How to Replace a Door Knob with Lock | Keyed Entry Swap

For the full breakdown, see our best Door Knob Lock guide.

Most exterior keyed knobs follow the same swap whether you’re updating a front door or rekeying a side entrance. Skipping the fit check is what causes frustration—a lock that doesn’t match your door’s thickness or backset won’t seat properly, and the assembly binds when you turn the key. Checking those two numbers first makes everything else go smoothly. Here’s the sequence in the order you’ll do it.

Check Door Thickness and Backset Before You Start

Before removing anything, confirm your door matches the new lock’s requirements. Schlage’s prep documents specify their keyed knobs fit doors between 1 3/8″ and 1 3/4″ thick; a door outside that range won’t let the lock function properly. Measure the door’s edge at the bore hole. Backset is the distance from the door edge to the bore hole’s center. Kwikset’s instructions call out two standards: 2-3/8″ (60 mm) and 2-3/4″ (70 mm). If your old knob used a 2-3/8″ backset and the new one ships as 2-3/4″, the latch usually rotates to adjust. Also check the bore hole pattern: a keyed entry knob needs a 2-1/8″ diameter bore plus a smaller latch bolt hole.

Remove the Old Knob and Latch

Depress the release tab on the interior knob’s shank with a flathead screwdriver while pulling the interior knob off. Remove the two mounting screws holding the exterior rose and knob, then pull the exterior half out from outside. Remove the two screws on the latch faceplate (the metal plate on the door edge) and pull the latch straight out. Finally, remove the strike plate from the jamb with its two screws. With everything out, wipe debris from the bare bore hole and latch slot so the new latch seats cleanly.

Install the New Latch With the Bevel Facing the Jamb

Slide the new latch into the edge hole with the beveled side facing the door jamb. Schlage’s instructions state: if the bevel faces the wrong way, the latch bolt won’t retract when you close the door—it will catch on the strike plate. Slide the latch in until the faceplate sits flush against the door edge. If it sits proud, trace the outline with a utility knife, chisel out about 1/8″, and make it flush.

Mount the Exterior and Interior Assemblies, Then Test

From outside, insert the keyed exterior assembly so its mounting posts pass through the bore hole and align with the latch’s drive mechanism; check the tailpiece engages the latch. From inside, slide the interior turn piece over the posts and secure with the mounting screws. Install the strike plate on the jamb: close the door, mark where the latch bolt contacts the jamb, remove the door, hold the strike plate in position, and trace its outline. Test the lock several times from both sides: key the exterior cylinder, turn the interior thumb piece, and close the door to confirm the bolt engages cleanly. If the door binds, check the strike hole alignment and that both plates are flush.

FAQs

What if my door is thicker than 1 3/4 inches?

Most residential keyed knobs won’t mount flush on a thicker door. You’d need a lock with longer mounting posts or a commercial-grade unit. Check the manufacturer’s spec sheet for max door thickness before purchasing; forcing the assembly typically strips screws or leaves the rose loose.

Can I use the existing strike plate with a new lock?

Yes, if the holes align. Compare the new latch bolt position against the existing strike plate—if the bolt lands in the same spot, reuse it. If it sits slightly higher or lower, install the new strike plate instead, mortising it flush.

Why won’t the latch bolt retract when I turn the knob?

The most common cause is the latch bevel facing the wrong direction. The beveled edge must face the jamb so the bolt pushes inward as the door closes. If it faces the room, the bolt jams against the strike plate. Reinstall the latch with the bevel reversed.