How to Replace an Old Mortise Lock for a Door

Doors are generally secured with one of two types of locks. A cylindrical lock is installed through a small hole cut in the door. This lock is inexpensive, but not as secure as the other option, which is a mortise lock. The mortise lock is installed into a pocket in the door, making it an integral part of the door itself, which provides a high level of security. If you are simply replacing a mortise lock, the door will already be prepped to accommodate the lock. This task can be completed in just a few hours using only basic tools.

Difficulty: Moderate

Instructions

Things You'll Need:

• Drill
• Screwdriver
• New mortise lockset

1. Start by removing the door knobs or levers. Slide any cover plates, or roses, away from the base of the door so you can see the screws. Remove any screws you see using a screwdriver or drill. Holding one knob or level in each hand, pull the handles away from the door until they are removed.

2. Remove the cover plate from the edge of the door. It will likely be held in place with two to four screws. Once these screws are removed, you can remove the plate to expose the lock body.

3. Determine how the existing mortise lock is held in place. It will likely have only a single set screw. Once this screw is removed, you can pull the entire lock body out of the door.

4. Take your mortise lock to your local home improvement store. Buy a replacement mortise lock that is from the same manufacturer as your old one, whether it is Shlage, Best, Sargent, or another brand. Each lock manufacturer uses different lock sizes and screw locations. If you switch brands, your door could require some difficult prep work.

5. Remove the lock from the package and look for the template. Every lock should come with one of these templates, which shows how to install the lock and where the screws should be placed.

6. Place the lock body into the door. The hole for the cylinder (where the key is inserted) should be on the upper half of the lock, so that the hole lines up with the hole in your door. Install the set screws for the lock as shown on the template.

7. Screw the cylinder into place. Make sure you are placing it so that the keyhole faces to the exterior of the house. It should be threaded so that it can be screwed in by hand fairly easily.

8. Slide the door knobs or handles into place. Push them gently towards the face of the door until they click into place. Install any screws that are indicated on the template to hold the handles in place. If there are roses or cover plates, slide them flush against the door until they are tightly in place.