Masonite Exterior Door Installation Instructions

Lay a level on top of the threshold. If it is uneven, nail shims to the threshold every 6 to 8 inches. Trim the edges of the shims with a utility knife.

Cover the threshold with adhesive-backed aluminum tape.

Apply two thick beads of silicone caulk to the sides of the door frame and across the threshold on the aluminum tape.

Move the new Masonite door into the doorway. Have someone help you if you're having trouble handling the door. Lean the top of the door away from the house while you place the bottom on the threshold. Push the door upright into the door frame.

Hammer two nails partway through the flange in each upper corner of the door to hold it in place temporarily.

Measure the door frame diagonally in both directions to check it for square. If the measurements are different, install shims between the framing and the edge of the door, then take the measurements again. Adjust the shims until the measurements match.

Using the level, check the door for plumb (vertically straight) and level (horizontally straight).

Measure the gap between the door frame and the edges of the door on both sides to see if it's centered. If it's not, add more shims until it is. Trim all of the shims around the door.

Drive nails through the flange around the edges of the door every 6 to 8 inches. Remove the nails in the upper corners of the door that you used to hold it in place.

Place aluminum tape over the nailing flange on the door's exterior.

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

Nail the drip cap to the top of the door frame, then nail the trim for the sides of the door in place.

Apply a thick bead of silicone caulk along the joint between the trim and the house.

Paint the frame around the door.

Insulate the area around the door frame on the inside of the house with fiberglass or spray foam insulation. Cover the gap around the door with the interior casing.

Install the latch and deadbolt on the door.