A tenant moves out of a multi-tenant office building or retail strip. They turn in their keys — or they say they do. Maybe there were extra copies. Maybe a former employee of theirs kept one. Maybe a contractor who did buildout work years ago still has one sitting in a drawer.
Six months later, nobody at the property can answer a simple question: who currently has a working key to that unit? That’s the exact situation a rekeying protocol is built to prevent.
The Problem: Turnover Outpaces Tracking
Multi-tenant buildings turn over constantly. Tenants leave, subtenants come and go, staff changes, and every one of those events is a moment where a key could end up in the wrong hands. Most buildings don’t rekey on a fixed schedule tied to these events — they rekey reactively, if at all, usually only after something has already gone wrong.
The risk compounds because keys don’t expire on their own. A standard key cut five years ago for a tenant who left in year two still opens that door today, unless someone physically changed the lock. Without a rekeying protocol tied to specific triggers, a property has no reliable way to say how many working keys exist for any given unit.
This is especially common in strip retail and small office buildings, where units change hands more often than large anchor tenancies. A retail space might turn over every two or three years. Each time, there’s an assumption that the outgoing tenant handed back every key, but nobody actually confirms it. Contractors who did buildout or renovation work for that tenant may have been given a key temporarily and never asked to return it. Delivery services, cleaning crews, and alarm technicians sometimes end up with keys too, especially in buildings where access has historically been handled informally.
None of this is unusual. It’s just what happens by default when there’s no protocol forcing a different outcome.
When to Rekey
A structured protocol rekeys on defined triggers, not on a “when we get around to it” basis:
- Every tenant departure — rekey the unit before the next tenant moves in, full stop, regardless of how many keys were “returned”
- Lost or unaccounted-for keys — if a key can’t be physically confirmed as returned or destroyed, rekey
- Security incidents — any break-in, unauthorized entry, or suspicious access gets the affected locks rekeyed immediately
- Staff changes — when a property manager, maintenance employee, or anyone with master key access leaves
Treating tenant departure as an automatic rekey trigger — not a judgment call — is the single biggest change that closes the gap in most buildings.
Master Key System Implications
Most multi-tenant commercial buildings run a master key system: each tenant’s unit has its own key, and a master key (sometimes a sub-master for a floor or wing, plus a grand master for building staff) opens multiple units for maintenance and emergency access.
This structure means a single lost or uncontrolled master key is a much bigger problem than a lost individual tenant key. If a grand master is unaccounted for, every unit under that master is technically exposed, and the only real fix is rekeying the entire master system — not just one lock.
Because of this, master keys should be limited to as few people as possible, and a lost master should trigger an immediate, building-wide rekey conversation — not a “let’s keep an eye on it” response. When rekeying a multi-tenant building after a tenant departure, the individual unit gets a new key that still works under the existing master, so building staff retain access without having to touch every other unit.
Restricted Keyways as Prevention
The most effective long-term fix isn’t rekeying more often — it’s making unauthorized duplication impossible in the first place. Standard keyways can be copied at any hardware store. Restricted keyway systems from Medeco and Mul-T-Lock require a registered signature on file before a duplicate can be cut, and keys are stamped to indicate duplication is restricted. Pro Locksmith LLC is an authorized Mul-T-Lock dealer.
Putting a multi-tenant building on a restricted keyway doesn’t eliminate the need to rekey on turnover, but it drastically reduces the odds that a tenant walked away with an unauthorized copy nobody knows about. It turns “we hope they only had the keys we know about” into “we control who can make more.”
The Rekeying Process
Rekeying a commercial lock doesn’t require replacing the hardware. It means changing the internal pin combination so old keys stop working and new ones take over. For a multi-tenant building, the process looks like this:
- Pin new combinations into the affected locks, coordinated with the building’s master key system so building staff access isn’t disrupted
- Cut new keys for the incoming tenant or authorized staff
- Collect and destroy old keys wherever possible — this is also the point to update restricted keyway signature authorizations if applicable
- Update the key log to reflect the new combination, who received new keys, and the date
Skipping step 4 is common and it’s a mistake. A rekey that isn’t logged just resets the clock on the same tracking problem — the building still won’t know who has keys a few years from now.
Cost vs. Risk
Rekeying a lock costs a fraction of what a single unauthorized-entry incident costs a property in liability exposure, lost tenant trust, or insurance complications. Property managers sometimes push back on rekeying every unit at every turnover because it feels like an unnecessary recurring cost. It isn’t. It’s cheaper than the alternative: an incident where the building can’t demonstrate it controlled access to the unit in question.
The math is straightforward. Rekeying one commercial door lock is a single, predictable line item. An unauthorized-entry incident is not predictable, and the costs run well beyond the immediate loss — legal fees if the incident leads to a claim against the property, higher insurance premiums going forward, and the harder-to-quantify cost of a tenant who no longer trusts the building’s security and either leaves or tells other prospective tenants about it. Treating rekeying as a routine turnover expense, built into the cost of re-leasing a unit, keeps it in proportion. Treating it as an optional expense to skip when things are busy is how buildings end up exposed.
COI and Key Access Documentation
Any locksmith, contractor, or vendor performing rekeying work — or receiving keys as part of their work — on a commercial property should provide a certificate of insurance before that access happens. This isn’t paperwork for its own sake. If something goes wrong during or after the work, the COI is what protects the property.
Pro Locksmith LLC provides a certificate of insurance on request for every commercial job. We’re licensed and insured, our technicians are employees rather than subcontractors, and we quote flat-rate pricing before we start — no surprise charges after the fact.
Coordinating Rekeying with Lease Turnover
The most efficient time to rekey is during the gap between one tenant’s move-out and the next tenant’s move-in — when the unit is empty and there’s no conflict over access. Building this into the standard turnover checklist, alongside things like cleaning and inspection walk-throughs, means rekeying happens automatically rather than depending on someone remembering to schedule it separately.
Properties that manage several units across a building benefit from batching this work when possible — scheduling a locksmith visit that covers multiple vacant units in one trip rather than calling separately for each one. This is worth planning for at lease renewal time too: knowing which units are turning over in a given month lets a property manager schedule rekeying efficiently instead of reacting unit by unit.
Putting It Together
A workable rekeying protocol for a multi-tenant building has three parts: clear triggers for when to rekey, a restricted keyway to prevent unauthorized duplication between rekeys, and a key log that’s actually kept up to date. None of the three works well without the other two. A restricted keyway doesn’t help if you never rekey on turnover. A rekey schedule doesn’t help if the same standard keys can be duplicated at any hardware store the next day.
The building that gets this right isn’t necessarily spending more on security — it’s spending the same money on the right things, at the right time, consistently. That consistency is what actually closes the gap between “we think we know who has keys” and “we know who has keys.”
Pro Locksmith LLC handles commercial rekeying for multi-tenant buildings across Hollywood, Fort Lauderdale, Pembroke Pines, Davie, Pompano Beach, and Coral Springs. We set up restricted key systems, rekey on tenant turnover, and maintain the master key structure so building staff access isn’t disrupted during the process.
Sources: Medeco and Mul-T-Lock restricted key system product literature. Pro Locksmith LLC is an authorized Mul-T-Lock dealer.