I'm an advanced D-I-Y guy renovating a 5' x 7' "kids" bathroom.
I demolished the old bathroom. Jacked up and repaired cut floor joists with an LVL beam. I demolished the rusted galvanized steel and cast iron D-W-V lines and stack from the roof to the basement. I installed new D-W-V PVC from the basement to the roof. I set the shower stall rough in to fit the Schluter Kerdi 32" x 60" shower kit with the 10" drain offset.
Ran a new sub-panel up to the second floor to provide GFCI lines for both master and kids bathrooms (lights, outlets, radiant floor heat) as well as new and more lines for the second floor.
New Viega PEX 3/4" lines for both the new bathroom and the old "Master" bathroom (to be renovated in the future.)
All walls furred and shimmed out to flat and plumg(nightmare), exterior wall insulated heavily, floor joists were sister-ed and leveled to approximately 1/32" of accuracy. All the perimeters were blocked to support the plywood edges and extra homemade OSB beams were glued and screwed, then installed under the toilet and sink positions for support. This all took some time as there was lots of sag and plans kept changing.
Ran all new electrical with roughs for the radiant floor heat.
Cut a hole in the ceiling for a good quality Fan/Light/Nightlight unit. Cut a hole in the roof to vent it with a best quality flapper valve.
Then I put down the 3/4" OSB subfloor and green boarded the walls.
As stated I will use the Schluter Kerdi 32" x 60" kit as the foam pan's drain placement was allowed due to my unique framing situation.
I also knew that I would have to platform the shower stall pan 1.5" from the OSB subfloor, as I need this to allow sufficient space for an adequate drain line pitch, and space between th P-Trap and Kerdi drain flange tail.
I have three sheets of .5" Durock Next-Gen and plan to cut, fit then stack and screw them into the shower stall area. Is this a good idea? Should I instead just get another sheet of 3/4" OSB and cut two sheets to fit?