39 x 79"? Existing slab [flat] -resolve drainage issue with a sloped base/ power chisel, some hydraulic cement, and a thin set water proofing membrane system for finish tile to mount onto. Your wall substrate- if older house likely sheet rock on your walls. At best maybe some green board (moisture-resistant sheet rock). Most current codes will require a cement backer board for tile in wet areas, e.g., Durock. This would go over your wall waterproofing membrane. floor to slope to the drain? It’s like a typical drain in a custom shower base, however, in this instance it was notched into the existing floor joists and extra structural support was added. It is a bit tricky; hire a competent qualified contractor with experience doing these types of installations. Check local building codes, and if structural work needs to be done you will most likely need the help of an architect or structural engineer.
consider how remaining floor will be prepared when choosing shower drain too. This bathroom was built and waterproofed with the Schluter Kerdi and Ditra system, which allows for a seamless transition from the dry area to the wet one. Tip: Use a temporary dam to flood test these installations. You will need to dam the shower 2 inches above the entry point.
To ensure water drains away effectively, first create a gentle slope in the floor. 2 ways: buy pre-formed tray that is set into the floor and tiled; or spreading a levelling compound to form a slope. ‘Experienced installers may be happy to fabricate a “tray” themselves by preparing the sub-floor – for example timber joists – cutting plywood accordingly, and tanking on top of this'. There should be no movement in the floor, so a ground floor location is good. Small tiles can wrap around shapes. Large tiles have to be cut properly.
or one high window