# Back to back toilets



## PlumbRob7 (Feb 7, 2011)

I can't find anything in the bc code about venting back outlet wc back to back...why can't you wet vent them??


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## U666A (Dec 11, 2010)

In Ontario, if they are symmetrically connected with a dual waste fitting and are the lowest fixtures, you can definitely wet vent them.
But I'm not supposed to tell you this until you post an introduction...


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## DIZ (Nov 17, 2010)

PlumbRob7 said:


> I can't find anything in the bc code about venting back outlet wc back to back...why can't you wet vent them??


do they have tanks?


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## plumber666 (Sep 19, 2010)

Obviously being back to back there's a wall between them. Why don't you circuit vent them? Although I often see a deer in the headlights look when I suggest this.


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## PlumbRob7 (Feb 7, 2011)

Where do I post an introduction....??? And they are symmetrically connected nominally horizontal nd I figured I'd wet vent thru the lavs but engineer wants a seperate vent out of the double sanitary tee.. It's a 10" pipe chase between block walls which was tight with 2" copper with 1" insulation for the flush valves nd the vent had to tie in with lav vent


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## greenscoutII (Aug 27, 2008)

PlumbRob7 said:


> Where do I post an introduction....??? And they are symmetrically connected nominally horizontal nd I figured I'd wet vent thru the lavs but engineer wants a seperate vent out of the double sanitary tee.. It's a 10" pipe chase between block walls which was tight with 2" copper with 1" insulation for the flush valves nd the vent had to tie in with lav vent


I'm not sure what your code says, but what you're describing would fly where I'm from. Why does he want a separate vent? I would think if you can demonstrate that it is legal in the code you are using, he would have to let it fly....

Oh, there is a section labled introductions. We get a lot of DIY trying to sneak in here, so guys will bust your balls a little bit if you don't post an intro. Don't take it personally.


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## plumber666 (Sep 19, 2010)

A little more info on the piping layout would help. How many w/c's are involved? Are the double tees in the horizontal position? Are the lavs in the same wall?


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## markb (Jun 11, 2009)

Engineer probably wants to make sure that during a future reno, if one carrier is disconnected, the lav rough-in does not have to be changed. 

Or he doesn't want to look at the carrier specs to see if you have space for your lav TY...to draw a separate drain is much easier.


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## 6th Density (Nov 29, 2010)

Here in Florida we have a code on it. 
FPC 706.3
"Installation of fittings. Fittings shall be installed to guide sewage and waste in the direction of flow. Change in direction shall be made by fittings installed in accordance with Table 706.3. Change in direction by combination fittings, side inlets, or increasers shall be installed in accordance with table 706.3 based on the pattern of flow created by the fitting. _Double sanitary tee patterns shall not receive the discharge of back-to-back water closets and fixtures or appliances with pumping action discharge.
Exception: Back-to-back water closets connections to double sanitary tees shall be permitted where the horizontal developed length between the outlet of the water closet and the connection to the double sanitary tee pattern is 18 inches (457mm) or greater."

_Now I don't know exactly what "pumping action discharge" means but if I'd have to guess it sounds like a force creating "positive" pressure on a system. So if the 2 toilets flush simultaneously they could potentially cause the vent to clog and...

Hope this helps:thumbsup:


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## lma1 (Feb 14, 2011)

PlumbRob7 said:


> I can't find anything in the bc code about venting back outlet wc back to back...why can't you wet vent them??


You *cannot* wet-vent back outlet WC installed b-t-b by virtue of Clause 7.5.4.2.2)a), 2006 BCPC. I believe this is the reason the Engineer wants you to dual-vent the 2 WC’s separately.


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## SlickRick (Sep 3, 2009)

lma1 said:


> You *cannot* wet-vent back outlet WC installed b-t-b by virtue of Clause 7.5.4.2.2)a), 2006 BCPC. I believe this is the reason the Engineer wants you to dual-vent the 2 WC’s separately.


 
How about an intro?

http://www.plumbingzone.com/f3/


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## lma1 (Feb 14, 2011)

lma1 said:


> You *cannot* wet-vent back outlet WC installed b-t-b by virtue of Clause 7.5.4.2.2)a), 2006 BCPC. I believe this is the reason the Engineer wants you to dual-vent the 2 WC’s separately.


I like to clarify because Clause 7.5.4.2.2)a) prohibits the use of a double sanitary T fitting in the situation you mentioned but Clause 7.5.2.1.1)c) mandates the use of such fitting, you therefore *cannot* wet-vent back outlet WC's installed b-t-b.


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## PlumbRob7 (Feb 7, 2011)

lma1 said:


> You *cannot* wet-vent back outlet WC installed b-t-b by virtue of Clause 7.5.4.2.2)a), 2006 BCPC. I believe this is the reason the Engineer wants you to dual-vent the 2 WC’s separately.
> 
> That section of the code you stated says sows that serve as wetvent do not require a vent stack. 75211c sow pipe may serve as wet vent provided where 2 wc are installed they are connected at the same level by means of dbl San tee if the vent is vertical and by dbl wye if vent is horizontal..
> This is the British Columbia plumbing code 2006
> ...


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## lma1 (Feb 14, 2011)

PlumbRob7 said:


> lma1 said:
> 
> 
> > You *cannot* wet-vent back outlet WC installed b-t-b by virtue of Clause 7.5.4.2.2)a), 2006 BCPC. I believe this is the reason the Engineer wants you to dual-vent the 2 WC’s separately.
> ...


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## PlumbRob7 (Feb 7, 2011)

lma1 said:


> PlumbRob7 said:
> 
> 
> > My apology. The correct clause that prohibits the use of a double sanitary T fitting in the situation you mentioned is 7.2.4.2.2)a) & not 7.5.4.2.2)a) as previously suggested.
> ...


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