A master key system lets one key open many doors while each door keeps its own individual key. Done properly it is a genuine operational improvement. Done badly — and it frequently is — it produces a system that cannot be expanded, that has unintended cross-keying where keys open doors they should not, and that quietly stops being secure the moment one key goes missing.
Typical range: $350–$6500 CAD. Ranges are typical for the GTA and depend on the door, the hardware and the time of day. We confirm the price before dispatching.
How a system is structured
The basic hierarchy runs from the change key at the bottom, which opens one door, through a master key that opens a defined group, to a grand master over several groups. Large sites can add a great grand master above that. The design work is deciding which doors group together, and it should follow how the organisation actually operates rather than how the floor plan is drawn.
The technical constraint people do not anticipate is that every level of mastering consumes some of the available differs — the total number of distinct keys the keyway can support. A system designed without headroom works perfectly on day one and cannot accommodate the new suite you take over in year three. We design in expansion capacity from the start, because retrofitting it means rekeying everything.
The cross-keying problem
When a cylinder is pinned to accept both its own key and a master, it gains extra shear points. Add enough master levels and you create combinations that were never intended — keys that open doors they were never issued for. This is called an unintended cross-key, and in a sloppily designed system it is not rare.
Avoiding it is a matter of disciplined arithmetic at the design stage. It is the main reason a master key system should be laid out on paper as a complete plan before a single cylinder is pinned, rather than grown door by door as needs arise.
Restricted keyways and why they matter
A standard keyway can be duplicated at any hardware store or kiosk. That means your master key system is only as controlled as the most casual employee who has ever held a key, and you have no way to know how many copies exist.
A restricted keyway uses a key blank that is not sold on the open market and is protected by patent, so duplication requires going back to the authorised dealer and presenting documented authorisation. This is what makes key control real rather than notional. For any system where a lost master would mean rekeying a building, it is the correct specification.
Documentation and key control
We supply every system with a full keying schedule: which cylinder carries which combination, which keys exist, and who holds them. Without that record, future work on the system becomes guesswork and the system degrades over time.
We also set up a key issuance record so you can answer the question that matters after a departure or an incident: exactly which doors does this person's key open, and has it come back.
Frequently Asked Questions
What happens if a master key is lost?
How bad this is depends entirely on the keyway. On a restricted system, a lost key cannot easily be copied, so you have time to respond in a measured way — reissue at the affected level rather than rekeying the site. On an open keyway you have to assume copies could be made, and the prudent response is rekeying every cylinder the lost key operated. This difference is the strongest practical argument for restricted keyways on any system of consequence.
Can you add doors to a master key system we already have?
Usually yes, provided the original system had expansion headroom and we can identify the keyway and the existing combinations. If the original keying schedule exists, that makes it straightforward. If it does not, we can decode the existing cylinders and reconstruct the schedule, which takes longer but is entirely doable.
Is a master key system less secure than individual keys?
A well-designed one is not meaningfully less secure, and the operational control it provides usually improves overall security. A poorly designed one genuinely is less secure, because excessive master levels create extra shear points and unintended cross-keying. The variable is design quality, not the concept.
How long does it take to set up?
Design and consultation for a typical commercial site is usually a matter of days, and installation depends on the number of cylinders. A small office of ten to fifteen doors is generally a single visit once the cylinders are pinned. A multi-building site is scheduled in phases so you are never without access.
Master Key Systems across the GTA
We provide master key systems throughout the Greater Toronto Area. Pick your city for local detail, or call and we will tell you straight away whether you are in range.
Related services
High-Security Locks
Pick-, drill- and bump-resistant cylinders on patented restricted keyways, for doors where a standard cylinder is not adequate.
Lock Rekeying
Existing cylinders re-pinned to a new key — the fast, inexpensive answer to staff turnover, lost keys and taking over premises.
Access Control Systems
Card, fob, mobile and biometric access control designed, installed and commissioned — on platforms you own rather than are locked into.
Commercial Door Repair
Doors that bind, drag, sag, will not latch or will not close — diagnosed at the door and frame rather than blamed on the lock.