# wet vent for two toilets



## amakarevic (Apr 12, 2007)

my powder room is on the 1st floor directly beneath the 2nd floor bathroom. there is a 4" vent stack running by. i was gonna have the powder room toiled wet vent off of the same stack. i believe this is doable albeit not ideal. was gonna hear opinions. i was thinking of using 4x4x3 Ts for both toilets off of the stack.

the reason i think this is doable is because i think that's how it's done in office and school building rest rooms that are in the same floor position on every floor and toilets are right above one another so i am assuming they are using the same concept.

correct me if wrong. but at this time, i have little in terms of alternative how to do it.

thanks


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## TheEplumber (Jul 20, 2010)

I'm not quite following your proposal, but you can't wet vent 2 floors (at least the UPC doesn't allow it)
multiple floors can share a common waste stack or a common vent stack though


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## amakarevic (Apr 12, 2007)

it's quite simple: one vent stack, from the roof to the 2nd floor is just vent, then the toilet on the 2nd floor, then the section between the 2nd and 1st floors acts as both vent AND drain (for the 2nd floor toilet), then the 1st floor toilet ties in, which is what i am concerned about. can the 1st floor toilet vent OK if the portion of the stack between it and the 2nd floor toilet is also used as the drain for the 2nd floor toilet?

the two toilets are right above one another and use one vent stack.


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## the_man (Aug 14, 2010)

what EPlumber is saying, is that you cannot wet vent between 2 floors according to the UPC. You can run separate waste stack and vent stack, or vent the lower toilet separately. Also, according to the UPC code, you cannot wet vent anything other than 1 and 2 unit traps (sinks, tubs, and showers basically), and any wet venting must be done within 6 feet of the lowest fixture.


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## amakarevic (Apr 12, 2007)

i have a similar setup between the 1st floor and the basement now and it works fine.


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## amakarevic (Apr 12, 2007)

the only time this COULD be an issue is if the two toilets were being flushed at the same exact time but even then the "brown" from the 1st floor would just wait until the 2nd floor brown goes down and frees up the pipe for venting. i don't care about UPC, only practical matters. the code is often far more strict than what works in practice. i am not getting this inspected.


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## the_man (Aug 14, 2010)

not saying that it wouldn't work, just saying what the AHJ says about it (at least around me). where are you at? some codes may allow it, others can probably chime in about that. the only time you would have issues with it is when both toilets are flushed at the same time


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## amakarevic (Apr 12, 2007)

i supposed we typed our responses simultaneously  and arrived to the same conclusion about the problem being only in case of simultaneous flushing.

i am in mid-Atlantic USA, i don't wanna specify the exact municipality cause i'm doing this without permits and am afraid of the big brother from the county office watching this forum to catch ppl like me.


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## TheEplumber (Jul 20, 2010)

amakarevic said:


> i have a similar setup between the 1st floor and the basement now and it works fine.


Then why do you bring up the question?
IMO- multi floor WC's should not be wet vented on the same drain


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## DannyT (Mar 23, 2011)

like everyone said, the second floor toilet should have its own vent according to code. being that it is a 4 inch vent it would probably work fine but wouldn't be according to code. i have seen people plumb bathrooms with no vent at all. it's your house.


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## Anti-wingnut (Oct 18, 2009)

TheEplumber said:


> Then why do you bring up the question?
> IMO- multi floor WC's should not be wet vented on the same drain


That's how people do things around here. They have a preconcieved idea, and ask if it's alright to do so. Since they have already made up their minds, and they don't recieve the answer they wish, then it's time to debate the subject.


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## royaldjs (Jun 22, 2014)

I was hoping to do the same with a second floor bathroom / shower. I was going to use a 'Y' at the stack for a second floor toilet (connected to a horizontal run) that carries on to collect a shower and then goes up through the roof for a vent. Can you show a diagram how to vent all this correctly? Do I need to run a separate vent for the first floor toilet (that has a vanity on a 'Y' just above it)... and where would the vent for the first floor connect?


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## ben's plumbing (Oct 6, 2011)

your question was answered correctly by e plumber... how you chose to proceed is entirely up to you.....just know what you are doing is wrong...and no permits or inspections.....really.....


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## Ghostmaker (Mar 2, 2013)

Not legal under IPC. Not a waste stack vent because toilets are a prohibited fixture.

If he resides in Philadelphia it may be legal.

By the way a drain is not a vent. A wet vent is limited to a single floor period.


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## Ghostmaker (Mar 2, 2013)

amakarevic said:


> i supposed we typed our responses simultaneously  and arrived to the same conclusion about the problem being only in case of simultaneous flushing.
> 
> i am in mid-Atlantic USA, i don't wanna specify the exact municipality cause i'm doing this without permits and am afraid of the big brother from the county office watching this forum to catch ppl like me.



Should be real funny when a presale inspection knocks 20 grand off the value of your house.....


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## Millmo (Feb 27, 2021)

amakarevic said:


> i supposed we typed our responses simultaneously  and arrived to the same conclusion about the problem being only in case of simultaneous flushing.
> 
> i am in mid-Atlantic USA, i don't wanna specify the exact municipality cause i'm doing this without permits and am afraid of the big brother from the county office watching this forum to catch ppl like me.


So, how did this work out for you? I have the same scenario...

Any issues?


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