Plumbers....adding a shower drain questions

4spdragtop said
Hi all, doing a remodel in basement. Extending the shower drain and adding a back flow preventer. Extended approx 3 feet. Now with the slope it puts the p trap connection to straight pipe approx 1/2" above the existing concrete. I was going to "backfill" with gravel that I removed, then top with concrete and then floor leveler, finally topped with a layer of dricore.(7/8" thick)Then shower base. Bathroom is small approx 50-60 sq ft.
I'm kinda wondering how to go about this?? In the 3rd pic the small level is where the p trap connects, and it sits approx 1/2" above concrete at the edge.
Where the larger 4' level runs side to side, that is where the leading edge of shower base will be. ABS sits flush with concrete right there.
Sika floor leveller and then dricore for subflooring throughout.
Looking for some guidance here.
Thanks
Steve
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Im a plumber. So first of all you need a p trap centered under the shower base. Use 2inch pvc from the abs pipe connecting it with a rubber fernco. If the abs pipe is 1 1/2 use a 2 by 1 1/2 fernco to connect the pvc to the abs. Another thing is i dont see a vent fot the shower. If there's no vent the shower will gurgle when another fixture is used. It will not drain as well either. Pit a 2 by 1 1/2 1inch wye in before the trap and run 1 1/2 pvc to the wall where u can stub up the pipe 4 ft and install a auto vent on top.