# IPC and UPC Common Venting Violations



## Francis Vineyard (Jul 6, 2016)

Below are descriptive photographs taken from an illustrative book by Bob Scott; Plumbing Venting Decoding Chapter 9 of the IPC. This book was intended as a handbook to the 2015 IPC.  However I could not find the code sections in the IPC where these double bowl connections are in violation.  Do you know the sections they violate in the IPC or are they in the UPC?

Thanks in advance for your input.


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## north star (Jul 6, 2016)

*@ ~ @*

Francis,

*From the `06 UPC, Section  704.2:*
"Two fixtures set back-to-back, or side-by-side,
within the distance allowed between a trap and its
vent may be served by a single vertical drainage pipe
provided that each fixture wastes separately into an
approved double-fixture fitting having inlet openings
at the same level."

I do not know of the reasoning behind this Section ! 


*@ ~ @*


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## skipharper (Jul 8, 2016)

Interesting, common venting is typically associated with the attached photo and the fact that this person illustrates a correct and incorrect method under the sink is ridiculous to say the least. Whats the difference? The double pattern fitting is in most of the attached pictures. I wonder if that book tells one how to clean those traps that do not break apart-LMAO


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## steveray (Jul 8, 2016)

Maybe they are concerned with the "straight" pipe being full and siphoning the other trap?


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## Francis Vineyard (Jul 8, 2016)

2015 IPC (& IRC)


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## skipharper (Jul 8, 2016)

Is there a question Francis?


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## Keystone (Jul 8, 2016)

I'm thinking out load, throwing it out there. 

Could it be the traps as installed are hard piped, no ability to clean out?


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## Francis Vineyard (Jul 8, 2016)

Keystone provided an answer with his question; no cleanout required for nonremovable traps.


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## skipharper (Jul 12, 2016)

Sure enough!! I would love an intelligent answer as to why the Y fitting is no good but the double Y is


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## Paul Sweet (Jul 12, 2016)

Since this was supposed to be a handbook he should have cited the code violation.


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## HForester (Jul 24, 2016)

The Scott book is about VENTING.  The issue of the hard piped sink outlets thru the trap is not the point of the photo.
The violation is that when venting two traps on a horizontal common vent, a 'double pattern fitting" must be used according to the IPC Common Vent section (same in the IRC).

Coincidentally, the double pattern fitting provides for the required full size cleanout for the 2 inch drain...(but again, that's not forcing the double pattern fitting)

On the other issue of hard piped between the sink outlet and the double wye....there is nothing in the IPC and IRC that prohibits that practice. Cleanouts are required for horizontal drainage piping. The trap can be rodded through the sink strainer assembly. And maybe for a commercial establishment, this is not a bad practice as piping below sinks take a beating and joints would probably end up leaking (a lot.)


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## Joe Engel (Jan 22, 2019)

Lets resurrect this question again, if a Kitchen sink has one P-trap, no Wye is required. If two P-traps (typical with a double and G.Disposer), then Double Wye is needed not a single Wye, not for the drain but for the vent system per P3107 Common Vent...  Is this the correct code section?


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## HForester (Jan 23, 2019)

Section 3107.2.  It might be easy to first think about a vertical common vent with fixtures connecting at the same level. Now lay it down. What do you have to change? The double sanitary tee has to become a double wye. The vent can't be at the "top" (the cleanout end) of the double-wye because horizontal dry vent piping can't be below the flood level rim of the fixture. "The vent AT the connection" for a horizontal common vent arrangement is common for modern cast iron systems.  For no-hub, fittings EZS 13 and EZS 35 "vented tub wyes" .  There isn't an equivalent in PVC/ABS (that I know of) and I suspect, because of that, the vent was allowed to be downstream of the interconnection.   (I don;t wee an equivalent vented tub wye for hubbed cast iron but that needed fitting might have been a threaded Durham-type fitting in the old days as they didn't make hubbed cast iron in 2 inch...I think.)


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## steveray (Jan 23, 2019)

SECTION P3107
COMMON VENT
P3107.1 Individual vent as common vent. An individual
vent shall be permitted to vent two traps or trapped fixtures as
a common vent. The traps or trapped fixtures being common
vented shall be located on the same floor level.
P3107.2 Connection at the same level. Where the fixture
drains being common vented connect at the same level, the
vent connection shall be at the interconnection of the fixture
drains or downstream of the interconnection.


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