When choosing a lock to protect your home from unauthorized entry, a deadbolt lock will usually be the best choice. In fact, building codes and fire code regulations in many areas require the use of a deadbolt lock on all doors that provide entry into a home. A deadbolt lock works by moving a bolt in or out of the lock assembly and door frame. These types of locks differ from various other types in that they are not spring-loaded and are much harder to defeat.
Deadbolt locks usually come in two varieties—single or double cylinder deadbolt.
The single cylinder deadbolts design includes a keyed entry from the outside and a thumb knob/latch on the inside. A double cylinder deadbolt requires that the key be inserted in order to open the lock from either side. Regardless of the type of deadbolt lock you purchase, there are certain things you should always look for in order to purchase a deadbolt lock that provides adequate security and peace of mind.
1. ANSI Grade Lower Than 1
The American National Standards Institute (ANSI) is a nonprofit group that is responsible for developing standards in many industries, including the manufacture of deadbolt locks. A deadbolt lock that has been rated grade 1 has been tested with at least 250,000 open/close cycles and has a bolt that is inserted at least one inch into the door frame. Also, a grade 1 deadbolt lock can withstand a minimum of 10 hammer blows before giving way. Never purchase a deadbolt lock that does not have an ANSI grade 1 rating and always avoid cheap imported locks that have no ANSI rating at all.
2. Double Cylinder Locks
You should avoid double cylinder deadbolt locks as much as possible. In fact, the only time you should ever consider using a deadbolt lock that requires a key to open the lock from either side is when the lock can be reached from a nearby window. In an emergency, using a double cylinder lock may make it difficult for you to exit your home.
3. Not UL 437 Listed
Underwriters Laboratory is another very well known and respected organization that tests various types of products and develops standards for them. Underwriters Laboratories’ UL 437 rating is the standard for high-security deadbolt locks and is accepted in all sectors of the security industry. In order for a deadbolt lot to meet UL 437 standards, the lock must be able to resist various types of attacks, such as: drilling, picking, prying and hammer attacks. So, always look for the underwriter's UL 437 rating on any deadbolt lock you purchase.
4. Short Strike Plate Screws
Whenever purchasing a deadbolt lock, never purchase one that uses screws less than three inches in length. Longer screws that are used to attach the strike plate of the lock will allow you to insert the screws not only into the doorjamb, but into the door frame as well. The door frame is significantly stronger than the doorjamb and will further increase resistance and door strength should someone try to push through the door.