I'm probably in over my head but....

...am I on the right track?

Thank you in advance from hot, rural GA!

 

First of all, GA uses IPC, and not UPC code.

I suspect vents through the wall and not over the roof are not allowed. Yet you can use an AAV (air admittance valve) instead.

If you can route the laundry drain to not join other drainage until after the toilets, it will probably be simpler. How much flexibility do you think you have with that? Could you route that drainage to the 4 inch at the bottom of your drawing?

Is that a second story at the top of your drawing?

 

Thank you so much for replying so quickly! My apologies in the incorrect page. I can try to post in the other but assume I can’t move this one?

I suspect I can use AAVs out here too. Our code enforcement is more making sure the big boxes are checked and not too much else. I’m considering using an AAV for the kitchen sink, but was a bit worried about using it for the washing machine as we’ve had problems with our nice front load washer overloading the drainage pipes with its high powered pump.

Routing the washing machine drain past the upstairs toilet would be simple as the pipes are going through a large chase between the floors before dropping, but after the downstairs could be more difficult. What would be the reason to do this?

These are two bathrooms stacked on top of each other.

 

You can wet vent bathroom groups, cutting down on the number of vents you need. However, if you add a kitchen sink or a standpipe to the flow, you cannot wet vent.

Page 12 of https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf discusses IPC wet venting. Note that everything in that string of stuff is bathroom stuff. Also note that once the venting turns horizontal, it stays horizontal while the wet venting is in effect. Anyway, if you have a lavatory or shower that is vented along with a toilet, you normally don't need to separately vent the toilet. Also note that they bring the wet vented stuff in from horizontal rather than from above. Bring in non-bathroom stuff downstream of the bathroom group stuff.

A moderator could move this post to the plumbing forum, if inclined to do so. Otherwise, don't worry.

 

This is really helpful. Thank you.

I'm confused on this. How can an upstairs bathroom be brought in on the horizontal?

Here is a drawing with some edits. Am I getting warmer or way colder?

Thank you again for the help. For all "their" talk, the Internet can be a really friendly place.

 

lavatory drain comes into the horizontal pipe from above. The bathroom things that drain into that horizontal pipe enter the horizontal pipe from the side, not from above. So toilet joins the flow via a wye that is in the horizontal plane. I don't understand why that is important, but that doesn't matter. I could find you a discussion on the topic if you like.

After your toilet joins in, the bathroom group is done. You can go down then.

 

Okay I'm pretty sure I'm tracking you. I think my drawing is goofy? I plan on everything upstairs hitting the central horizontal upstairs drain from the side using wyes and long sweeps on the horizontal plane. I'll try for a bit clearer on my angles this time... (see attached)

 

Oops. Missed another rule. The wet venting can only be on the same floor. If you feed the lower floor toilet before via a wye in the horizontal plane, that lavatory on the same floor wet vents that toilet. Washing machine can take the shorter route into a sanitary tee or wye after it has been vented.

Toilet can be rear exit or not, but joins via wye in horizontal plane.. There are other configurations that are good. I am not a plumber.