A master key system sounds complicated and is not. Each cylinder simply accepts two keys instead of one. However, the design decides whether it still works in five years.
How it actually works
Each cylinder carries an extra set of pins, creating a second combination that also opens it. Consequently your key opens your door and the master opens every door. Furthermore, layers can be added: a floor master, then a grand master above it. Therefore the structure mirrors how the building is actually used.
Design before cutting anything
Map who needs access to what, then decide how many levels you need. Consequently the chart comes before the hardware. Moreover a system built without spare combinations must be rebuilt entirely when you add a door, which is the single most common and expensive mistake.
Pair it with restricted keys
A master system on standard cylinders can be undone by one trip to a hardware counter. Consequently restricted blanks matter more here than anywhere. Therefore every copy requires authorisation, and the master itself cannot be quietly duplicated.
Living with it
Number every key and record it against a holder. Consequently a departing employee becomes a retired key rather than a building rekey. Additionally an annual audit against the list takes minutes. Above all, keep the chart somewhere findable, because rebuilding one from a site survey is slow work.
Questions we get about this
How many levels can it have?
Several. However, most small buildings need two or three.
What if the master is lost?
Serious, because it opens everything. Consequently restricted keyways limit the risk.
Can we add doors later?
Yes, if the chart left headroom. Therefore we always allow for it.
Will it work with our existing locks?
Sometimes, if keyways match. Otherwise cylinders get swapped.
