# Back to back WC code



## yoyoer (Nov 28, 2012)

Howdy folks,

Its been a while since I have been on here. I am a Journeyman Plumber / Gas Fitter but please bare with me my 6 years of experience is really in service of commercial heating systems.

I am doing a residential bathroom reno for a friend. He is splitting one over sized bathroom into two. My question is for connection of back to back water closets is it ok for me to use a double Y fitting. In our code in BC it states I cannot used a double sanitary T fitting on the horizontal but a double Y fitting should be correct? does the same goes for the showers? Ill wet vent the whole thing through the two back to back basins. 

I suppose the other way I could do it would be to run a 4" main and then have individual branches for each fixture.

Let me know if I am on the right track thank you all.


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## Tommy plumber (Feb 19, 2010)

First things first. We politely request an introduction from newbees. Oh, and post it in the intro section.


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## yoyoer (Nov 28, 2012)

Ok iv completed that introduction !


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## OldSchool (Jan 30, 2010)

Double y only on vertical under our code here ...... No double Ty on drainage


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## yoyoer (Nov 28, 2012)

Right, can I use a double y and 1/8 bend on the horizontal?


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## U666A (Dec 11, 2010)

yoyoer said:


> Right, can I use a double y and 1/8 bend on the horizontal?


Double wye can't be on horiz. Period. That's Obc though.

Can't achieve slope on all 3 branches, according to local inspectors.


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## OldSchool (Jan 30, 2010)

U666A said:


> Double wye can't be on horiz. Period. That's Obc though.
> 
> Can't achieve slope on all 3 branches, according to local inspectors.


That not true ... In Texas .... Those guys swear by horizontal double Y


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## U666A (Dec 11, 2010)

OldSchool said:


> That not true ... In Texas .... Those guys swear by horizontal double Y


I was duped into watching a video the other day that showcased a member of the armed forces proclaiming that there are no illegal aliens in Texas...

I rest my case.

Darn it Tex, don't make me post the sticker again! :jester:


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## OldSchool (Jan 30, 2010)

U666A said:


> I was duped into watching a video the other day that showcased a member of the armed forces proclaiming that there are no illegal aliens in Texas...
> 
> I rest my case.
> 
> Darn it Tex, don't make me post the sticker again! :jester:


Isn't area 51 in Texas ???


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## U666A (Dec 11, 2010)

OldSchool said:


> Isn't area 51 in Texas ???


Texas... New Mexico... Same dif'right? :jester:

I think I'm gonna get it for that one... :laughing:


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## OldSchool (Jan 30, 2010)

U666A said:


> Texas... New Mexico... Same dif'right? :jester:
> 
> I think I'm gonna get it for that one... :laughing:


I though Texas was the new Mexico .... Thats what they are all saying ... More mexicans than texans


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## U666A (Dec 11, 2010)

OldSchool said:


> I though Texas was the new Mexico .... Thats what they are all saying ... More mexicans than texans


You'd better edit that and add a "lol"... :laughing:

(insert joke about queers and steers)


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## yoyoer (Nov 28, 2012)

Humm, Says this in my code

Wet venting
Where two water closets are installed, they are connected at the same level by means of a double sanitary T fitting if the vent pipe is vertical and by means of a double y fitting if the vent pipe is horizontal

But then it also says....
A double sanitary T fittings shall not be used to connect the trap arms of a back outlet water closets installed back to back--- I guess this means flush valve type

Ugh why can't my multi meter solve this problem

So I'll throw some 45s on a double y and call it good


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## U666A (Dec 11, 2010)

I dunno where my codebook is, but I think I remember something about having to use a dual waste fitting below 3", but a double santee could be used on 3"... Os? Mark?

I'm sure you're not using rear outlet w/c's?


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## U666A (Dec 11, 2010)

Wait a minute, you're not thinking of using a double santee on the horizontal are you?!? :no:


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## OldSchool (Jan 30, 2010)

U666A said:


> I dunno where my codebook is, but I think I remember something about having to use a dual waste fitting below 3", but a double santee could be used on 3"... Os? Mark?
> 
> I'm sure you're not using rear outlet w/c's?


Hey if his code book says that ... Then why is he even asking ...

I know our code does not allow it and I am on the same page as U666A

Go ahead stick a ty in there ... Then some day run a snake through one of the drains and the snake will go right up the other toilet and crack it in two ...

I know because I broke a few toilets like that ...


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## ironandfire (Oct 9, 2008)

American Standard recommends a vertical double combo on their back to back installs.

http://www.americanstandard-us.com/assets/documents/amstd/install/Install_1558.pdf


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## AKdaplumba (Jan 12, 2010)

U666A said:


> Double wye can't be on horiz. Period. That's Obc though.
> 
> Can't achieve slope on all 3 branches, according to local inspectors.



So what do you use then? cant use a cross tee.


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## OldSchool (Jan 30, 2010)

AKdaplumba said:


> So what do you use then? cant use a cross tee.


Two Y's


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## U666A (Dec 11, 2010)

Nevermind...


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## U666A (Dec 11, 2010)

If I recall, 2010 npc allows for a double wye on its side... Not in On though.


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