Pipe Venting Questions

[PlumbingDIYer]

Hello,
I am hoping someone can help me understand some comments and make corrections. I am trying to add a bathroom and sink directly above my downstairs bathroom and sink. I have never drawn plumbing for more than one floor before. I got the following comments back from the city for the isometric drawing attached:

1. Water closet improperly vented,
   
2. dry vent shown horizontal below flood rims of fixture and shown tied together too low.
3. show proper direction of flow for the drain.

Can someone help me understand and correct?

Thanks in advance

 

[PlumbingDIYer]

I think I understand number 2 so I cleaned it up (changes attached). The one I am having the most trouble understanding is #1 from above. I do not understand why the water closets (toilets) are improperly vented.

 

[Sponsor]

 

[wwhitney]

What plumbing code are you subject to? It varies across states.

As to (1), at present the lower WC is only vented via the 4" stack. Depending on the plumbing code, that may not be allowed. The conventional dry vent approach would be to pull a 2" vent off the lower WC fixture drain before it hits the stack and run that up parallel to the stack to 6" above the upper WC flood rim level before reconnecting it. But under some circumstances, I believe the IPC allows the WC arrangement you show, it would bear more research.

As to (2), I think someone assumed that the drawing is to scale and judged that the two horizontal jogs circled in red on the right are too low. It would be enough to raise those jogs up higher in the diagram, possibly with a note saying "minimum 6" above sink flood rim".

As to (3), that's a bit of a puzzle to me. The only thing I can think of is that you show several nodes in your drawing where it is unclear what fitting you would use. So you could circle the node and add a note about the fitting, or draw in more local detail that makes it clear: In a couple places you show a node with three pipes exiting at pair-wise right angles; that fitting doesn't exist, so you might clarify that by separating it into two nodes. Likewise, where you have a combo, instead of drawing that as a tee intersection, you can draw in an explicit wye, i.e. the side line coming into the tee gets a little 45 degree bend just before the intersection.

Cheers, Wayne

 

[PlumbingDIYer]

Hi Wayne,

Thank you for the quick response. The drawings are subject to IPC 2018 with Georgia Amendments (2020).

(1) I figured the venting used for the water closets fit under the "single stack vent system" of IPC 917.1-917.9 but either it does not or the reviewer is not comfortable with it. I changed the venting the match the conventional method you mentioned. The first flow is now vented via a 2" pipe prior to the stack and connected a minimum of 6" above the second floor flood rim level. See attached.

(2) I changed them and will add a message to the reviewer that I adjusted the drawing so that it does not appear even close to horizontal. See attached.

(3) Thanks for the suggestion. I changed the fittings so that it is clear they are wyes and elbows. I also added a label to point to the direction of water flow. See attached.

Thanks for your help.

 

[wwhitney]

(1) I figured the venting used for the water closets fit under the "single stack vent system" of IPC 917.1-917.9 but either it does not or the reviewer is not comfortable with it.

Or the reviewer is not familiar with it, as it is a pretty complicated section. At first reading, it does appear your original layout would qualify, but I'd have to double check to be sure. So if you have confidence the layout does comply, you could respond to the reviewer with a note to that effect and a reference to the IPC section.

Cheers, Wayne

 

[PlumbingDIYer]

Hi Wayne,
Thanks for your advice again. You have been a great help to me as I tried to understand how the reviewer may be viewing the drawings. After reading that section of the IPC, it seems like it should work but I am more familiar with electricity so I will give the reviewer the benefit of the doubt. I have already changed the drawings and will submit them with the conventional venting.

Thanks again.