IPC Vent Grade

Is the interpretation of the IPC code saying that A and B are acceptable?
Where as the UPC clearly states only B is allowed

 

I vent up from the fixture being served Picture B

Picture A I would not find acceptable

 

Thanks for the answer
I do not find picture A as acceptable either,
BUT, am being told by IPC plumbers [I am a upc plumber]
that the grade back to the fixture does not matter
in this diagram, this would not be acceptable.[upc] i would sleeve that duct in a heat beat. lol

 

Frodo, your interpretation makes sense to me. I could see why IPC would logically find either OK. I am not a plumber.

What was the "i would sleeve that duct..." part? Accidental paste?

 

Terry... I know what you have always done, same as me, drain back to the fixture it serves
What I am looking for is the precise interpretation to the IPC vent grade definition.
the way it is worded, You can install a vent any way you want, as long as it has fall.

The IPC plumbers i am running into are saying that "AIR DONT CARE"
which is technically true, it just makes the work look like total ass

 

It sounds like the plumbers you are running into have air in their heads. Air actually does care. Warm air rises. Without the slope to the fixture gasses might get trapped. Logically you also plan for the possibility of rainwater and condensation. Does any other liquid get in a dry vent above flood level?

If the grade slopes down to the vent then you are using the vent as a drain. It will work but not code in most situations.

Note your sag in red would act as a trap. So if you tested the system by filling with water you would have issues starting on day 1.

 

I think the logic is that with A, the only water heading toward the vent is vent water... which would only be condensation. Just as with the rain and other condensation, the vent water eventually hits a drain.