This was a first for me, too--and a big departure from the original design. The orignal drawings for the bath were for a deck mounted tub with a curbed shower beside it--the glass for the shower stepping around the deck as is typical.Very Nice!
Is that a recessed tub in the master bath? Any framing pics of the tub install? Or a brief discription how it affected the space below?
My company did a step down shower before I started with them, I've done work there since and I was shown how they lowered the ceiling in the a garage. I like that feature.
This bath was over crawl which made it fairly simple to frame for the sunken tub. Once the opening was headered into the floor, we built a platform for the tub that was essentially a mini-deck:
4"x4" posts set on footers and in concrete, with a 2x12 structure and 3/4" osb subfloor. We built the platform low enough to allow the tub to be set in a mortar bed for final leveling.
Here are some progress photos:
The shower drain was roughed-in before the switch to the curbless shower. It was later cut out and the floor was re-framed to receive the pan for that:
We used two different thicknesses of floor backer to level the porcelain and glass mosaic tile to one another.
Kerdi was applied to the walls and floor before tiling.