Step 2 · Install the Drain Fitting
Turn the shower pan upside down on a protected surface. Following the manufacturer's instructions for the shower drain assembly, apply a continuous bead of 100% silicone caulk or a ring of plumber's putty to the underside of the drain flange. Insert the drain fitting from the top side of the pan so it sits flush. From the underside of the pan, slide the rubber gasket over the drain threads, followed by the friction washer (if included), and then thread on the locking nut. Hand-tighten the locking nut, then use channel-lock pliers or a dedicated drain wrench for a final quarter-turn to create a watertight seal. Scrape away any excess putty or caulk that squeezed out.