How to Replace a Mortise Lock

Exterior doors are secured using either cylindrical or mortise locks. A cylindrical lock is installed through a small hole that is cut in the door. This is the type most commonly found in homes. A mortise lock is installed in a pocket that is mortised out of the door. This is a much more secure application, and also more expensive. While mortise locks can be more difficult to work with, it is still possible to complete this project on your own, without paying for an expensive locksmith.

Difficulty: Moderate

Instructions

Things You'll Need:

• Screwdriver or drill
• Allen wrench (optional)

Remove Existing Lock

1. Remove the door knobs from both sides of the door. There may be visible screws around the knob, or they may be covered by a metal plate, called a rose. If your screws are covered, simply grasp the rose and pull it gently away from the door. You may have to twist it a bit to loosen it. Once you can see the screws, remove them and gently pull the knobs off the door.

2. Open the door so that the edge of the door is visible. Remove the screws on the door's edge that are holding the cover plate in place. Once these screws are removed, you can easily remove the cover plate to see the lock body.

3. Remove the set screws. These are the screws that are holding the lock body in place. Once these are removed, simply pull the lock out off the door.

Install the New Mortise Lock

4. Purchase your lock. Choose a model that is made by the same manufacturer (Schlage, Sargent or Best) as the lock you removed. This is necessary because each manufacturer configures its locks a bit differently, and if you purchase a different brand, you may have to make complicated adjustments to your door.

5. Place lock body into door pocket. The lock should be placed so that the hole for the cylinder is on top, and lines up with the cylinder hole in the door.

6. Screw the lock body in place using the screws that came in the package. Each lock comes with a template showing where these screws should be placed for that particular model. Refer to the template that came with your lock to figure out where your screws should go.

7. Set the knobs in place on each side of the door and screw them in place according to the template.

8. Install the lock cylinder. This is the small round device where the key will be inserted to operate the door. The cylinder should be threaded into the lock by hand. Make sure the keyhole is at the bottom half of the cylinder after you have installed it.

9. Screw the faceplate into place on the side of the door to cover the lock body. If you removed your old strike plate from the door frame, you can replace it with the strike plate from the new lock you purchased. It should be screwed in place per the template.