A security door is built to help prevent unauthorized entry from intruders; it also can help withstand the force from storms and weather abuse, and can offer a much higher level of protection than a regular door. Security doors typically come in two basic types. One type is an openwork steel door, which looks like wrought iron and has a tempered glass back panel. The second type looks like a regular wooden or fiberglass door, but is actually made of steel with sturdy side fixings. A security screen door can be added for an additional level of safety. A security door does not have to be only external; for example, they can be used to protect panic rooms, escape routes, basements or vaults.
Aside from the materials used to construct the security door, many devices can be installed which add to the level of safety it will provide. These can include deadbolts, bars, alarms and door chains. A door viewer, or peephole, can be used, which is a small lens that allows the user to see the person on the other side. Hinge screws can also be installed, which are long screws that keep the door from being pushed in if the hinge pins have been removed. On a high-security door, the hinges are typically hidden from view, which can make it much more difficult for intruders to get inside. A high-security strike plate may also be considered, as the strike plate is usually the weakest part of a door system.
Lock quality is extremely important when considering a door for security purposes. A good lock may be enough of a deterrent that it can cause a would-be burglar to try a different target. A poorly made lock can easily be drilled, pried or hammered off. In the United States, The American National Standards Institute (ANSI) has developed standards that help to classify the quality of locks. They label the highest quality locks as ANSI Grade 1.
Locks with key control can be an asset to a security door. These locks come with special keys that can usually only be copied by their manufacturer. This helps prevent anyone else from obtaining a copy of the key without the owner's permission. Keyless locks are also available, which eliminate the need for keys. A keyless lock can use a numeric code for entry, which can be changed as often as needed. A fingerprint lock is also an option, which uses a person's fingerprint as a key. This type of lock can be very expensive, but due to the uniqueness of fingerprints, it can also be very secure. Double cylinder deadbolts with keyholes can also be placed on both sides of the door, as this can help stop burglars from simply breaking a glass window, reaching in, and unlocking the door.