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.