The floor of a tile shower, commonly referred to as the shower "pan," is a hard-packed mixture of sand, preferably "sharp" sand which is crushed rock, and traditional Portland cement over a vinyl or PVC membrane. Properly installed, the shower pan provides a watertight seal for the shower floor and a sturdy base for the stone or ceramic tile finish. The basic recipe for "floor mud" or pan mud used by professional masons is easy to mix and ensures a solid substrate for the shower floor.
Things You'll Need
Wheelbarrow or mortar mixing box
Mason’s hoe or flat shovel
Plastic bucket (optional)
Place 10 approximately equal shovel scoops of sand into the wheelbarrow or mixing box.
Add one shovel full of Portland cement to the sand and mix thoroughly with a shovel or mason's hoe, drawing the material back and forth over itself to reach an even mixture. The amount of mix can be increased, if needed, following the basic ratio of 5 parts sand to 1 part Portland cement.
Continue to turn the mixture over and over with the shovel or hoe and begin to add a small amount of water. Add the water to the sand-cement mixture until the mix is thoroughly damp, but damp only and not wet. Test the moisture content by squeezing a handful of the damp mixture in your hand. The mixture has reached the proper moisture content and is ready to install in the shower pan when it will pack into a ball without crumbling and the entire batch is consistently damp.
Do not panic if you add just a bit too much water. The mixture can be “dried” by adding sand or cement, but try to adhere to the 5:1 mix ratio as closely as possible.