What is a master key system, and does a Westmont building need one?
A master key system is a plan for who can open what. Instead of one unrelated key per lock, the locks are built so each door has its own key, and a higher-level key opens a defined group of doors, or all of them. The owner of a small apartment building carries one key that opens every unit and the laundry room, while each tenant carries one key that opens only their own door and the shared entry. A shop owner holds a key for everything, while a part-time employee holds one that opens the front door and the stockroom and nothing else.
You probably need a commercial or business master key system if you carry more than a handful of keys for the same property, if you've lost track of who holds what, or if staff and tenant turnover has you changing locks more often than you'd like. You probably do not need one for a single-family house or a one-door shop. A plain lock rekey does that job, and it is usually the more economical route. We'll tell you that on the phone. A master key system adds complexity, and complexity only pays off when you have enough doors or people to justify it.
This page covers the planning side: key hierarchies, restricted keyways, duplicate-protected keys, and key control. Lockouts, repairs and single-door work are separate services, and we link to them where they come up.
How does a master key hierarchy work?
Most door cylinders are pin tumbler locks. A normal key lifts a stack of pins until the gaps line up at the shear line, and the cylinder turns. In a master-keyed cylinder, extra thin pins in some of the chambers create a second valid shear line. Two differently cut keys can then turn the same lock: the key for that door and the key for the group above it.
Systems are organized in levels. Most small properties only need two or three of them:
- Change key (sometimes called a day key): opens one lock only, such as a single apartment or a single office.
- Master key: opens a defined group, such as every unit on one floor or every door in one department.
- Grand master key: opens several groups, which usually means the whole building.
- Great grand master key: sits above that for campuses or multi-building sites, and is rarely needed for small properties.
What is the security trade-off of a master keyed lock?
Every additional shear line makes a cylinder slightly more tolerant of keys that are cut close to the right pattern, and it gives a would-be key-maker more combinations to work with. A well-planned two- or three-level system is a sound choice for an apartment building or a small business. A sprawling system with many levels and hundreds of doors needs more care in the design, and sometimes a different approach altogether.
There is another risk, and it comes from poor planning rather than the lock itself: unintended cross-keying, where one tenant's key also opens a neighbor's door. That is why we chart the whole hierarchy on paper before a single cylinder is pinned or a key is cut.
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Call (213) 577-1366What are restricted keyways and duplicate-protected keys?
A restricted keyway is a key profile that is controlled by the manufacturer. The blanks are not sold over the counter at a hardware store or a kiosk, so a stray copy is harder to make. Duplicate-protected keys go a step further: they are stamped, and copies require authorization, usually a signature or an ID check against a list the owner sets. Together they make up a restricted key system, and they are the backbone of serious key control.
We want to be straight about the limits. A restricted keyway stops casual copying. It does not make a lock pick-proof, and the protection is only as good as the rules around it. If the authorization card goes missing or the list of approved people grows too long, the protection fades. How long legal protection lasts also varies by product line, so we explain what a specific line does and does not give you before you choose it. Our high-security locks page covers the hardware side, and our key duplication service explains how authorized copies are handled once a system is in place.
How do we install a master key system?
The process is the same whether the job is a six-unit building or a shop with a back office. The steps below are how we work, and the order matters, because the paperwork comes before the hardware.
- You call and describe the property: how many doors, which ones are shared, and who needs access to what.
- We look at the doors, in person where possible. We count cylinders and note the type of each one: deadbolts, mortise locks, rim locks, padlocks, gate and mailbox locks.
- We draw the hierarchy as a key chart. This is where we decide the levels, who holds which key, and which spaces sit outside the master, such as an owner's office, a server closet or a storage cage.
- We choose the keyway and the hardware. That means a standard or a restricted keyway, and whether existing cylinders can be re-pinned or need replacing.
- We pin the cylinders and cut the keys from the chart, working from our Westwood storefront or from the van on site.
- We install, then test every door with every key that should open it and every key that should not. That second test is the one people skip, and it is the one that catches cross-keying.
- You get the key chart and instructions for ordering additional keys. We advise stamping keys with a code rather than a door number, so a lost key doesn't tell a stranger which door it fits.
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Call (213) 577-1366Can my existing locks be converted to a master key system?
Often yes, and this is the master key rekey route. If the cylinders are in good condition and from the same keyway family, we can re-pin them to fit the new hierarchy and keep the hardware you already have. That is usually the lighter-cost path.
It gets harder when a building has a mix of brands and keyways, because cylinders from different families cannot be master keyed together. Worn or damaged cylinders are another reason to replace rather than re-pin. In those cases we price the system as a hardware change, and we'll explain which locks must go and which can stay.
One more honest point: a mechanical master key system does not record who opened which door or when. If you need a log, or the ability to cancel one person's access instantly, mechanical keys alone won't do it. We'll discuss whether access control installation fits your situation, either instead of keys or alongside them for the doors that matter most.
What affects the cost of a master key system?
We don't quote numbers on a web page, because the honest answer depends on the property. These are the factors that move the cost up or down:
- How many cylinders are in the system, and how many distinct keys the hierarchy needs.
- How many levels the hierarchy has. Each added level means more planning, more pinning and more testing.
- Standard keyway or restricted keyway with duplicate-protected keys. Restricted systems cost more because of the controlled blanks and the authorization process.
- The condition and type of existing hardware: re-pinning what you have versus replacing cylinders or whole locks.
- The mix of lock types. Deadbolts, mortise locks, padlocks, gate locks and mailbox locks don't all share parts.
- How many keys you need cut at the start.
- Whether the work happens at an ordinary time or after hours.
What does a master key system look like in Westmont?
Westmont is an unincorporated part of Los Angeles County, covering ZIP codes 90044 and 90047. It is densely built, with 1920s-1940s bungalows and Spanish-style cottages, small postwar homes, and two-story apartment buildings along Vermont, Normandie and Western avenues. A large share of households are renters, so keys change hands often. That is the situation a master key system is made for.
Take a small multifamily building on the Normandie Avenue corridor. The manager holds a master key that opens each unit, the laundry room and the side gate. Each tenant holds a key for their own door and the shared entry. When a tenant moves out, we re-pin only that unit's cylinder to a new key, with no need to touch the master or any other tenant's key. That is the practical gain for rental turnovers in small multifamily buildings. If you manage several buildings, our page on locksmith services for landlords covers the wider picture.
Security screen doors and window bars are widespread here, so many front doors carry two locks. Depending on the hardware, we can key the screen door and the main door to the same key, so a tenant is not juggling extras. Mailbox locks along Vermont and Western avenues are a separate lock type. Whether one can join the key plan depends on the box, so we check it first, and our mailbox lock replacement service covers the cases where it can't.
On the commercial side, storefronts along the Century Boulevard and Manchester Avenue corridors usually need something simpler: an owner key, a manager key, and a staff key that opens the front and little else. If the door hardware itself is worn, that may call for storefront lock repair before any system is built on top of it. The same logic applies around the Vermont and Manchester intersection and near the Jesse Owens Park area, where residential streets meet small commercial strips. We also work on properties close to the Vermont Knolls and Morningside Park edges.
Climate matters a little. Westmont sits on a flat inland coastal plain with regular morning marine layer, and corrosion is minor. But damp winter mornings can swell older wood doors and frames, and a door that binds makes a good key system feel broken. When someone says a new key is sticking, we check how the door fits before we blame the cylinder.
Our storefront is at 10740 Wilshire Blvd in Westwood, about 14 miles from Westmont, and our mobile vans bring the key-cutting and re-pinning work to you.
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Call (213) 577-1366How do you set up employee key control for a shop or office?
An employee key control system is mostly habit, supported by the right hardware. The rules we suggest are short:
- Give each person the lowest key level that lets them do their job.
- Keep a written log of who holds which key, and update it when people leave.
- Use a restricted keyway with duplicate-protected keys so staff can't copy a key at a kiosk.
- Keep the number of people allowed to authorize copies as small as possible, ideally one or two.
- Stamp keys with a code, not with a door number or the business name.
- When someone leaves, collect their key and, for higher-level keys, re-pin the affected locks rather than hoping the key was never copied.
Why call Wilshire Lock & Key for a master key system?
We've been in business since 1987, and we serve 140 cities across Los Angeles and Ventura counties. A system design is only as good as the person who draws it, and David, our owner and lead technician, oversees the plans. We are one company with a storefront and our own mobile vans, not a call center passing your job to whoever is free, so the person who plans your system is the one you can call about it later.
Our phone at (213) 577-1366 is answered 24 hours a day, 7 days a week, year-round. If a master key goes missing at night, you don't have to wait for the next business day to talk to someone.
One thing to check with any locksmith, including us: California requires locksmith companies to hold a BSIS LCO license, and you should ask for the number before work starts and compare it with the state's records. For broader work on a business property, see our commercial locksmith page, or call and describe the building.
Frequently asked questions
What is the difference between a master key system and a regular rekey?
A rekey changes the locks so a new key works and the old one doesn't, usually making a set of locks open with a single key. A master key system builds a hierarchy: each lock has its own key and one or more higher-level keys also open it. If you only have one door or one household, a rekey is usually enough.
Can you convert my apartment building to a master key system without replacing every lock?
Often, yes. If the cylinders are in good condition and from the same keyway family, they can be re-pinned to fit the hierarchy. Mixed brands, worn cylinders or damaged hardware may have to be replaced. We confirm which in person after looking at the doors.
Are restricted keys impossible to copy?
No. A restricted keyway makes casual copying much harder because the blanks are controlled, and duplicate-protected keys require authorization before copies are made. But the protection depends on how you manage the authorization list and how long the product line's legal protection lasts. It is a strong deterrent, not a guarantee against every copy.
Is a master keyed lock less secure than a single-key lock?
Slightly, in principle, because each added shear line makes the cylinder more tolerant of near-matching keys. A well-designed system with two or three levels is a sound choice for most small buildings and businesses. Larger systems need more careful design, and we'll tell you if yours is getting too big.
What happens if a master key is lost?
It depends on the level. A lost change key means re-pinning one lock. A lost master or grand master key is more serious, because it opens a whole group of doors, and those locks usually need re-pinning to a new hierarchy. Call us as soon as you know, because the phone is answered around the clock.
Can I add new units or doors to the system later?
Usually yes, if the plan was drawn with room to grow. That is why we chart the hierarchy up front and keep the key chart. Adding to a system on the same keyway family is typically more economical than starting over, though a heavily expanded system may need to be redesigned.
Do you set up master key systems for small businesses with only a few employees?
Yes. A shop with an owner, a manager and a couple of staff can benefit from a simple two-level system, especially if you want a back office or stockroom that only certain people can open. If a plain rekey would do the job, we'll say so.
How do employee key control and access control compare?
Mechanical keys are simple and have no ongoing system to maintain, but they don't log who opened a door, and canceling one person's access means re-pinning locks. Access control can log use and cancel credentials instantly, but it is a different kind of installation. Many properties use keys for most doors and access control for a few.
What should I have ready when I call about a master key system?
The number of doors and what kind of locks they are, which doors are shared, and who needs access to what. Photos of the existing hardware help. You don't need to have the hierarchy worked out: that's the part we do with you. Call (213) 577-1366 any hour.
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Reviewed by David, Owner & Lead Technician, Wilshire Lock & Key — in the locksmith trade since 1987.
Last updated 2026-10-11.