Before removing the old door, confirm the replacement unit matches the existing opening in width, height, jamb depth, and swing direction. Gather all necessary tools and safety equipment. Carefully remove the interior trim and take the old door off its hinges. If replacing the full frame, remove the old jamb and any remaining fasteners, taking care not to damage the surrounding area.

Once the old door is out, closely inspect the rough opening for damage, rot, moisture, and uneven surfaces. Clear away all dust, old caulk, nails, insulation, and debris. Repair any damaged areas, fill old hardware holes, and ensure the opening is solid, level, and completely clean before moving forward.

Apply flashing and caulk along the opening to create a weather-tight barrier against air and moisture. Carefully set the replacement door into position and check for level, plumb, and square. Use shims around the jamb to fine-tune alignment, then secure the frame with screws, ensuring nothing twists out of position.

Open and close the door several times to confirm smooth operation and proper alignment with the strike plate. Make any necessary shim or screw adjustments until movement feels even and effortless. Once the fit is confirmed, insulate around the frame carefully, avoiding overfilling, which can warp the frame.

Reinstall or replace interior and exterior trim for a clean appearance. Seal the exterior perimeter with paintable caulk and install all hardware including the lockset and latch. Do a final check to confirm the door opens, closes, and locks correctly, leaving the installation fully protected against weather and everyday use.