How to Install a Prehung Exterior Door Into a 2-by-6-Foot Framing
- 1). Set the door unit in the doorway, still in its packing restraints so it's kept closed. The hinge pins must be on the inside of the house, and the door should be positioned to open in the direction you want.
- 2). Slide shims around the door unit, between the casing and the surrounding frame, while holding a level alongside the inner edge of the casing. Hold the level at various points around the doorway while shimming it, until it reads level all around.
- 3). Cut the packing restraints off the door with your razor knife and open the door, so you can access the inside spans of the casing.
- 4). Drive 3-inch galvanized screws through the casing and into the surrounding frame all around with a screw gun, putting the screws about 2 inches in from either edge of the casing, every 16 inches or so.
- 5). Cut off the overhanging shims with a razor knife. Spray foam insulation in around the gap between the casing and the frame. Door trim will cover the gap around the door inside and out.