Master key systems, explained.
How master key systems work, the key hierarchy, key control, what to do when a master key is lost, and when to add access control.
By Lock Raven, Maryland Locksmith License #737 · · 5 min read
How does a master key system work?
Each cylinder is pinned so more than one key can operate it: the door's own change key, plus the master keys above it. A keying schedule records which key opens which door.
What are the levels?
| Level | Opens | Typical holder |
|---|---|---|
| Grand master | Every door | Owner or facilities |
| Master | A building or area | Building manager |
| Sub-master | A floor or department | Department head |
| Change key | One door | Individual staff or tenant |
Why does key control matter?
A master key that can be copied anywhere is a building-wide risk. Restricted or patented keyways mean only an authorized locksmith can make copies, with your permission. Combined with a sign-out log, you always know who holds which key.
What if a master key is lost?
The exposure depends on the key's level. Often only the cylinders under that key need rekeying. Interchangeable cores make that faster. A well-documented system makes this a contained job rather than a rebuild.
When should access control take over?
High-traffic entrances, doors many people use, and doors where you want a record of entry are good candidates for access control, with the master key system kept for interior doors and as a mechanical override.
Need a hand with this? Talk to a licensed locksmith.
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