Master Key Systems for Businesses in Phoenix

A master key system lets different people carry different keys and still open exactly the doors they should. A tenant’s key opens one suite. A floor manager’s key opens every suite on that floor. The property manager’s key opens them all. Each lock is built so that more than one key can open it, and how well the system works depends on how that was planned and recorded.

We set up and rekey master key systems for offices, multi-tenant buildings and other commercial sites around Phoenix. This page explains the key levels, the keying schedule, why real key control comes from the keyway and not from a stamp, where badly designed systems go wrong, and what we need to see before we quote.

The levels, in plain English

Every system is built from the same few layers. Manufacturers and locksmiths use slightly different names, and some call a middle layer a submaster, so what matters is who opens what.

Worked example: a small office

Take an office with eight locked doors: the front door, back door, supply room, server closet, the owner’s office, two manager offices and the accounting office. Two levels are enough.

• Everyday key. The front door, back door and supply room are keyed alike. Staff carry one key, and it opens only those three doors.
• Manager keys. Each manager’s key opens that manager’s own office. They also carry the everyday key. They cannot open each other’s offices, the accounting office or the server closet.
• Named keys. The accounting office and the server closet each have a key that is issued by name, to the people who need it.
• Owner’s master key. Opens all eight doors.

The point of the design is containment. A lost everyday key means rekeying three locks. A lost manager key means one office. Only the owner’s master touches everything, so that is the key you track most closely.

Worked example: a multi-tenant building

Now take a three-story building with twelve suites, a shared lobby, a mechanical room and a roof hatch. This is where the levels earn their place.

• Change key: each suite. The tenant in Suite 204 gets a key that opens Suite 204 and nothing else.
• Master key: each floor. A floor master opens the four suites on one floor. It suits an on-site manager or a contractor who should be limited to that floor.
• Grand master key: the property manager. Opens every suite on every floor, plus the mechanical room.
• Great grand master key: only if needed. It sits above several grand master groups, for example when a property has more than one building, each with its own grand master. A single building rarely needs one.

Shared doors need a decision. Either every tenant’s key also opens the lobby, which is called maison keying and creates an extra way into that lock, or the lobby runs on a separate common-area key or a card reader. We would raise the second option first. See access control systems for card readers. If the building has a rapid-entry key box for the fire department, tell us, because the keys inside need to be updated when the system changes.

How it works inside the lock

A normal cylinder has one position where all the pins line up and the lock can turn. That position is called the shear line. Master keying adds extra pieces to the pin stacks so there are two or more positions where the lock will turn, one for each key level that must open it.

That is why a master key system is designed on paper first. Each additional key that opens a lock is another way into it, and the combinations can produce keys nobody planned, called phantom keys. A well-designed system is checked for these before any key is cut, and checked again whenever the system grows.

The keying schedule and key records

The keying schedule is the plan for the whole system. It lists every door, every key level, which keys open which doors and who is meant to hold each key. Three related records matter.

• Door schedule. Every door, its location, who needs access and how sensitive the space is.
• Bitting list. The cut numbers for every key and lock. It is what lets a locksmith add a lock or make a key later and have it fit the system.
• Key issue log. A signed record of who holds each key and when it went out and came back. The commercial rekey page covers it in more detail.

Without these records, adding a tenant or a building later can force a bigger rekey than the job needs, sometimes of the whole system, because nobody can tell which combinations are already in use. Ask us what we can hand over at the end of the job. Treat the schedule like a key: whoever holds it can have keys made.

MACS: the limit every key has to respect

MACS stands for maximum adjacent cut specification. It is the largest difference allowed between two neighboring cuts on a key. If a key breaks the limit, it may not go into the lock or may not come back out. The limit differs by manufacturer and by keyway. If a keyway allows no more than five steps between neighboring cuts, a very deep cut beside a very shallow one is not allowed.

A master key system multiplies the keys that have to be checked, because every change key, master and grand master must be cuttable and must work. A design that ignores the limit looks fine on paper and produces keys that jam. A well-built system checks each key against the limit for its keyway, follows the manufacturer’s pinning method and is screened for phantom keys. Bigger systems call for software. If you already have a system, tell us what records you hold and we will look at what you have.

Restricted keyways and what key control really means

Key control is the ability to decide who can get a copy of a key. In practice it comes from three layers working together.

1. A restricted keyway. Standard keyways use blanks sold everywhere. A restricted keyway uses blanks the manufacturer releases only through approved channels, so an ordinary key shop usually cannot get blanks for it. Patented keyways add legal protection for as long as the patent lasts. Schlage (Everest and Primus) and Medeco are examples of makers with restricted and patented lines.
2. A named list and a paper trail. Only people on your list can order keys, and every key issued is signed for. Restricted programs from manufacturers commonly tie ordering to a key card or a customer record.
3. Features inside the cylinder. Sidebars, check pins and similar parts make casual copying and picking harder.

Restricted keys are controlled by the manufacturer, and ordering usually requires an authorization card or customer record, so allow lead time. Ask us early whether we can order for the keyway you want.

Where poorly designed systems go wrong

• Too many levels. Each level adds ways in and uses up key combinations.
• Locks added one at a time. A lock keyed on the spot without checking the schedule can open with keys it was never meant to accept, or use up combinations the next lock needed.
• Cross-keying and maison keying. Cross-keying lets specific change keys from different groups open a shared space. Maison keying lets every apartment key open the main entrance. Both are convenient, and both add another way into those locks.
• No records. Nobody knows who holds what, so one missing key becomes a building-wide question.
• One master key for everything. If it is lost, the answer is a rekey of the whole system.
• Ignoring MACS. Keys cut outside the limit can stick or jam.

Plan for growth

The easiest time to plan for expansion is the first design. A system built with room to grow lets you add a suite, a department or a building without touching the locks already in service. That means reserving unused combinations, grouping keys by floor, wing or department so the groups match how you actually run the place, choosing a keyway family that will still be available later, and keeping the bitting list current. Master keying uses up combinations quickly. Tell us the changes you can see coming, such as new tenants, a second building or a split department, so the plan can allow for them.

If a master key is lost

The response depends on the level of the key.

• Change key. Rekey that lock or small group. Nothing else is affected.
• Master key. Treat it as lost for every lock it opens. The usual answer is to rekey that group and issue a new master.
• Grand master or top key. The whole system is exposed. The usual response is to rekey every lock the key opens, which is why top-level keys should be few, numbered and signed for.

Write down which doors the key opens and when it was last seen, find your keying schedule, stop issuing copies, and call us. Where it was lost and who could have it decide how urgent the rekey is. Systems built on interchangeable cores can be quicker to recover when spare cores are on hand, because cores can be swapped without opening the lock. We explain that on our IC core locks page. For smaller systems on conventional cylinders, see commercial rekey. We do not promise timing on a large rekey, since some parts may need to be ordered.

Who needs a master key system

Schools and clinics set their own rules for vendors on site. Tell us what they are when you call and we will say whether we can meet them. If you are planning a school system, our school door security checklist is a useful place to start.

For a project this size we look at the doors first and agree on the price before any work starts. The commercial quote page collects the details, or you can call (602) 301-5243. A very large multi-building system may not suit one technician, and we will say so before you commit. Everything else we do for businesses is listed on our commercial locksmith page.

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