Hello HU, off the top of my head... full stone slabs have been considered normal practice in the higher end building industry for many years now. Having previously installed full slabs of granite/quartz/rugged sandstone/semi precious stones etc in clients showers before, I'd tell you to definitely consult your building plan and/or a structural engineer if you're uncertain...Some showers slabs can be 12 feet long & when stacked on top of each other can weigh half a ton. Most of the stone slabs I've used in showers were 1" to 1.5 " thick. Since you didn't mention any dimensions, we can only speculate...Your walls need to be built solid & your shower base level, but the reinforcing should all be done mainly in the floor below....don't forget, the walls holds almost none of the weight, it's all in the floors. If you have another story/s below, typically a new structural beam or beefing up in the ceiling below is in your future. If you're on slab, cutting it, tying in additional rebars & repouring, or whatever your structural engineer wants to see in order to stamp & pass it. Additionally, the plumbing must be done PROPERLY & pretested, there's no going back once that slab goes on. A couple of positives are a complete minimum amount of grout/joint lines, as well as an no sealing slabs, as this is pre done during fabrication. Still, I'd advise you to pick your stone carefully, as some cosmetic choices can become a long term disaster in regards to practicality, cleanliness etc. This is mainly due to porosity issues. Lastly, If you're using a very light natural stone or semi precious & want lighting to illuminate from behind, please be aware of using only very specific mortars for this effect to work. Good luck !

Thank you so very much for your input. My slab size 64” x 127”. The largest wall is an outside wall and I have concret floor, single story. This is polished quartz from Bedrosians and only comes in 2 and 3CM opal background with very light veining.

HU:

No wall or floor reinforcement is necessary for the installation of slab walls on a modern building.

You bring walls to the panels with shims, not panels to the walls with rebuilding..