Before I get too much into planning, what should I be aware of in this existing configuration?

[ShelzMike]

The tub/shower would be better if the line were under the vent so that it can rise vertically. They don't allow a flat vent below grade anymore. After the vent is picked up, then you can 45 or 90 for the trap.

Tilting the combo at a 45 is also vertical, but vertical is easier to install.

Trying to conceptualize what you are suggesting. It sounds like you are saying run the waste drain so that it will actually run directly under the AAV venting pipe going up and THEN actually make the adjustments and bends to accommodate the trap. Essentially opposite of the way I have approached it here (with the line being directly perpendicular/under the tub drain and then doing some abstract bend art to get it to get to the vent).

I think that is what you mean and that actually makes more sense and probably should have done that initially.

I am a little bit thrown off about the flat vent though. I don't see where I have a flat vent, but maybe that is because I don't know what all would be considered a flat vent. Or were you just telling me to be sure I avoid using one when I reconfigure this? Not that I think it matters much, but this is not actually below grade. My house it build into grade and the back side of the house, where this bathroom is located, is 100% above grade, slab up .

 

[ShelzMike]

Yeah, so this is why this forum is so great. Terry's last message made me go back and take a second look and I realized that I had WAY overthought the initial change. This will be much easier and looks better also:

 

[Sponsor]

 

[James Henry]

Looks good. You may already be aware of this but if not, I would increase the last section of vent pipe going through the roof to 3" because it gets cold where you are and you don't want the vent pipe opening to freeze over.

 

[ShelzMike]

Thanks for the good word. About the last section of vent. I went back and forth and while I agree with your thought about it, that's the one thing I am going to leave. The reason why is because we love in SW Virginia and it doesn't get that cold here. We have lived in this house for nearly 20 years and that has never happened. The last section is galvanized also. We are doing all of this work to the house to sell it and buy something slightly larger and I am certainly not the "not my problem" type person, but it meets code and I just spent a ton on a new metal roof, I honestly don't want to get up there and have to work through it.

Is it a good idea to do so? Absolutely. Do I need to in order for it to be good enough? Probably not. So not doing it barely edged out doing it on the pro and cons list

Looking back, I also realized I almost/basically have a crown vent in my drawing for my bath sink. No worries though, it'll have at least a 4" tail on there. It was just how I drew it, not how I'll install it.