How to Add a Second Lock to an Existing Front Door

Position the cardboard lockset template included with the lock against the door at the desired height. Note that the vertical line printed on the template must align with the interior edge of the door.

Tape the template to the door.

Mark the center of the lock hole on both sides of the door and the center of the latch bolt hole on the edge of the door with a nail. These points are noted on the lock template. Tap the nail into the center mark on the template with a hammer just until the tip of the nail penetrates the door.

Remove the template.

Insert the pilot in the center of a hole saw into the notch marked by the nail on the interior side of the door, then drill into the interior of the door with the hole saw just until the hole saw pilot penetrates the exterior of the door. Remove the hole saw and finish boring the hole from the exterior-side of the door.

Insert the tip of a spade bit into the notched marked on the edge of the door and drill through the edge of the door until the bit penetrates the door and enters the lock hole bored in Step 5.

Slide the latch bolt through the hole cut into the edge of the door, then secure the latch bolt in place with the included screws.

Position both cylinder halves of the new lock against the door and tighten the screws that secure the two halves together with a screwdriver.

Measure the distance between the bottom of the interior door edge and the center of the latch bolt with a measuring tape, then mark this distance on the interior of the door frame.

Position the strike plate over the mark made in Step 9. Align the place so that the mark is in the center of the strike plate opening, then trace a line around the strike plate and onto the door frame to form a rectangle.

Chisel a number of horizontal cuts, approximately 1/4 inch apart, into the outline of the strike plate with a chisel and hammer. Angle the chisel upward when making the cuts.

Chisel away the excess material within the strike plate outline by pointing the chisel downward.

Repeat Steps 11 and 12 until the strike plate rests flush against the door frame.

Bore a hole in the center of the strike plate opening within the door frame with the spade bit to accommodate the latch bolt.

Secure the strike plate to the edge of the door frame with the two retaining screws included with the lock.