In California Bay Area city of Santa Rosa. I've got a job where i have a foreman telling me i can't roll my combo for venting at a 22.5, only a 45. I always read the code as as long as i'm above the centerline of the waste pipe i'm rolling off of i'm fine. There is a generic picture showing 45 degrees as an example but i think a 22.5 is fine.

How do you guys interpret the code on this. First pic is of the illustration of the code, followed by an example of rolling off at a 22.5 with a sixteenth showing where the vent take off is in relation to centerline of waste.

Picture from codebook

[ibb.co]







Picture showing vent take off at a 22.5 with sixteenth bend over centerline of waste pipe.

[ibb.co]



Edited 2 times.

A 22.5 i

What "I" think matters not - what the INSPECTOR thinks, however, ...................



ASK the local AHJ.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Not a pro but perhaps it is not so much that rolling angle but there are only some angles that are practical to roll up and get back to horizontal. For a combo, a 22.5 degree roll up will need a 22.5 degree elbow to bring it back to horizontal. I wonder if the contractor is thinking about a wye transition. For a wye, if you roll it up 45 degrees, you can use a 60 degree elbow and it will return the outlet side to horizontal and at the same time complete a 90 degree turn. If you roll it 22.5 degrees you will need more than multiple fittings to bring that to horizontal and a 90 turn.

2019 Ca Plbg Code -


Where did that 22.5* picture come from? The bottom of the vent opening into the horizontal drain needs to be at/above the horizontal centerline. This is also stated in the 45* drawing.

I drew it in revit to illustrate that i could roll the combo at a 22.5 with a sixteenth bend and have the invert of the vent pipe be above the centerline of the waste line.

... the key words are " taken off "


the 'take off' fitting must be above the centerline ... IMO

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

even if allowing for the pipe wall thickness it is STILL below



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

You would need to have a "by the book" inspector to have a problem with it.

? why would one not want a 'by the book' inspection to enforce the MINIMUM standards ?

remember: the code is the MINIMUM, not necessarilly good or best practice




SHEEZ ..... he we go again ..... thank the creator i was always an employee who could, and often did, quit

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Rolling on a 22 1/2 fulfils the spirit of the code, and I never had an inspector turn it down.

Interesting discussion, I am trying to understand this requirement of the vent invert being above the centerline. I think I understand the intent, but I do not understand the part about using an angle (in this case 45 degrees) to make this determination.

If you want to be technical about it, a 4" wye with a 1.5" branch is going to need a smaller roll up angle to get the invert to clear the centerline when compared to a 4" wye with a 4" branch because a smaller branch starts with a higher invert. So to actually follow this requirement exactly, wouldn't they need a different minimal angle for 4x4x4 vs 4x4x3 vs 4x4x2 vs 4x4x1.5, the same for 3", 2", 1.5"?

yep


hence, for simplicity in rule making, 45 is the best compromise

OR

you MAY simply and PROVABLY be ABOVE THE CENTERLINE

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

such is the problem with dry venting.
this is why wet venting is my prefered method. the vent is washed everytime the wet vented fixture is used. Z

AND if the vent ever becomes blocked you will know as that wet vented fixture will not drain.