Vents: When and where?

[PrecisionPlum]

Vents:
My boss always says he just knows what is needed. I have been working in plumbing for less then a year and I am having a difficult time understanding what is needed when.

We are only going to add fixtures on the first level, and the second floor and kitchen are already in place. I want to know how to do it, not just be told what to do.

I made up a layout of a rehab job I think we are going to do. If I am starting to get this then I don't think we are going to need any additional vents then what is shown here because it is a combination of a wast and vent system, and the developed horizontal lengths from the fixture to the house drain is less then 5' or less.

Am I right???

NOTE: It is not shown in the drawing, but the lav would wye in after the WC

 

[voletl]

Every fixture needs a vent

Looking at the picture you posted nothing has a vent

 

[Matt30]

Looks like you need a new boss

 

[Mr_David]

What code are you using?
Maybe we can help point to the right place in code so you will understand.

 

[PrecisionPlum]

Thank you for your feedback Mr_ David. It is very much appreciated.
Please see my revised post. Because of wall space, I think the 3" cross
Tee is a stretch, and that one CW needs to sit above the other. Also,
the Kitchen is on a under counter AAV. I look forward to your comments.

The code is IPC.

 

[phishfood]

Under IPC, you would need to tie that second water closet into the vented branch with the other water closet, not into the main line. Depending on what kind of fixture it is, that sanitary cross might not be allowed, and no matter what kind of fixture, it is a bad idea.

AAV's are in general a bad idea, but if you are not able to get into the second floor to revent, you might not have much choice.

 

[PrecisionPlum]

Phishfood,

Thank you for your input. The comments I receive are very helpful in developing a better understanding of vents and drains, and I am determined to get a handle on this. Please look at the revised layout.

The WC: Can't it just go into the drain.? Doesn't the drain act as a horizontal wet vent?

The sanitary cross: the ACW connections could easily be stacked.

 

[Matt30]

I'm in Canada, but most things I've saw from this IPC code are whack! I apologize and retract my rude comment.

 

[phishfood]

Check out Chapter 9, section 912, Wet Venting. Basically, it states that any fixtures outside of the 2 bathroom groups allowed by that code section have to discharge downstream of the bathroom group(s).

 

[PrecisionPlum]

Revised drawing:

Phishfood,

Thank you for your suggestion. I did see this section. The downstream end of the drain is "below" the left 2nd Fl. bathroom group; however, at the upstream end is also a soil stack, and that makes the drain under the slab a non-compliant horizontal wet vent. I did revise the drawing and added more information for clarity, though I am not sure if the first floor WCs are vented properly.