A master key system lets one key open every door in a building while each tenant’s key opens only their own. In the Tacoma area it is priced per door to set up, with unit rekeys at turnover priced per cylinder, and most apartment buildings need only 3 key levels.
For a property manager, the payoff is one key ring instead of forty, controlled duplication, and a documented record of who can open what. Peak Locksmith designs, installs, and maintains these systems for apartments, offices, and mixed-use buildings across Pierce County.
This guide explains how the mechanism works, how to design a hierarchy that will not collapse in three years, what key control really means, what Washington law expects of landlords, and when a building has outgrown mechanical keys.
How a Master Key System Works Mechanically
A standard pin tumbler cylinder has one shear line: the key lifts each pin stack so the split between bottom pin and top pin sits at the gap between plug and housing. A master-keyed cylinder adds a thin master wafer to some or all stacks. That creates a second split in each stack, so two different key cuts will both align a valid shear line. The change key (the tenant’s key) uses one set of positions, the master key uses the other.
The cost of that flexibility is a small loss of pick resistance and a finite number of usable key combinations. A well-designed system reserves combinations, avoids cuts that let a change key accidentally operate a neighbor’s door (cross-keying), and leaves room for expansion. A badly designed one, usually one that grew door by door over a decade, ends up with “ghost keys” that open doors nobody intended.
The Hierarchy: Grand Master, Master, Change Key
| Level | Opens | Who typically holds it |
|---|---|---|
| Great grand master (GGMK) | Every door across multiple buildings | Owner or regional manager |
| Grand master (GMK) | Every door in one building | Property manager |
| Master (MK) | One floor, wing, or department | Maintenance lead, floor supervisor |
| Sub-master or maintenance key | Utility rooms, mechanical spaces | Maintenance staff, vendors |
| Change key (CK) | One unit or office | Tenant or employee |
Most Tacoma apartment buildings need only three levels: a grand master for the manager, a maintenance master for common areas and mechanical rooms, and change keys per unit. Adding levels you do not need eats combinations and weakens pick resistance without benefit.
Where These Systems Fit in Pierce County
- Older multifamily in Hilltop, Stadium District, and the North End (98403, 98405). Brick walk-ups from the 1910s to 1940s often carry a mix of mortise and cylindrical hardware added over decades. The first job is usually standardizing on one keyway before a system can be built.
- Garden-style complexes in Lakewood, Parkland, and South Tacoma (98444, 98445, 98499, 98409). High tenant turnover near Joint Base Lewis-McChord and Pacific Lutheran University makes fast, cheap unit rekeys the priority. Interchangeable core cylinders shine here.
- Downtown offices and medical suites (98402, 98405). Departmental masters, restricted keyways, and a written key log matter more than speed.
- Student housing near UW Tacoma and University of Puget Sound. Annual turnover means a full-building rekey cycle every summer; plan the system around that calendar.
Key Control: The Part Most Systems Skip
A master key system is only as strong as the rules around copying keys. Any Kwikset or Schlage change key can be duplicated at a hardware store for a few dollars, and so can the master if it leaves the office. Three tools close that gap:
- Restricted or patented keyways. Blanks for Schlage Everest, Medeco, Mul-T-Lock, and similar systems are sold only to the authorized locksmith of record, who cuts them only against a signed authorization from the property. Expect a higher per-cylinder and per-key price than standard hardware.
- A key log. Serial-numbered keys, a signature on issue and return, and a quarterly audit. A spreadsheet is enough. Without it, you cannot know when the system has been compromised.
- Bitting records held by the locksmith. The system’s pinning chart is what lets new doors be added without breaking the hierarchy. Keep a copy off site.
A 2003 research paper showed that anyone holding one change key and access to the lock can derive the master key by filing test keys. Restricted keyways stop that attack because the attacker cannot buy blanks, which is why patented keyways are the first upgrade we recommend for any building where the master would matter to a burglar.
Turnover: Rekeying Units Without Rebuilding the System
When a tenant leaves, the unit’s change key is retired and the cylinder is repinned to the next unused combination in the chart; the master keeps working. That is a small per-cylinder job done in minutes. Interchangeable core (IC) cylinders go further: the manager swaps the core with a control key in thirty seconds and hands the old core to the locksmith later. IC hardware costs more per door up front and pays back within a couple of turnovers in a high-churn building.
Our guide to rekey versus replace covers when a worn unit lock should be swapped rather than repinned.
What Washington Law Expects
The Residential Landlord-Tenant Act sets the baseline. RCW 59.18.060 requires the landlord to provide reasonably adequate locks and furnish keys. RCW 59.18.575 requires a landlord to change or rekey a tenant’s locks at the tenant’s request when the tenant provides a protection order or a report of domestic violence, sexual assault, or stalking, and to do so promptly; the tenant may be charged the cost. RCW 59.18.130 obliges tenants not to change locks without consent in most leases, and a master system depends on that rule being enforced. Nothing in state law requires rekeying between tenants, but the per-cylinder cost is small next to the liability of a prior tenant’s key still working.
What Drives the Cost in the Tacoma Area
| Item | What drives the price |
|---|---|
| System design and pinning chart | Number of doors and levels |
| Repin an existing standard cylinder into the system | Per door; the lowest-cost option |
| New commercial-grade cylinder, standard keyway | Per door installed |
| New restricted-keyway cylinder | Per door installed; patented blanks cost more |
| Interchangeable core upgrade | Additional per door |
| Keys, standard versus restricted | Restricted blanks cost more per key |
| Unit rekey at turnover | Per cylinder |
A 24-unit building in Lakewood with a lobby, laundry, and two mechanical rooms is quoted after a door count for a fresh three-level system, and a patented keyway roughly doubles the hardware cost. A full-building job takes one to two days.
When a Building Has Outgrown Keys
Once a property passes roughly fifty doors, has frequent vendor access, or needs an audit trail, electronic access control begins to cost less than the key problems it replaces. A lost master key on a mechanical system means rekeying every door it opened. A lost fob is deleted from the panel in a minute. Keypad, fob, and mobile-credential doors are priced per door depending on type. Our commercial security guide compares the options, and many Tacoma buildings run a hybrid: access control on exterior and common doors, mechanical master keying on unit doors.
Best Practices That Keep a System Working
- Standardize on one keyway per building before designing the hierarchy.
- Reserve at least 30 percent of combinations for future doors.
- Limit the grand master to two holders and store one in a safe.
- Log every key by serial number and audit quarterly.
- Rekey the grand master level whenever a master key is lost, not just the affected doors.
- Pair the system with Grade 1 deadbolts and reinforced strikes on exterior doors; the cylinder is not the weakest point.
- Keep the pinning chart and locksmith of record on file with the owner, not only the manager.
When to Call Peak Locksmith
Call (253) 262-5630 to have a commercial locksmith walk your building, count doors and hardware types, and quote a system design. We serve Tacoma, Lakewood, University Place, Puyallup, Federal Way, Fife, and all of Pierce County, handle same-day unit rekeys at turnover, and hold your pinning chart so new doors can be added without starting over. For a single lost key or a lockout at a unit, our emergency locksmith team is available around the clock.
Frequently Asked Questions
How much does a master key system cost for an apartment building in Tacoma?
It is priced per door to repin existing cylinders into a new system, plus a system design charge based on the number of doors and levels; new cylinders cost more per door, and a restricted keyway more again. A 24-unit building is quoted after a door count, and a patented keyway roughly doubles the hardware cost.
Does master keying make locks less secure?
Slightly. Each master wafer adds a second valid shear point in a pin stack, which gives a picker more chances and reduces the total number of safe key combinations. A properly designed system with security pins and a restricted keyway offsets this, and in practice the far larger risk is uncontrolled key copying, which restricted blanks prevent.
What happens if a master key is lost?
Every cylinder that master opened must be repinned to a new master combination, which is why the master level should have as few holders as possible. In a 24-unit building that is typically a one-day job, priced per door. Interchangeable core systems reduce the disruption because cores can be swapped by staff and repinned later.
Do Washington landlords have to rekey between tenants?
No state statute requires a rekey at every turnover. RCW 59.18.060 requires adequate locks and keys, and RCW 59.18.575 requires a lock change when a tenant with a protection order or a documented report of domestic violence requests one. Most Pierce County managers rekey at turnover anyway because a cylinder rekey is inexpensive and removes the liability.
Can a master key system be expanded later?
Yes, if the original pinning chart reserved combinations and the locksmith of record still holds it. New doors are pinned to unused combinations under the existing master. Systems that were built ad hoc, or whose records were lost, often cannot be extended safely and are rebuilt instead, which is why we recommend keeping the chart with the owner.
When should a building switch from master keys to access control?
Consider electronic access control once a property has roughly fifty or more doors, frequent vendor and contractor access, or a need for entry logs. A lost fob is deleted in a minute, while a lost master key means repinning every door it opened. Many Tacoma buildings run a hybrid, with fobs on exterior and common doors and mechanical master keying on units.
