Key Systems And Restricted Keys

The lock on a common door is only as good as the control over who has a key to it.

In a building where keys have been cut freely at a hardware counter for twenty years, nobody knows how many exist or who holds them. The locks are fine and the security is gone.

What a restricted system is

A key profile that is patented and can only be cut by an authorised locksmith, against an authorisation list held for that building.

Which means a key cannot be copied at a shopping centre kiosk, and every key issued is recorded against a person.

The value is the record as much as the restriction. When a caretaker leaves or a contractor finishes, you know exactly what they hold.

Master keying

A properly designed system lets one key open a defined set of doors while other keys open only their own.

A resident's key opens the front entry, their floor and their apartment. A building manager's key opens common areas. A contractor's key opens a plant room and nothing else. The committee holds a grand master.

Designing that hierarchy is the part that needs thought, and it is worth doing once properly rather than adding doors to a system that was never planned.

When to rekey

A key is lost and cannot be accounted for, particularly a master.

A caretaker, building manager or contractor with access leaves, and the keys do not all come back.

The system has drifted, with mismatched locks added over years so half the doors are on one profile and half on another.

The patent has expired, which is the one nobody tracks. Key profile patents run for a limited term, and once expired the profile can legally be cut by anyone. A restricted system whose patent lapsed a decade ago is restricted in name only.

The cost conversation

Rekeying a building is not cheap. The locks, the cylinders, the keys and the administration all add up, and in a large building it is a significant item.

The comparison is not against zero, it is against the cost of a break-in through a door that opened with a key, and against the insurance position when that happens.

A staged approach works where the budget will not carry it in one go: common entry and plant rooms first, apartment doors as they turn over.

Running it properly afterwards

A key register that is actually maintained. Keys issued against a signature. A deposit that gets returned when the key does. A defined process for a lost key that does not depend on someone remembering.

Buildings that do this keep their system working for a decade. Buildings that do not are back to unknown keys within three years, and the money spent on the rekey is wasted.

Mechanical and electronic together

Electronic access solves the auditing problem completely: a fob is deactivated in seconds and every entry is logged.

Most buildings end up with both, because fire stairs, plant rooms and apartment doors stay mechanical while entries and lifts go electronic. That mix is normal and it needs to be planned rather than assembled, which is the same point made in [intercom and access control upgrades](/blog/intercom-and-access-control-upgrades).

Ample handles locksmithing alongside the door hardware, the closers and the fire door compliance, because a key job in an older building is almost never only a key job.