What This Article Covers and Who It Helps
If you manage a residential apartment building, are a contractor bidding a multi-family project, or are an architect writing a hardware schedule for a new mid-rise, maison keying is one of the first decisions you need to get right. This article explains what maison keying is, how it differs from a standard master key system, and what it means for your cylinder selection, hardware schedule, and building entrance hardware.
What Is Maison Keying?
Maison keying is a two-tier key system used almost exclusively in multi-unit residential buildings. Every tenant carries a single key that does two things:
- Opens all common-area locks in the building (main entrance, laundry room, mailroom, parking garage, amenity doors)
- Opens only that tenant's individual unit door
No tenant key opens a neighbor's unit. Management typically holds a separate master key (or grand master) that opens every door in the building, including all unit doors.
The name comes from the French word for house and reflects the system's origins in European multi-family housing. In North America it is the de facto standard for apartment buildings, condominiums, and mixed-use residential towers.
How Maison Keying Differs from a Standard Master Key System
In a typical commercial master key system, change keys open one lock and the master key opens all of them. Maison keying inverts part of this logic:
- The tenant key acts like a limited master for common-area locks -- it is shared across many tenants, all carrying the same common-area bitting
- Each tenant key also has a unique bitting for the unit cylinder that no other tenant key can operate
- Common-area cylinders are pinned to accept both the tenant common key and the building master key
- Unit cylinders are pinned to accept the specific tenant change key and the building master key, but not other tenant keys
This is accomplished through master pins in each cylinder chamber, creating two shear lines -- one for the common key, one for the individual tenant bitting or master key bitting.
Why Maison Keying Is the Right Choice for Apartment Buildings
- Tenant convenience: One key on the ring. No fumbling for a separate building key and a unit key.
- Controlled access: A lost or stolen tenant key does not compromise other units -- only the common areas, which can be rekeyed independently.
- Management control: The building master or grand master key opens everything without having to carry 80 tenant keys.
- Code alignment: Many jurisdictions -- including New York City under its Administrative Code and Multiple Dwelling Law -- specifically address building entrance lock requirements for Group R-2 occupancies, including stopwork provisions in inside cylinders controlled by a master key only.
Cylinder Selection Matters More Than People Think
Maison systems require more master pins per cylinder than a simple two-level commercial system. That additional complexity narrows the number of unique combinations the factory can produce and slightly reduces pick resistance. The cylinder quality you specify directly affects how well the system holds up over time.
What to Look For in a Maison Cylinder
- Grade 1 rated cylinders for building entrances and high-traffic common doors
- Mortise cylinders where the entrance lock is a mortise-style heavy-duty lockset (standard for apartment main entrance doors in most codes)
- Interchangeable Core (IC) format for buildings with frequent tenant turnover -- IC allows rekeying a unit door in minutes with a control key, no tools or locksmith required
- Restricted keyways where key control is a priority -- patented keyways prevent unauthorized duplication at the hardware store
Brands such as Sargent, Corbin Russwin, and PDQ offer mortise cylinders and IC cores well-suited to maison systems. Their multiplex keyway families give a keying engineer the combination depth needed to support a large building without running out of unique unit bittings.
Building Entrance Hardware and Maison Key Compatibility
The building entrance lockset is the anchor of the entire maison system. In most multi-family applications this is a heavy-duty mortise lock on the main entrance, often paired with an intercom or access control release. The outside cylinder must accept the tenant common key; the inside should have stopwork or a passage function so tenants can exit freely without a key.
If the building uses an electrified release at the entrance -- an electric strike or electrified latch -- the keyed cylinder still needs to be part of the maison system for manual override access. Confirm that your cylinder cam or tailpiece is compatible with the lock body before the hardware schedule is finalized.
Common Openings in a Maison Key Plan
- Main entrance door (mortise lock, heavy-duty, maison keyed outside cylinder)
- Secondary vestibule or garage entrance (maison keyed)
- Laundry, mailroom, amenity spaces (maison keyed)
- Individual unit entry doors (change key for that tenant plus building master)
- Management office and mechanical rooms (typically on a separate restricted master key, not part of the tenant maison level)
Keying Schedule Documentation: Don't Skip This Step
A maison system for even a 20-unit building requires a written keying schedule submitted to the factory. The schedule defines:
- Which cylinders are common-area (maison keyed alike)
- Which cylinders are unit doors (each on its own change key)
- The master key level that opens everything
- Key quantities, key tags, and any construction master requirements
Errors in the keying schedule are expensive -- they mean cylinders must be pulled, re-pinned, or replaced. Get the schedule reviewed before it goes to the factory.
Ready to Spec a Maison System for Your Building?
DoorwaysPlus.com carries mortise cylinders, IC cores, and building entrance hardware from preferred lines suited to multi-family maison keying projects. Whether you are writing a hardware schedule for a new build or re-keying an existing apartment community, our team can help you work through the keying plan, cylinder selection, and entrance hardware compatibility before you commit to an order.