Help with horizonal drain run

I adding a new master bath to my first floor. I've attached photos of my pipe layout. Can you please comment on them. I attached two versions. One usings WYE's for venting and the othe using san-tees. Everything that I've read said santees on their back are no-no's. That's why I thought the first photo's were OK. Can you comment as well on the90 elbows for the vents. My vents are offset from the horizontal run. SO I thought that 90's or 45 could be used, although I read that you can't go horizontal on a vent until 6" over highest fixture. But I've seen books that show vent horizontal under showers and then 90 towards roof. Also, can the WYES be used one side like shown, or do I need to raise them 45 or more

Thanks in advance for all your help.

I don't think any code allows the santee on its back for a vent. Also, as you surmised, the horizontal part of your vent run is not acceptable. For that, if you rolled the wye over, you might be able to run that line up at 45º then go vertical inside the wall.

I saw this diagram in a book and it was confusing. Not only did it vent using Santees, is vented 90 degrees then up.

So getting back to my layout. I tested rolling the WYES for venting, and they will work. Are the WYES for the discharge OK to use with a side-entry like shown? Does everything else look like its up to code?

Dwv

The "vent" for the tub/shower is completely ineffective at that location. It should be connected between the "Y" and the trap. There are many better ways to run the vents than your drawing. Most of them would involve using "combination Y-1/8 bend fittings".

So you would move the vent WYE from upstream of the trap and place it between the trap arm and the main WYE. COuld I come off the main WYE with a 45 bend, then the vent WYE rolled to 45 then the trap arm?

So here is my new layout idea. Main branch 3". Each fixture on its own branch attaching to main with WYE. Added WYE COMBOs rolled to 45 on each branch to pickup the vents

Does this look better?

Yes. That works

If a demanding person doublechecked this, highpeakscontracting, he'd ask you to answer this: how many feet is the distance run by the 3" pipe from the point it gets upsized from 2" to 3" until the point where the vented 3" WC pipe connects to it ?
-- Secondly, describe what happens where you have not yet drawn the Wye for the cleanout and vanity.

I'm looking at the image trying to understand WHY you upsized.

Hope this helps.

I like the new stuff too. (pictures)

Interesting install,
So you're going to extend the 3" above the floor for the end of line c/o and reduce down for the lav? That works. Without adding confusion, have you thought about wet venting the lav into the shower vent? You'd have to increase the vent to 2" until you added the lav waste but it saves drilling holes in wood. Just a thought. Btw, don't forget your purple primer! Good luck!