I'm starting a bath remodel. Second floor hall bath. The location where I want to place the toilet is such that it will be extremely difficult to do the plumbing from below. Is it common to pull up the subfloor to do the plumbing? I'm concerned about positioning of the toilet waste drain, reinstalling the subfloor, and then installing the closet flange. Is this a simple matter? Thanks
You can do it from above...just don't fall through!
The biggest things are maintain the proper slope, keep the venting working properly, and don't compromise the strucure.
Depending on whether you have 3 or 4" waste line for the toilet can vary what you do. Trying to maintain slope when moving with 4" can be a big challenge since the bends are deeper than available with marginal joists.
If the pipe is 4", it's easier since you can use an internal flange - just run the pipe high, install the subflooring, then the finished floor right up to the pipe, then install the flange after cutting the pipe to the proper height. If it is 3", you need to leave a space around the pipe to allow the flange fitting to slide over the outside of the pipe. If you didn't catch this - the proper position of the flange is the TOP of the FINISHED floor, not on the subfloor
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013