Adding extra security to your home by installing a deadbolt is an easy, inexpensive project that can be done in less than a day. Deadbolts come in several different finishes so you should be able to find one that matches or comes very close to your existing hardware finish.
Deadbolts can be purchased as keyed on both sides or keyed on the outside and a thumbturn latch on the other inside. The latter being the most common for residential use.You will need a 2 1/8 "hole saw that fits into a drill to make the hole needed for the new deadbolt, as well as a 7/8" wood boring bit that makes the Hole for the striker latch. These are also commonly known as "spade" bits or "butterfly" bits. They can be found at any home improvement store for about $ 20 combined.
The first thing you will want to do when you have your deadbolt is locate where you want to place it on the door. Usually they are just above the existing door knob, about six inches center to center but you can go slightly more or less to suit your set up or if there is a window in the door that will interfere. Make sure the deadbolt will not interfere with the storm door handle if you have one. Most of the time, it does not stick out far enough to cause a problem.
Measure in from the edge of the door whatever the "setback" is on the existing knob. The setback is the distance from the edge of the door to the centerline of the door knob or deadbolt. This is usually 2 3/4 "Older doors can be 2 3/8". Carry the line across to the edge of the door and mark a line across the edge. Start drilling your 2 1/8 "hole with the hole saw going slowly to begin. If you have a metal door, you may want to drill a pilot hole first and drill at a slower speed when making the 2 1/8" hole.
Once you are through the metal skin, keep going through the wood core and partly through the other side with the guide bit. Finish by drilling from the other side so as not to make a rough edge by drilling it all from one side. Measure the centerline on the edge of the door where you transported the line across earlier. This is where you will use the 7/8 "bit and drill through until you get to the larger hole. Place the latch into this hole and trace the outline of the face plate. Chisel out this area the depth of the face plate thickness with A 1/2 "or 3/4" chisel.
You are now ready to install the new deadbolt. Place the latch in first and then the deadbolt. It may be necessary to partially extend the bolt to line up the screw holes and guide pin when placing the two sides together. Once together, insert the screws and do not tighten just yet. Put the screws in the latch and tighten those, then go back and finish tightening the other screws. Complete the process by locating the position of the strike plate on the door jamb. Do this by extending the bolt against the jamb and marking with a pencil the top and bottom of the bolt.
Measure the distance from inside of the bolt to the edge of the door and mark that distance on the door jamb. This along with the two lines made previously, is the hole location for the deadbolt. Drill a 3/4 "hole just through the jamb and finish by tracing the outline of the strike plate and chiseling out the thickness of the plate. Fit the strike plate in and pre-drill two 1/8" holes for the screws and insert The long screws so they reach the framing of the door. You have now installed added security and peace of mind to your home without having spent a fortune.