put the shower on top. What you have is a common vent / vertical wet vent. Perfectly legal.
     
  19. TheGewp

    TheGewp Member

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    Finally got to it. Used a T-Waste drain on the tub and it can now handle the full flow from the faucet.

    2020-02-12 18.14.49-1.jpg
     
  20. James Henry

    James Henry In the Trades

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    good to go.
     
    TheGewp likes this.
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