# Why is this venting not permitted?



## Michael.L (May 15, 2019)

I was told that my hand sink drain cannot be used to vent the mop sink because this is not part of a bathroom group. What I don't understand is, why does this not comply with Section 911 of the IPC?

*IPC 911.3 Connection at different levels.*
Where the _fixture drains_ connect at different levels, the vent shall connect as a vertical extension of the vertical drain. The vertical drain pipe connecting the two _fixture drains_ shall be considered to be the vent for the lower _fixture drain_, and shall be sized in accordance with Table 911.3. The upper fixture shall not be a water closet.​
Could someone please explain why this plumbing does not meet code?


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## cda (May 15, 2019)

Not into pipe

Guess your set up is on same floor

And sized right??


https://www.kelso.gov/sites/default/files/images/cd-documents/plumbing_venting_brochure_2018.pdf


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## jeffc (May 15, 2019)

“Everyone does it this way.” That is just your standard vertical wet vent that has been used and legal for years. I wonder if the horizontal wet vent provisions are being inappropriately applied to this situation.


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## Michael.L (May 15, 2019)

cda said:


> Guess your set up is on same floor
> And sized right??


Only one floor in the building, so everything is on the same floor level. Pipe sizing is correct, as far I'm aware. I was told the issue is that the mop sink is venting through the wet discharge pipe of the hand sink. But it seems that should be acceptable according to IPC 911.3.

I'm just trying to understand the code.


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## Michael.L (May 15, 2019)

jeffc said:


> “Everyone does it this way.” That is just your standard vertical wet vent that has been used and legal for years. I wonder if the horizontal wet vent provisions are being inappropriately applied to this situation.


I think some confusion may come from IPC Section 912 on Wet Venting:

*912.1.1 Vertical wet vent permitted.*
Any combination of fixtures within two _bathroom groups_ located on the same floor level is permitted to be vented by a vertical wet vent. The vertical wet vent shall be considered to be the vent for the fixtures and shall extend from the connection of the dry vent down to the lowest _fixture drain_ connection. Each wet-vented fixture shall connect independently to the vertical wet vent. Water closet drains shall connect at the same elevation. Other _fixture drains_ shall connect above or at the same elevation as the water closet _fixture drains_. The dry-vent connection to the vertical wet vent shall be an individual or common vent serving one or two fixtures.​
Since this section addresses wet venting specifically for "within two _bathroom groups_" it may be that people are interpreting that (correctly or incorrectly) as excluding all wet vents for similar fixture configurations not contained within a _bathroom group_. But if wet venting is only permitted within _bathroom groups_, then how is that limitation reconciled with the Common Venting stipulated in IPC 911.3?


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## Keystone (May 15, 2019)

What Code section did the inspector cite.


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## cda (May 15, 2019)

Michael.L said:


> View attachment 4394
> 
> 
> I was told that my hand sink drain cannot be used to vent the mop sink because this is not part of a bathroom group. What I don't understand is, why does this not comply with Section 911 of the IPC?
> ...





Did the person saying it is wrong,,,

Cite the code section that they say is in violation ????


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## conarb (May 15, 2019)

It may be because I'm in California, which is UPC and not IPC based, but as far as I recall wet-venting has always been illegal.


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## cda (May 15, 2019)

Is the definition the reason it is not allowed::::::


BATHROOM GROUP. A group of fixtures consisting of a water closet, lavatory, bathtub or shower, including or excluding a bidet, an emergency floor drain or both. Such fixtures are located together on the same floor level.


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## Michael.L (May 15, 2019)

Keystone said:


> What Code section did the inspector cite.


This has not yet been built nor inspected. I'm planning the layout and want to ensure everything will "work" and be code compliant. I posted this configuration on a plumbing forum and was told it would not pass inspection; no codes were cited by the two plumbers who said it wouldn't pass.

When I asked about IPC 911.3, one of the plumbers stated that he operates under UPC and that it might pass under IPC (which is the plumbing code adopted by my jurisdiction); he didn't know for sure. I'm hoping I may get a more authoritative answer on the code requirements here than on the plumbing forum.


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## Michael.L (May 15, 2019)

conarb said:


> It may be because I'm in California, which is UPC and not IPC based, but as far as I recall wet-venting has always been illegal.


My jurisdiction has adopted IPC, not UPC. That said, based on my reading of the 2018 UPC, wet venting is permitted. Furthermore, there is no mention of bathroom groups in the UPC section on vertical wet venting.

*UPC 908.0 Wet Venting
908.1 Vertical Wet Venting.* Wet venting is limited to vertical drainage piping receiving the discharge from the trap arm of one and two fixture unit fixtures that also serves as a vent not exceeding four fixtures. Wet-vented fixtures shall be within the same story; provided, further, that fixtures with a continuous vent discharging into a wet vent shall be within the same story as the wet-vented fixtures. No wet vent shall exceed 6 feet (1829 mm) in developed length.


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## Michael.L (May 16, 2019)

cda said:


> https://www.kelso.gov/sites/default/files/images/cd-documents/plumbing_venting_brochure_2018.pdf


I'm looking at the last diagram on page 10 of this document, published by the ICC, and it appears to me that it's exactly what I'm doing.


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## cda (May 16, 2019)

Maybe call the locals and either email your diagram or go by and ask the question


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## Michael.L (May 16, 2019)

cda said:


> Maybe call the locals and either email your diagram or go by and ask the question


I had previously emailed the local Building Dept official to request a preliminary meeting to discuss some issues regarding the build-out. He replied that they are too small an office to meet in advance and that I should simply submit my TI building application.


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## Michael.L (May 16, 2019)

Michael.L said:


> I'm looking at the last diagram on page 10 of this document, published by the ICC, and it appears to me that it's exactly what I'm doing.


Here is the diagram from the ICC's publication on venting:



Again, there is no discussion in *IPC Section 911* that states Common Venting is restricted only to _bathroom groups_.


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## cda (May 16, 2019)

Michael.L said:


> Here is the diagram from the ICC's publication on venting:
> 
> View attachment 4395
> 
> Again, there is no discussion in *IPC Section 911* that states Common Venting is restricted only to _bathroom groups_.




Submit it

Cite the code section on the plans, so it shows you researched it and cited sections to support your design 

Do not understand why the bo can’t give you fifteen minutes 

To me it saves him time down the line

Or maybe he is to busy to even notice the vent set up, when you submit!!!!!!


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## HForester (May 17, 2019)

The arrangement is compliant with the IPC (and IRC)  "common vent" section.   Although it is not termed a "wet vent" system it is a very simple wet vent for the lower fixture.

I don't know about the UPC...it is getting too hard to decipher that language.


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## Michael.L (May 17, 2019)

HForester said:


> Although it is not termed a "wet vent" system it is a very simple wet vent for the lower fixture.


From my reading of the IPC (and UPC), I'm not sure how one distinguishes a "simple wet vent" from a "wet vent system." There really needs to be greater clarity in the code. Particularly in the IPC & UPC sections on Wet Venting.


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## HForester (May 19, 2019)

Michael.L said:


> From my reading of the IPC (and UPC), I'm not sure how one distinguishes a "simple wet vent" from a "wet vent system." There really needs to be greater clarity in the code. Particularly in the IPC & UPC sections on Wet Venting.



All I am saying that is that a common vent (connecting at two different levels) is _like_ a simple vertical wet vent...the flow from upper fixture passes through the same pipe as the venting air for the lower fixture.   In your arrangement, you call it a common vent as it meets all the rules for a common vent.


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## Mech (May 20, 2019)

At a quick glance, you might be able to call this a waste stack vent (Section 913 in the '18 IPC) provided the pipe sizing is correct.


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## cda (May 21, 2019)

This help any::;


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## HForester (May 21, 2019)

Yep, same thing.


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## ADAguy (May 21, 2019)

Key appears to be their use of the term Bathroom, vs there being an adjacent janitors closet?
And if the sink was in a kitchen on the other side of the wall that wouldn't be ok?


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## HForester (May 22, 2019)

Drainage plumbing doesn't care about internal walls....


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## Mech (May 22, 2019)

They are most likely looking at the probability of all items from two bathroom groups operating simultaneously, not the physical location of the fixtures.


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