Please Critique Basement Bathroom Drain Rough Plumbing Plan

[rcalliott]

Looking for feedback on my planned drain rough ins before I start busting concrete to build a basement bathroom with a sink, toilet, tub/shower combo.

Blue tape represents existing 4" PVC drain pipe under slab.

PVC Fittings from left to right:

• AAV (in the box) atop 2 inch tee serving the sink drain (will be recessed behind the drywall in the vanity).
• Next is a 2" long sweep 90 degree turn from vertical to horizontal.
• Then a 2" 45 degree fitting to get the pipe slotted into the 3x3x2x2 Double Wye.
• Double Wye serves toilet above it via 3" pipe, and connects to 4x4x3 45 degree wye attached to existing 4" pipe 12" to 15" under the slab.
• Fernco fittings with PVC stubs to attach wye to existing drain pipe, which flows from left to right in the picture.
• From the right of the Double Wye is a 2" pipe with various 45 degree fittings to get the angle correct to the 2" p trap for the tub/shower combo (furthest item on the top-right).

With a wet vent from the sink, my understanding of the toilet NOT being the last fixture on the pipe requires the Double Wye/Symmetric Fitting.

Seems like some folks don't care for the AAV. on the other side of the top wall is my workshop with access to the main stack and a vent that goes up through the roof. If the AAV functions poorly in this configuration, I can tap into this 1.5" vent pipe...its just a pain I'd like to avoid.

Any feedback and general comments/suggestions are appreciated.

 

[Sylvan]

GET rid of the fernco coupling. Go with shielded couplings

 

[Sponsor]

 

[rcalliott]

Will these do the trick?

https://www.menards.com/main/plumbi...exible-coupling/1056-44rc/p-1444430427234.htm