Verify the subfloor is solid, clean, and level
Install and secure the drain assembly
Apply a moisture barrier or roofing felt over the subfloor if required
Staple down metal lath if using a traditional mortar bed
Mix deck mud to a damp, packable consistency
Mark the perimeter height for the shower pan slope
Pack a level perimeter screed around the shower base
Build the pre-slope from the drain to the perimeter at about 1/4 inch per foot
Compact and smooth the mud firmly
Let the pre-slope cure if required by the system used
Install a shower pan liner over the pre-slope if using a traditional system
Clamp and seal the liner to the drain
Fold corners neatly and avoid puncturing the liner below the curb height
Perform a flood test to check for leaks
Place a second mortar bed over the liner if using a traditional shower pan
Maintain the same slope toward the drain
Pack and smooth the final mud bed
Allow the pan to cure fully before tiling
Follow the specific instructions for prefab or foam shower pan systems if not using mortar