A deadbolt lock is a simple, effective enhancement to home security, prized for the heavy latch bolt that extends into the doorjamb. A single-cylinder (e.g., single-key) deadbolt is keyed open from the outside, whereas a double-cylinder deadbolt requires a key from both sides. Double-cylinder locks help wherever an intruder might, by breaking a window, simply reach inside and unlatch a thumbturn or push-button lock. But anyone with a double-cylinder deadbolt should keep its inside key nearby in case of fire or other circumstance requiring a quick exit.
1.
Mark the Holes to be Drilled
Note: Deadbolts usually are placed about 6 inches above the doorknob.
1) Your deadbolt should come with a template for aligning the perpendicular lock and latch holes. Position the template on the door, securing it with masking tape.
2) Use an awl to mark the centers of the lock and latch holes.
2.
Drill the Holes in the Door
1) With a hole saw, drill a correctly sized lock hole in the face of the door. To avoid splitting the door's wood, drill halfway through one side, remove the drill, and finish the hole from the other side. The pilot bit hole will keep everything aligned. (Fig. 1)
2) Next, wedge the door open. Using a spade bit of the right size, drill the latch hole in the edge of the door. You'll eventually drill across the lock hole you just made.
3.
Install the Latch Plate
1) Insert the bolt and latch plate into the latch hole and, using a pencil, trace the latch plate on the door edge.
2) With a chisel, carve a mortise for the latch plate so that it will be flush with the door edge.
3) Secure the latch plate in the mortise with screws.
4.
Install the Lock Body
Note: Each lock manufacturer will have slightly different instructions for installing the cylinder assembly, but below are the general steps.
1) Install the assembly, joining the inner and outer cylinders with screws.
2) Test the lock's operation with the key to make sure it was correctly assembled.
3) Tighten any retaining screws.
5.
Install the Strike Plate on the Doorjamb
1) Partially close the door and mark the position of the deadbolt against the jamb.
2) Hold the strike plate in position and scribe around it with a utility knife.
3) Chisel a mortise for the strike plate as you did for the latch plate. (Fig. 2)
4) Holding the strike plate in its mortise, mark the position of the hole that will receive the deadbolt.
5) Remove the strike plate and drill the receiving hole in the doorjamb just deep enough to accept the length of the extended bolt.
