Usually we see a four in pipe sticking up out of the floor and after the floor is fixed the pipe is cut flush and a 3-4 flange fits inside.
Maybe the reason this approach wasn't taken is because the flange has to be on an 90 degree elbow pipe (in order to connect to the rest of the drainage pipe running horizontally thru the foundation), and there wouldn't have been enough space to get a good fit because of the curve of the 90 degree elbow.
The plumber had charged me $400 ($80/hour for 5 hours). Quite sure I got ripped off and didnt want to deal with their bull**** again, so I decided to research it more and just finish it myself.
First I used a wire brush on the edges of the existing concrete and I cleaned up the area. Then I loosened the coupler and get the elbow/flange level. No way to move it down closer to the floor though:
I retightened the coupler to the point where there was little-to-no give on the elbow, but did not apply any adhesive to the pipes (hoping this doesn't come back to bite me). I ran some water down it and felt for leaks, seemed good, so I then filled it in the hole with pea stone gravel, making sure to work it in the tight spaces around and beneath the pipe:
I applied Quickcrete bonding adhesive to the edges of the existing concrete, let it dry, then mixed up some Quickcrete 5000 high strength concrete (I had extra lying around) and patched in the remaining 2 or so inches. The 5000 has got a lot of gravel in it, so getting the top smoothed off was a challenge for me (again I'm a noob):
If I was a smarter person, I would've done a dry fit with the toilet and the new toilet flange before patching in the concrete because the room is TINY and if the toilet flange has moved by more than an inch, the bathroom door will hit the front lip of the toilet. But I measured it, seems ok, I'll do a dry fit once the concrete cures, and use my forehead to smash the new concrete if it doesn't fit.
So the remaining issue is that the metal flange will still be a 1/4" or so above the new tile. To secure it, I think I'm going to get some of these
composite shims, and silicone them to the tile underneath the flange, and then bolt the flange thru the shims + tile + concrete with concrete anchor bolts.
Thoughts?
