A master key system gives every door its own key while one master opens all of them. The owner carries the master; each tenant, room or office gets a change key that opens only their door. We design, pin and document systems for small apartment buildings, HOAs, churches, offices and duplexes across San Diego County, on conventional pin-tumbler cylinders, with the master on a restricted keyway if you want it.
What you get
- One master for the owner, one change key per unit, room or office
- Designed on paper first: levels, key schedule, spare keys for future doors
- Built on your existing Kwikset or Schlage cylinders where they qualify
- Master level on a restricted keyway so it cannot be copied at a kiosk
- Written key schedule and key count for your records
What a master key system is
A master key system gives every door its own key while one higher-level key opens all of them. The owner or manager carries the master. Each tenant, room or office gets a change key that opens only their door.
It works by adding master pins to each pin-tumbler cylinder so two different keys reach the shear line: the change key cut for that door and the master cut for the whole system. Nothing about the door hardware changes. The cylinders are re-pinned and put back.
That is different from keyed alike, where every lock takes the same key and everyone opens everything. A master key system is for buildings where different people should open different doors. It is set up once, then maintained as doors and people change.
Where a master key system fits
You do not need a large building. The systems we design most often are small:
- Apartment buildings of four to thirty units, where each tenant has a change key and the manager has one master for units, laundry and storage. Common in the older multi-family blocks of North Park and Pacific Beach.
- HOAs with a pool gate, clubhouse, fitness room and utility closets that the board, the management company and vendors need in different combinations.
- Churches where volunteers hold keys to the kitchen or nursery and the pastor and facilities lead hold the master.
- Schools, preschools, offices and medical suites, such as the practices around Kearny Mesa, with exam rooms, records rooms and staff entries.
- Duplexes and ADUs: the owner's master opens both units, each tenant's key opens one.
See how this plays out for property managers and HOA boards.
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Designing the system: levels, change keys and the key schedule
Every system starts on paper. We list the doors, ask who needs to open what, and build levels from there.
- Change keys open one door or one unit.
- Sub-masters open a group: one building in a complex, one floor, or the maintenance doors only.
- The master opens everything in the system.
Two levels cover most small buildings. Three make sense when a management company, an on-site manager and a cleaning crew each need a different reach. We keep levels to the minimum, because every extra level adds master pins to every cylinder and shrinks the number of usable key combinations.
The result is a key schedule: a written list of every door, the key that opens it, and how many keys were issued. We also hold spare change keys in reserve so a new unit, a converted garage or a new office can be added later without re-pinning the building.
Hardware reality: which locks can be master keyed
Master keying needs conventional pin-tumbler cylinders that all share one keyway. Two questions decide whether your existing locks qualify.
Is it SmartKey? Kwikset SmartKey cylinders, the ones with a small rekey hole beside the keyway, cannot be master keyed. The mechanism has no room for master pins. A building full of SmartKey deadbolts needs its exterior cylinders swapped to conventional Kwikset or Schlage cylinders before a master can be built.
Same keyway everywhere? Conventional Kwikset KW1 and Schlage SC1 cylinders both master key, but not with each other, so we standardize on one. Six-pin commercial Schlage cylinders give a system more room to grow than five-pin residential ones, which matters if the building will add doors.
For buildings with frequent changes, small format and large format interchangeable cores let a manager swap a whole core with a control key instead of calling us. How cores fit a business is on the commercial rekey page.
Key control: keep the master on a restricted keyway
A master key system only stays a system while you know how many masters exist. On a standard Kwikset or Schlage keyway anyone holding a master can copy it at a hardware store, and a Do Not Duplicate stamp does not stop them.
The fix most small buildings choose is a split. Tenant change keys stay on standard cylinders, and the master level runs on a restricted keyway where blanks are controlled and new keys are cut only for names on your authorization list. Schlage Primus is built for exactly this: a Primus master carries side milling a standard key cannot copy, yet it still turns the conventional Schlage cylinders on tenant doors.
A lost change key then costs one cylinder rekey. A lost master still means re-pinning every door, which is why the master deserves the protection. Options are on our high-security and restricted keys page. Decide before the system is pinned; changing keyways later means new cylinders.
Keyed alike or master keyed?
People often ask for a master key when what they want is keyed alike, and the reverse. This is how we decide.
| Keyed alike | Master keyed | |
|---|---|---|
| Who opens what | Everyone opens every door | Each key opens its own door; the master opens all |
| Best for | One household, an ADU the owner also uses, a small shop | Rentals, HOAs, churches, schools, offices |
| Hardware | Any cylinders on a matching keyway, SmartKey included | Conventional pin-tumbler cylinders, no SmartKey |
| Cost | A normal rekey | Design plus pinning, quoted per door |
| Lost key | Rekey every door | Change key: one door. Master: every door |
| Adding a door later | Rekey it to the key | Pin it from the key schedule |
Keyed alike has its own page. A landlord with one house and a granny flat usually wants the smallest possible system: a tenant key per unit and an owner master, handled like a landlord turnover with one extra step.
What the visit looks like and how we document it
- Door survey. We list every door and cylinder, note the keyway and any SmartKey hardware, and confirm who should open what.
- Design. We chart the levels and the key schedule before pinning anything and send it for your sign-off.
- Pinning. Each cylinder is pulled, re-pinned to its change key and the master, tested with both keys and reinstalled. Doors are out of service for minutes each.
- Keys. Change keys are cut and tagged by unit. Masters are cut only in the number you approve.
- Records. You get the key schedule, the key count and, for restricted systems, the authorization list we hold.
Keep the schedule with your building records. When a unit turns over we re-pin that cylinder to a fresh change key and update the schedule; the master keeps working. Landlords can read the turnover side in rekeying between tenants in California, and boards the common-area side in HOA and condo lock rules.
Master Key Systems: common questions
Can a master key system be added to my existing locks?
Often, yes. If the locks are conventional pin-tumbler cylinders on one keyway, all Kwikset KW1 or all Schlage SC1, we re-pin them in place and the hardware stays. Kwikset SmartKey cylinders cannot be master keyed and get swapped for conventional cylinders in the same housings. Mixed keyways mean standardizing on one, usually by swapping the minority.
Is a master key system the same as keyed alike?
No. Keyed alike means one key opens every lock, so everyone with that key opens everything. Master keyed means each door has its own key and a separate master opens all of them. Keyed alike suits one household. Master keying suits rentals, churches, HOAs and offices where different people need different access.
What happens when a tenant loses a change key?
We re-pin that unit's cylinder to a new change key and cut fresh keys for the tenant. The master keeps working because the master pins stay in place. It is a single-door rekey, not a system change, and we update the key schedule so the record stays accurate.
What happens if the master key is lost?
Every cylinder in the system has to be re-pinned to a new master, because the old master opens all of them. That is the main risk of any master system and why we recommend the master level on a restricted keyway with a small, recorded number of copies. Change keys usually stay the same during that re-pin.
How many levels should my building have?
As few as possible. Two levels, change keys and one master, cover most small apartment buildings, churches and offices. Add a sub-master only when a group of people genuinely needs a group of doors, such as maintenance staff or one building in a complex. Every extra level adds master pins and reduces the combinations left for future doors.
Can a master key system include the pool gate and the mailboxes in an HOA?
Gates and common-area doors with standard cylinders can join the system. Mailbox compartment locks cannot: they are small cam locks on their own keys, and USPS controls the carrier arrow lock. We put the pool gate, clubhouse and utility doors on the master and handle mailbox locks separately in the same visit.
More answers on the FAQ page. Not sure what your door has? Send us a photo and we will tell you.
Where we do this
We do this everywhere in San Diego County, same day in most cases. Some of the places we cover:
Related guides
- Rekeying Between Tenants in California: What Landlords Should Know – California has no statewide law forcing landlords to rekey between tenants, but deadbolt rules, liability and cost point the same way. A San Diego guide.
- HOA and Condo Lock Rules in San Diego: What You Can Change – Which locks a San Diego condo owner controls, what the HOA can restrict, how to get a smart lock approved, and what fire-rated doors mean for your options.
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