Deadbolts are generally installed on external doors and have a few more options to consider than padlocks. Deadbolts come in three primary varieties: single, double, and lockable thumbturn. Single cylinder deadbolts are found on most American homes. They use a key cylinder on the outside and a thumbturn (rosary) on the inside to open or close the lock. These deadbolts have one primary weakness.
If access to the inside is possible (via a nearby window or even through the peephole using simple tools), the door can be opened using the thumbturn. A double cylinder deadbolt uses a key cylinder on the inside and the outside of the door to solve this issue. These have the clear disadvantage of always requiring a key to open the door from the inside if it is locked. This can pose a significant problem in a fire or other emergency situation.
If used in a residential situation, it is strongly recommended that a key is left on the inside when people are present to ensure a safe exit in an emergency. The final type of deadbolt is a hybrid between a single and a double deadbolt, and is called a lockable thumbturn. It features a thumbturn on the inside that works like a normal single cylinder deadbolt, except the thumbturn can be locked using a key so it cannot lock or unlock the door. This means in a residential situation, the thumbturn can be left in an unlocked position while people are inside the house, and it will operate exactly like a standard single cylinder deadbolt. When everyone is leaving, especially for extended periods of time, the thumbturn can be easily locked so that even if someone has access to the door from the inside, the deadbolt cannot be unlocked. This type of deadbolt provides maximum flexibility and security in most situations. All deadbolts that we sell are rekeyable, however, products from some vendors are easier to rekey than others.
Jimmy proof deadbolts are a surface mount product frequently found on apartments and double doors. They are sometimes preferred due to the minimal door modifications required. They are also unique as the deadbolt interlocks with the jamb bracket preventing it from being simply pulled apart or forced easily from the outside. A surface mount lock means the lock screws into the inside of the door rather than having a complex drill pattern like a standard deadbolt. Jimmy proof deadbolts only require a hole drilled straight through the door for the rim cylinder. If you have an existing Jimmy proof deadbolt you can generally replace just the rim cylinder to upgrade your security.