If you're like most people, you probably have a regular spring-latch-type lock on your door. In plain English, that's the lock on your doorknob-also known as a key-in-knob lock. The trouble with this type of lock, though, is that any burglar with a credit card can easily slip the spring and get into your home.
For this reason, many people install deadbolt locks on their doors. Deadbolt locks, unlike key-in-knob locks, are not spring-loaded and can only be opened by turning the bolt in the lock. As such, they can better withstand a break-in attempt. There are several types of deadbolt locks available, each with different advantages and features.
Types of Deadbolt Locks
Some deadbolt locks, like the latch on your doorknob, are embedded in the door itself. These slide out the side of the door and into a strike plate in the doorframe. These locks come in single-cylinder (i.e., opened from the outside with a key and from the inside with a knob or thumb turn piece) or double-cylinder (i.e., keyed both outside and inside) models.
Single and Double Cylinder Deadbolt
Single cylinder deadbolts should only be used when there's no breakable glass within 40 inches of the door; otherwise, a burglar can easily break the glass and turn the knob. If you do have glass panels in or near the door, get a double-cylinder deadbolt instead-but make sure that (a) you keep the key in a safe place (i.e., where a burglar can't reach it) and (b) you and everyone else in your household know where to find it. Otherwise, it could be a fire hazard or just plain frustrating when you're in a hurry.
Rim Deadbolt Door Locks
Other types of deadbolts, called rim deadbolt locks, are mounted on the outer surface of the door rather than inside it. A regular rim deadbolt slides into a strike that you mount on the doorframe inside the house, and opens with either a knob or a key.
Interlocking rim deadbolts, which, as the name suggests, interlock with the strike on the doorframe via a vertical deadbolt, are especially secure because they resist jimmying.
Coded Deabolt Door Lock
In this modern day and age, of course, you can also find coded deadbolts with pushbutton or digital keypads and electronic remote controls. These latter designs are more expensive, but they're more convenient for senior citizens or disabled users who may find it difficult to get to the door.
Installation and Security Tips for Deadbolt Locks
Before you install a deadbolt, make sure you're getting optimal security out of it. A quality deadbolt should protrude at least 1" from the door edge when thrown-and since your deadbolt is only as strong as the door it's attached to and the screws you attach it with, it'll be most effective if mounted with carriage bolts on a door with a solid wood core.
For the strike, use 2"-3 ½" screws-they're harder to break than the ¾" ones that come with the lock. To install a standard deadbolt lock, use the template that comes with it to line up the lock on the door, and mark spots for the holes with an awl. Then, cut a hole through the door for the cylinder and drill a hole through the door edge to accommodate the bolt.
Next, fit the cylinder and bolt into the holes, chisel room for the faceplate on the door edge so it doesn't protrude, and fit the faceplate over the bolt. Drill holes for the screws, and screw the lock in place.
Finally, line up the strike on the doorframe, drill holes for the bolt and the screws, and screw in the strike plate. If you're installing a rim deadbolt, just line up the lock on the door with the template, mark the relevant cutting and drilling spots, and cut a hole for the cylinder (you don't need an extra hole for the bolt). Fit the lock into the door, drill the screw holes, and screw it in place. Then, line up the strike on the doorframe, mark and drill screw holes, and screw that in place, as well.
While even a strong deadbolt won't prevent a burglary, it'll go a long way toward making your home more secure.