Do you need a pre slope in a shower.
No.I have installed a number of showers.There is no such thing as a single step process.If you don't have a pre-slope, or use something like Schluter's drain pans, the water will pool and just sit there, which will causebacteria growth, possibly mold, etc.
How much slope does a shower floor need?The minimum slope for a shower floor is 4 percent, which means a 1/2 inch drop per every 12 inches from the shower walls to the drain.The slope is established in the pre-pan in traditional tile shower construction.
The slope in the shower pan is meant to encourage water to go to the drain.There is a sloped mortar base under the tile and thin set.There is a liner on top of the slope.
The walk-in shower drain does not have to be in the middle.Linear drain can be placed on any edge.The water can be directed to a side or a corner if the floor is gently and unnoticeably sloped.A walk-in shower floor area could benefit from a smaller tile.