Jadnashua
Retired Defense Industry Engineer xxx
A flange gives you a wider flat/smooth area to create the seal with the wax against a continuous waterproof path to the drain pipe. Just putting wax on top of the pipe means you only have a very narrow ridge to protect the surrounding concrete (in your case) from getting constant moisture if the seal isn't perfect. Also, (more important on a wooden subfloor), the ring on the flange gives you multiple places to anchor it so you don't put stress on the pipe if the toilet is knocked. WIth the old CI pipe you have for the toilet, using one of the flanges that rely on the gasket will be tough with all of the rough, encrusted crud in the pipe now. They work okay on a new pipe and might suffice. Note, that seal is much more important if you ever get a clog, since normally, the waste is just passing by. if you have a clog, it could be standing there for awhile and soak into any leaking areas.
As to the 1.5" line and depth of the drain line under the shower, an inspector would not accept this. If your main drain line is ultimately low enough, it would be best and proper to remove what you have, lower the whole thing to get the proper pitch, size, and depth. My guess is that the main drain line must be deep enough since the toilet works.
As to the 1.5" line and depth of the drain line under the shower, an inspector would not accept this. If your main drain line is ultimately low enough, it would be best and proper to remove what you have, lower the whole thing to get the proper pitch, size, and depth. My guess is that the main drain line must be deep enough since the toilet works.