For a true walk in shower, you will have to recess the concrete so the tile man can build a sloped mud bed.

we did walk in cultured marble saved alot $$$ and easy to keep clean,

That Schluter Kerdi system looks like the real deal way to go to me. I'm saving that info for when the time comes and I need it.

Schluter also makes a drain kit to fit existing drains.

I’m in the process of doing one now . Tore out the garden tub . Built a kneewall , used the Kerdi system including the pre sloped 48”x 72” pan . Had to extend it with dry pack but not bad at all . I had hardi backer on the walls and it was drying my thinset out real quick while trying to put the membrane on the walls . Ended up using a pump srayer to wet the walls and then the thinset was good and wet for awhile . Just make sure all is plumb and level and take your time with it . It is a very good system when done right . Utube has some good tutorials . I wanted to hire it out but its hard to find good help in Barbour cnty so i tackled it myself .
Good luck with the project
If you were closer i have some materials left over i’d donate to the cause

Exactly. That's why I was asking about what "walk in" ultimately meant for BowtechDan

Doing a true walking (no curb, no step up) on an existing slab will obviously complicate the installation. Key point to consider:
1. Where is the existing drain that served the garden tub? End, corner, side?
2. Location of existing rough in drain plumbing if to be left as is will dictate things. If you want to tear out and rework, you will have more flexibility.
3. Getting a positive slope with enough slope to the shower drain...from the open end and all side walls. You will have to make a recessed area in the finished slab to make this happen for a true walk in without curb or step up.
4. Schluter makes a nice linear drain that makes the sloping easier because the drain will pick up more water due to the configuration.
5. You need to run your waterproofing membrane system out past the shower entry door at least 3-4 feet (there is an exact spec but I don't remember it exactly), making sure you turn it up the perimeter walls. Open showers put more water than you realize out onto the regular floor. Not a super big deal on a slab...but you need to expect moisture creep under the tile going to any framed wall and the bottom plate. There will not be any slope there outside of the shower but for whatever variance there is in the slab when it was poured and finished. So for that reason the drainage mat needs to go out of the shower a little ways and up the wall 4-6" or whatever is specified to handle incidental water and keep it inside the membrane rather than migrating to your bottom plate framing. You will not have an end dam or turn up out in the open tile floor so you need to allow enough distance here.
6. I've seen many remodeled bathrooms that simply put the system over the whole floor in the bathroom to handle # 5 above.

Remodel...Call the man unless you know exactly what you are doing.

Ikillbux...new construction isn't a problem because the builder has opportunity to account for that shower in design and planning phases and then implement it correctly at pour and construction. What could go wrong? Seriously though, then can work that in and not have any trouble.

Easiest for him is to have a curb and build up inside to get enough slope. I don't think I'd want it with no curb even if I could .

Yeah, I'll have a small lip or curb to step over. The drain is placed normal in the tub on the left side. I'll make the wall on the left side about 6' high. Planning on replacing the window with a smaller one up high that will open up to vent. Need to find some bricks that match the exterior best I can. Need to figure out the tile design. Good thing is this room has a shower, so no rush to get it done once I start destroying stuff. When complete, I'll convert the smaller shower into a linen closet. Time to plan.

I’ve always used Laticrete 9235 over the Hardie backer board walls and over the floor mud in the shower floor. Like others said it is very important to properly install the vinyl pan according to the National Standards for the installation of ceramic, porcelain and mosaic tile. Getting the slope in the shower floor isn’t that difficult if you can read a level. Screw the drain up leaving about a quarter of it still threaded. Put some duct tape over the drain and cut it to fit. This will keep the floor mud out of your drain. Dump some floor mud around the drain and pack it good with a plastering trowel. Then make you a notch stick out of a piece of baseboard or screed stick about a foot long. Cut a gap out of the corner the thickness of the tile plus the thinset. Use this to sweep around the drain. Then add more floor mud from the drain sweep grade to a corner. Screed this with a 2,3, or 4’ level whichever works best to get the slope you are after. Doesn’t take much slope to drain. Once that screed is established then screed your floor mud level line corner to corner. Then work the floor mud screeding off your slope and level points while working your way out of shower floor. You can wet set your floor tile working off of floor boards which is a whole different skill set or you can let it dry and thinset it down.

I learned how to set tile before there was backer board and thinsets. We nailed metal lathe to the studs and did a scratch coat the first day. The next we muded it in. Wall mud was a mixture of mortar sand, lime and Portland cement. You set your mud sticks plumb and square and worked the mud with a hawk and trowel and screed it the access off with blade straight edges. Hard damn work. Then you had to soak the tile in number 3 wash tubs so it wasn’t so porous while installing it with white cement. Everything flat was mud wet set with gray cement working off of floor walk boards. Grout was made by sifting the large aggregate out of the mortar sand in a screen wire box and mixed with either white cement for the walls and gray for the floors. Not many master mechanics that now how to do these methods anymore.

Thinsets and backer board made the installation of ceramic tile a whole lot easier on your body. But it also opened it up to unskilled jack legs.

Definitely put two shower heads in it. Mines just a walk in without the door but we only put one head in it and I wish I had put one on either end

I used this system and worked great. I got the whole system, floor and wall. Very easy, just take your time!

If you do a small curb to step over you'll be in good shape for slope without having to rework existing slab.
Remember to not cut the corners of the membrane at curb and wall intersection...you'll be tempted to cut because the folding can often be troublesome; take membrane over and down outside of curb; seal both the holes and the screw heads of the metal glass clips that you put on the top face of the curb (pilot holes, fill with sealant, then install clips).

I've investigated dozens of shower leaks, most of which could have been very easily avoided.

99.9% of shower pan failures happen at the top of the curb due to failure to wrap the curb and the inability of the tile man to properly fold the pan and the waterproofing membrane. Some of the crap I’ve seen and replaced could have easily been avoided like Mike said. But then again I’ve seen pans nailed to studs below the shower drain head. I tore out one where the jack leg installer didn’t know how to fasten the pan to the drain flange so he just cut out a big circle and laid the pan over the drain.

What do you mean by "top of the curve"? Seriously asking. I'm planning on making sure the waterproof membrane is up high all the way around.

The step over that the shower door sits on. In the industry we call it a curb. Make sure you wrap it all the way over for a water tight seal.

Roger that.

I paid the man to do preslope, liner and mortar bed. I did the redguard and he checked the it all out. Then I tiled everything. I originally was gonna do Schulter Kerdi but didn’t know anyone who was really familiar with it. BTW, I would do the linear drain the next time.

Example of a 2 million dollar Bham area home with shower issues. Case has been resolved so I can post photos.

Curb


Glass Clip


Backer nailed through membrane at top of curb...no sealant


Resulting damage to curb


Cut corner of pan at shower floor and wall intersection; resulting damage to framing




Being on a slab will eliminate some of this from being possible, just take care of the curb to wall transitions and your wall perimeter corner conditions so your wall framing will not have issues down the road.

A curb should be sloped back to the shower, water proofed thoroughly and use pressure treaded lumber.

Those are great pocket knives.