People often install sturdy locks on their front doors but leave sliding glass doors and sliding glass windows "wide open" to illegal entry. Burglars look for both of these because they are easy to open. Usually, sliding glass doors and windows are more secluded than a front door, making a perfect place for burglars to hide and enter. Two factors must be protected against.
Prying the Lock
Most sliding glass doors and sliding windows come equipped with a lock that is easily pried open. A supplemental lock must be installed. Broomsticks (they should fit snug), "Charlie bars" and finger operated locks provide some protection.
Key locking devices are much preferred because they can prevent the burglars from using the door or window to remove stolen property. There are several types of supplemental locks available. Keyed locks may be keyed alike with other entry lock sets and deadbolts. Check with your locksmith or hardware store and select a sturdy type that most suits your home.
Many sliding glass doors and sliding windows can be lifted out of their tracks from the outside. 2 sheet metal screws placed in the track above the removable part of the door or window can prevent it from being removed. Adjust the screws so that the doors or window will just clear underneath them. Drill a hole and insert a nail through the inside frame and part way through the metal door frame. You can remove the nail but the burglar can't.