Step 5 · Level and Secure the Pan
Immediately after setting the pan in the mortar, place your 4-foot level across the top thresholds. Check for level side-to-side and front-to-back. Gently press down on any high spots to bed the pan further into the mortar until it is perfectly level in all directions. The pan's built-in slope will handle water drainage; your job is to level the top edges. Once level, drive 1-1/4 inch galvanized screws with washers (or galvanized roofing nails) through the pre-drilled holes in the pan's mounting flange and into the wall studs. Do not overtighten the screws, as this can crack the flange; drive them just until they are snug.