How to Install a Pre-Hung Replacement Front Door

Check the threshold for level across the bottom of the door frame. If uneven, nail shims to the threshold until it is level.

Place two strips of adhesive-backed aluminum tape on the threshold. Run the ends of the tape 2 to 3 inches up the side jambs of the door, and overlap the edges of the strips where they come into contact.

Apply two thick beads of silicone caulk across the threshold on the aluminum tape. This will prevent water from seeping underneath the door.

Place the bottom of the framed door just in front of the threshold with an assistant's help, and lean the top edge of the assembly out away from of the house. Push the top edge of the assembly into the wall opening and position it.

Secure the door frame temporarily by driving nails partway into the flange in the upper corners.

Check the door for square by measuring the distance across the door diagonally in both directions. If the measurements are different, slide shims in between the wall frame and the door frame until the measurements match. Nail the shims in place, and trim the excess off with a utility knife.

Secure the door frame to the wall by nailing the flange to the wall. Use one nail every 6 to 8 inches around the door.

Place aluminum tape over the joint between the flange and the wall across the top of the door frame.

Cut a 2-by-4 board to fit across the top of the door, then glue a drip-cap to the board with carpenter's glue.

Nail the drip-cap board to the wall across the top of the door frame.

Place the side trim on the wall against the outer edge of the flange, and nail it to the wall. Run a thick bead of caulk along the side trim and the top of the drip-cap.

Cover the frame with primer and allow it to dry, then paint the frame, if the frame is made of wood. Skip this step if the frame is made of metal or a composite material.

Apply spray-foam insulation between the door frame and the wall frame on the inside of the house.

Install the casing around the interior of the door frame.

Install the lock and door handle, following the manufacturer's instructions. If already installed, skip this step.