What is a master key system, and does your Mission Hills building need one?
A master key system is a planned arrangement of locks and keys in which each person carries one key that opens only the doors they are supposed to open, while a higher-level key opens a wider group. A tenant's key opens their own unit. A property manager's key opens every unit. A single top key held by the owner opens everything. Nobody carries a ring of fifteen keys, and nobody holds a key that opens more than their job requires.
You do not need one because a building is large. You need one when the number of doors, the number of people, or the turnover of those people has outgrown the key ring in someone's pocket. That might be a small office with a back storeroom, a clinic with staff and cleaners on different schedules, or an apartment building with a dozen units and shared laundry and trash rooms. If you have ever said, I am not sure who still has a key to that door, you are already describing the problem a key system solves.
This page covers the planning and installation of those systems: commercial master key systems, apartment master key systems, restricted keyways, and duplicate-protected keys. If what you actually need is a single lock changed, we will say so and point you to the simpler service.
The real problem: key sprawl and no record of who can open what
Most buildings do not start with a bad key setup. They get there slowly. A tenant leaves and the lock is never changed. A contractor is handed a key for a week and it is copied at a hardware store. A manager quits and nobody can say whether the keys came back. Ten years later the building runs on a mix of lock brands, a drawer of unmarked keys, and the hope that nothing goes wrong.
The trouble with that is not just security. It is accountability. When a storeroom is opened after hours and ten people could have done it, you learn nothing. When a door is left unlocked and four keys fit it, nobody owns the mistake. A proper key control system gives every key a purpose, a holder, and a record, so the answer to who can get into this room is a short list you can read out loud.
The other common situation is growth. A business adds a second suite, a landlord buys a second building, or an office starts to hire. Rekeying everything to match is usually the right move, and a master key system is how you do it once instead of redoing it every time something changes.
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Call (213) 577-1366How a master key hierarchy works
Inside a pin-tumbler cylinder, a key lifts spring-loaded pin stacks until a gap lines up at the shear line and the plug turns. A master-keyed cylinder is built with an extra pin layer so that two different keys can create a valid shear line: the individual key and the master. That is the whole mechanism. The planning around it is where the skill lies.
A typical hierarchy has several levels, and you only use as many as you need:
- Change key (or individual key): opens one door or one group of identical locks, such as a single tenant's unit or one employee's office.
- Master key: opens a defined group, such as every unit on one floor, every office in one department, or all the suites a property manager oversees.
- Grand master key: opens several master groups, typically held by an owner, a facility head, or a small number of trusted people.
- Great grand master (rare): a fourth level used only in large, multi-building arrangements.
- Control or service keys: specialty keys that remove a removable core, used when the system is built on interchangeable cores.
Restricted keyways and duplicate-protected keys: control over who can copy
A hierarchy decides who can open what. A restricted keyway decides who can make more keys. On a standard, open keyway, any hardware store or kiosk with a blank can copy your key in a minute. On a restricted keyway, the key blank itself is controlled. The profile is protected by the manufacturer, blanks are not sold over the counter, and copies are made only through authorized channels with the right paperwork.
Duplicate-protected keys build on this. Those keys are stamped as not to be copied, but the stamp alone is just a request; the real protection is the restricted blank behind it. When we set up a restricted key system, we can arrange it so that new keys require authorization from a named person on your account. That is what makes an employee key control system actually work: a key can be handed back at the end of a job, and you know no copies are floating around.
Restricted keyways are a form of high-security hardware, and some systems also add features such as hardened pins or drill resistance. If you want to look at that side of things, we cover it on our high security locks page. For ordinary, unrestricted keys, the simpler key duplication service applies.
How we plan and install a master key system, step by step
The order matters. Systems that go wrong usually skipped the first two steps and jumped straight to cutting keys. This is how we work, and David reviews the plan before any cylinders are ordered.
- Walk the property and count doors. We list every lock that needs to be on the system: entry doors, suite doors, storerooms, utility rooms, gates, and cabinets. We note the existing hardware, its condition, and whether each door can take a standard cylinder.
- Decide who needs access to what. This is a conversation, not a form. We ask who opens which doors on which days, who holds keys today, and who should not hold keys at all.
- Draw the hierarchy. We lay out the levels, assign each door to a group, and prepare a keying chart. The chart is the master record for the whole system and you keep a copy.
- Choose the keyway and key control level. You pick between an open keyway, a restricted keyway, or a restricted keyway with duplicate protection, based on how tightly you want copying controlled.
- Order and build the cylinders. Cylinders are pinned or core-keyed to the chart. Pinning mistakes are what cause a wrong key to open a wrong door, so we check every cylinder against the chart before it goes in.
- Install, test every key on every door, and tag. Each key is tried on each lock it should open and on each lock it should not. Then keys are labeled by code, not by door name, so a lost key does not announce which building it belongs to.
- Hand over the records. You get the chart, the key issue log format, and a plain explanation of how to authorize new keys later.
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Call (213) 577-1366What affects the cost of a master key system?
We do not quote numbers on a web page because a system with six doors and a system with sixty are different jobs, and a price without a door count would be a guess. What we can tell you is what moves the cost up or down, so you can plan.
- Number of doors and cylinders. Every lock on the system needs a cylinder pinned to the chart. More doors means more hardware and more labor.
- Number of levels. A two-level system is simpler than a four-level one. More levels mean more planning and more keys to cut.
- Open versus restricted keyway. Restricted blanks and authorization paperwork cost more than standard keys, but they are what stops unauthorized copies.
- Existing hardware. If your current locks can be re-pinned to the new system, it is usually the more economical route. If they are worn, mismatched, or not built to accept the extra pin layer, those locks need replacement.
- Rekey versus new cylinders. Converting existing cylinders with a master key rekey is generally lighter on cost than replacing hardware, as long as the locks are in good shape.
- Removable-core cylinders. These cost more up front but make future key changes faster, which matters if you expect frequent turnover.
- Number of keys issued. Each key costs something to produce, and restricted keys cost more than standard ones.
- Related door work. If a door also needs a closer, panic hardware, or an adjustment before the lock will work properly, that is a separate line on the job.
Master key systems in Mission Hills: apartments, offices, and shared doors
Mission Hills has a mixed building stock, and that shapes which kind of system makes sense. The housing is mostly 1950s single-family ranch tracts on modest lots, and a single-family home does not need a master system. Where this service earns its place is in the multi-door properties: the apartments concentrated near the Sepulveda Boulevard corridor, the newer townhome development near Rinaldi Street, and the businesses spread along Devonshire Street and around the Mission district near San Fernando Mission.
Take an apartment building in the 91345 ZIP code along Sepulveda Boulevard. The usual pattern is a lot of individual unit locks, plus shared doors like a laundry room, a trash enclosure, a pool or courtyard gate, and a utility closet. A manager who is called to a lockout on that corridor needs one key that gets into the unit, not a ring of mismatched ones. That is a proper apartment master key system: each tenant's key opens only their unit and the shared doors they use, the manager's key opens the units, and the owner's grand master sits above both. If you manage rentals, our locksmith for landlords page covers the wider picture of turnover and unit rekeys.
Commercial and professional offices near Providence Holy Cross Medical Center and along Devonshire Street have a different need. Suites, supply rooms, and records rooms need layered access, and staff change. For those, an employee key control system with restricted keyways keeps a departing employee's key from becoming a permanent problem. Many of these doors also carry panic hardware and closers, and the lock cylinder in that hardware has to be pinned to the same chart. We coordinate that with commercial door hardware work so the system does not stop at the exit device.
One local detail worth knowing: Mission Hills sits in the north valley, with hotter summers than the basin and periodic Santa Ana wind exposure near the 118 corridor, which dries out door seals and weatherstripping. A door that drags, sticks, or does not latch cleanly puts extra load on its lock, and it often gets blamed on the new key system when the door itself is the cause. We check door fit during the walk-through so the system starts on doors that close properly.
We serve Mission Hills from our Westwood storefront at 10740 Wilshire Blvd and from mobile service vans, about 17 miles from base. The rest of what we do in this area is on our Mission Hills locksmith page.
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Call (213) 577-1366What a master key system will not do: security trade-offs we tell you up front
A master key system is a trade between convenience and absolute security, and you should hear that from the person installing it. Because each master-keyed lock has extra pin positions, there are more combinations that can open it. That makes a master-keyed lock somewhat easier to pick or manipulate than a single-key lock of the same quality. For most offices and apartments the trade is well worth it, but for a door guarding something truly sensitive, a separate lock outside the system may be the better choice.
We will also tell you where a system is not the right answer. If you have one front door, a back door, and three employees, a straightforward rekey so everyone carries one key is usually enough, and you can read about that on our lock rekey page. If you want to track who entered and when, rather than who holds a key, an electronic option may suit you better, and that is covered under access control installation.
A restricted keyway protects against casual copying, not against a determined attacker. It is one layer. Its job is to keep your keys from being duplicated without your say-so, and it does that job well when the authorization process is actually followed.
Why call Wilshire Lock & Key for a master key system
Wilshire Lock & Key has been in business since 1987, and we serve 140 cities across Los Angeles and Ventura counties. That matters on a job like this because a key system is something you live with for years, and you want the company that designed it to still be around when you add a door or replace a lost key in year eight.
We are one company with a storefront and our own mobile vans. We do not pass your call to a dispatch middleman who sends whoever is free. The person who plans your system is the same company that cuts the keys and does the install, with David as owner and lead technician overseeing the work. Our phone line, (213) 577-1366, is answered 24 hours a day, 7 days a week, year-round, so a key emergency or a lost master does not have to wait until Monday.
One more point on trust. California requires locksmith companies to hold a BSIS LCO license, and you should ask any locksmith for their license number before they start work, particularly on something as sensitive as a master key system, where the company will hold a record of how your building opens. That is a reasonable question and a good company will not mind it.
Frequently asked questions
What is the difference between a master key system and just rekeying all my locks to match?
Rekeying to match gives every lock the same key, so everyone who holds one can open everything. A master key system gives each person their own key for their own doors, with higher-level keys opening wider groups. If everyone should have identical access, a plain rekey is simpler. If access should differ by person or role, a master key system is the right tool.
Can you convert my existing locks to a master key system?
Often yes. If the existing cylinders are in good condition and are a type that can accept extra pinning, they can be re-pinned to a master chart, which is usually the more economical route. Worn, mismatched, or very old cylinders may need replacing. We check during the walk-through and tell you which doors can be converted and which cannot.
How does a restricted keyway stop people copying my keys?
The key blanks for a restricted keyway are controlled by the manufacturer and are not sold over the counter. Copies are made only through authorized channels with the right paperwork. That keeps a key from being duplicated at a kiosk or hardware store without your approval. It is a strong deterrent to casual copying, not a defense against every kind of attack.
Is a duplicate-protected key the same as a key stamped Do Not Duplicate?
No. A stamp is only a request, and an open-keyway key can still be copied by anyone willing to ignore it. A genuinely duplicate-protected key is cut on a restricted blank, so the protection comes from the blank and the authorization process behind it, not from the words on the key.
Do apartment buildings in Mission Hills need a master key system?
Many do, particularly buildings with multiple units plus shared doors like laundry rooms, trash enclosures, and gates. It lets a manager open units without carrying a ring of mismatched keys and keeps tenants' keys limited to their own doors. Smaller properties may be fine with a simple rekey instead. We will tell you which fits after seeing the building.
What happens if someone loses a master key?
It depends on the level. A lost change key is a small problem, since it only opens one door. A lost master or grand master is serious because it opens many doors. The fix may involve rekeying the affected group, and removable-core systems make that faster. This is why we recommend keeping the top-level keys with very few people and logging them.
Can new keys be added to the system later?
Yes, and a system is designed for that. The keying chart records the structure so new change keys can be cut without disturbing the rest. On a restricted system, new keys require authorization from the person named on your account. That is part of what makes the system controllable over time.
Will a master key system work with my panic bars and door closers?
The lock cylinders inside exit devices can be keyed into the same system, and we do that so the chart covers the whole door. The panic hardware and closers themselves are separate hardware that must be in working order. If they need repair or replacement, we can handle that alongside the system, including through our door closer repair service.
Can I call at night or on a weekend about a key control problem?
Yes. Our line at (213) 577-1366 is answered 24 hours a day, 7 days a week, year-round. For an urgent problem, such as a lost master key, tell us that on the call. Full system design is better done in a planned visit, but we can help you secure the building in the meantime.
Where do I start if I think I need a master key system?
Call us and tell us roughly how many doors you have, how many people need keys, and what has gone wrong with your current setup. From there we arrange a walk-through of the property, plan the hierarchy with you, and explain the options, including whether a simpler rekey would do the job.
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Reviewed by David, Owner & Lead Technician, Wilshire Lock & Key — in the locksmith trade since 1987.
Last updated 2026-10-11.