Most exterior doors that are sold on the market today are of the pre-hung variety. However, there may come a time when you need to know how to hang a door in an existing jamb, replace a jamb or install a jamb and door in a new opening.
Inspect the current door jamb to assess the viability of it supporting a new door. Look for cracks and damaged, especially in the area where the hinges must be place. You can purchase a jamb kit, which includes two side jambs and a header. The typical dimensions are 9/16 by 4-3/8 inches.
Position the first hinge 7-inches from the top of the door. Set the pivot point, or pin, ¼ inch from the edge of the door. Place the pin on the side where the door will open. Depending on the size of the door, you may have three hinges. The bottom hinge should be about 11-inches from the floor.
The depth of the hinge cuts, or mortises, should be the same thickness of the hinge leaves. Remove the wood by making some small cuts across the mortise outline and work with a sharp chisel with the beveled edge pointing up.
Cut the Mortises
Work with the jamb on the floor. Place the door in the jamb. The gap between the jamb and door must be 1/16 to 1/8 inch. Use shims as necessary. Shims are wood wedges use to level and secure doors and windows in openings. Mark the spot for the mortises on the jamb.
Install the Jamb
Install a Z-flashing above the header. This is metal flashing designed to keep moisture from penetrating this location. Center the jamb in the opening. Focus on getting the correct fit at the top of the jamb. Use shims about every 12 inches to get a tight fit. Use 8d nails. Drill pilot holes and fasten into the shims to secure the jamb header.
Proceed to level the hinge side of the door jamb. Drill pilot holes and partially insert nails at the top, middle and bottom. Install the hinges, but pre-drill the pilot holes for your screws. The screws must be flush with the hinge leaves. Do not secure the latch side jamb.
Set the Door
Put the door in place and insert the pins partially into the barrel. Open and close the door as you test for the fit. The door should function freely. The gap should be uniformed on the top and at the sides. If the door swings on its own, it is not level. You may have to insert more shims to get it right. Make sure that the hinge pins are inserted all the way in the barrel Check that the door is flush with the edge of the jamb when closed.
Install the knob and locking mechanism. Mount door stops at the top and on both sides. Use 4d nails to secure the stops, make sure that the door flush against the stops before you drive the nail in. Use a block when driving the nails in place to prevent damaging the jamb. Caulk around the top and the sides of the jambs. Put in the door casing.