Vaults and strongrooms

A bank vault or strongroom is a reinforced room or compartment in a bank building where valuables are stored. Modern bank vaults generally contain many safe deposit boxes, as well as places for teller cash drawers, and other valuable assets of the bank or its customers. Vaults are also common in other buildings where valuables are kept such as post offices, grand hotels, and certain government ministries.

Historic bank vault from 1901.One of the more important functions of a bank vault, just as for large bank buildings, is to give customers the feeling that their money and valuables are secure. The largest bank vault door known in the world is that of Federal Reserve Bank of Cleveland. This door has an overall height of 574 cm (226 inches) and weighs over 42 metric tons (47 short tons) fully assembled. The door casting itself was 18160 kg (20 tons). It incorporated the largest hinge ever built. Banks struggle to demonstrate similar security in the era of electronic funds transfer, although it is likely just as impervious as the large vaults and buildings of yesteryear.

Historically, strongrooms were built in the basement of the bank where the ceilings were vaulted. They are now typically built primarily of thick steel-reinforced concrete, although steel plates are sometimes incorporated into the walls, floors and ceiling to slow down would-be safe-crackers who may attempt to tunnel into the vault. Vibration and sound detectors accumulate sounds and set off an alarm if a lot of noise is made over a period of hours. These measures defeat most robbers who would tunnel into the vault from beneath or through a wall.

Banks' vaults are now almost all locked with a timed lock, to prevent thieves from taking the manager as a hostage during a robbery and bringing him back to unlock the vault late at night, which used to be a problem.