How to Change From a Mortise Lock to a Knob Set

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Mortise locks may have wavered in popularity over the years, but they remain a common way to secure a home. However, many homeowners prefer the newer cylindrical type of lock set, which doesn't require such a large pocket in a door. If you're moving from a mortise lock to a knob set, you'll need to first remove the mortise lock. Before you can install the knob set, though, you must fill in the extra space that was originally cut in the area where the door meets the doorjamb when closed. Once you've prepared the area for the new knob set, you'll install the face plate on the doorjamb, insert the doorknob into the door and test the lock to make sure it works.

How to Change From a Mortise Lock to a Knob Set
Image Credit: SasinParaksa/iStock/GettyImages

Removing a Mortise Lock

Before you can remove your existing lock, you'll need to make sure you have the correct replacement lock ready to install. You should also have a drill, a screwdriver and a hammer on hand, as well as a door lock installation kit, which can be found at most hardware stores.

You'll first remove the screws holding the doorknob in place, then turn one side of the doorknob in a counterclockwise motion until the doorknob separates. At that point, you can undo the two screws on the mortise and pull it out of the doorjamb, using a pair of pliers for extra leverage if necessary.

The next step of the process involves filling the extra space left by the mortise removal. Cut a wooden block to fill the entire space, checking to make sure it's a good fit before putting glue on the sides that will fit inside the door. Slide the block in place and hammer a 1-inch finish nail to lock the top of the block in place. You are ready to install your new lock.

Installing a Knob Set

The easiest way to create a space for your new doorknob is with a door lock installation template, which is sold as part of the installation kit mentioned above. The template will fit over the doorjamb and help you drill the exact holes you'll need. Place two screws from your new door lock kit in the doorjamb to hold the template in place, then use the bit from your lock installation kit to drill a hole where the new doorknob will go.

Once you've removed the door lock template, you have a space perfectly primed for your new lock. Paint over the block to match the rest of the doorjamb. Install your new lock, then the doorknob and mark on the doorjamb where your matching strike plate should go so it will perfectly line up with the new lock on the door. Install the door plate with two screws and test the lock to make sure it works.

Cylindrical locks are usually less expensive and sturdier than mortise locks, offering an incentive to make the switch. With the right tools and DIY confidence, you can complete the task in a matter of minutes and begin enjoying your new lock.


Stephanie Faris

Stephanie Faris

Stephanie Faris is a novelist and freelance writer whose work has appeared on the websites of Pacific Standard, the New York Post, the Intuit Small Business Blog, and many others. She is the Simon & Schuster author of eight children’s novels, including the Piper Morgan series.