The level of security a lockset offers depends on its construction. Any type with only a key in the knob or handle is only marginally secure; a burglar can easily foil it. For more security, a deadbolt should be installed with at least a one-inch throw-which means it should extend a minimum of one inch beyond the door's edge and be made of case-hardened steel.

The key to getting the most out of your visit from a locksmith is understanding the different types of locks that you need to install or repair ahead of time.

Exterior entry locksets have a large, rectangular body that slides into a mortise (a cavity carved into the edge of the door made to receive the lock mechanism).

Mortise locksets contain the workings for the knob, lever, or grip handle, latch, and deadbolt in a single unit. With a mortise set, the knob generally is interconnected with a security deadbolt. Mounting a mortise lockset calls for fairly tricky carpentry work.

Cylinder locksets have a rounded body designed to fit into intersecting holes bored into the door. The deadbolt bar, which slides into a corresponding opening in the doorjamb, is the main source of your security.

Rim locks, or surface deadbolts, are the deadbolts that are independent of the doorknob. Installed in the inside of the door, the bolt fits into a corresponding sleeve attached to the inside door frame.

The basic padlock, a familiar sight on gates, lock doors and even luggage zippers, is a portable key-operated lock built around a steel loop that clicks into the lock's body.

Double-cylinder deadbolts require the use of a key from both sides of the door. This is the safest type to use for doors with windows. For better security, a knob, lever or grip handle should be paired with a deadbolt.

Door Lock Repair

With time and temperature shifts, houses settle and move up and down. This can dramatically affect how a latch or deadbolt matches up with the hole on the doorframe. This can be a simple do-it-yourself project. Simply file the hole bigger.

If your door knobs or handles were installed after 1960, they probably have standardized hardware, so replacing the damaged hardware is easier and less expensive. For doors installed before 1960, it may be worth it to try to repair the hardware, especially with old antique doors.