How a master key system works
A master key system allows multiple locks — each with its own individual key — to also be opened by a single master key that operates all of them. The system is built around a pinning matrix: each cylinder is pinned so that its individual key works only that lock, while the master key satisfies the shear line across every cylinder in the system.
Systems can be tiered across multiple levels — a grand master key for ownership, sub-master keys for managers or superintendents, and individual keys for tenants or staff. Each tier controls exactly the doors it needs to, nothing more.
Access tiers — an example structure
Building ownership / management company
Opens every lock in the system — all units, all common areas, all service doors. Typically held by one or two people only.
Superintendent / building manager
Opens common areas, utility rooms, and mechanical spaces — but not individual residential units without authorization.
Floor managers / section leads
Opens a defined subset of doors — useful for multi-floor buildings or properties with distinct zones or departments.
Individual tenants / staff
Opens only the specific lock assigned to that person. Cannot open any other door in the system.
Who we design systems for
Multi-unit residential buildings
Co-ops, condos, and rental buildings — tiered access for management, super, and individual tenants without key proliferation.
Commercial offices
Open-plan offices, private suites, and server rooms — different access levels for executives, staff, and facilities teams.
Schools & institutions
Restricted access by floor, department, or role — with a clear hierarchy that can be updated without rekeying the entire building.
Landlords & property managers
Manage access across multiple properties or units from a single key — with individual tenant keys that can be changed independently.
Platforms we build on
We design master key systems on high-security restricted keyway platforms — preventing unauthorized key duplication and protecting the integrity of your access control over time.
- Mul-T-Lock MT5+
Triple mechanism, highest security — alpha spring + magnetic card required for duplication. - Mul-T-Lock Interactive®
Patented sidebar system, excellent key control for large systems. - Mul-T-Lock ClassicPro (MTL400)
Enhanced classic platform, reliable and cost-effective for mid-size buildings. - Mul-T-Lock Integrator
Designed specifically for master key system applications. - Medeco
Hardened steel, pick and drill resistant, available in tiered master configurations. - Schlage restricted keyways
For buildings already on Schlage hardware with upgrade requirements.