How To Build A Shower Pan -- The Subfloor
Information about how to build a shower pan starts with the right foundation.
Ceramic tile surfaces crack when they bend just the slightest little bit. The standards for tile laying call for deflection between 16 inch spaced joists of no more than 0.04 inches. That's not very much...
That's why the joists must be rigid, with almost no bending. Plus the subfloor must be rigid too.
If you're working with a plywood subfloor, you want at least a single sheet of 3/4 inch plywood. Two sheets stacked are even better providing there's enough vertical clearance for the two sheets.
Don't take shortcuts, get the foundation for your tile shower floor right.
Bouncy subfloors equal cracked tile shower floors...
At this link read the next article about preparing the subfloor for a shower pan installation.