What is Rekeying?

Rekeying means changing the internal configuration of a lock so old keys no longer work. You keep the same lock body but swap or change the pins inside the cylinder. A locksmith can do this on-site for most residential and many commercial locks.

• When it’s useful: after tenant turnover, lost keys, employee changes, or when you want to limit access without replacing hardware.
• What it costs: usually significantly less than full lock replacement because you keep the lock and only change the internal parts.
• Time: most single-lock rekeys take under 30 minutes for a professional.

What is a Master Key System?

A master key system lets multiple keys operate a set of locks, while also allowing specific keys to open only certain locks. For example, a tenant key opens one apartment door. A manager key opens every apartment in the building. This works by adding additional pin combinations inside the cylinder so different keys align different sets of pins.

Grand Master Key Systems

A grand master key sits above several master groups. Think of a small complex with three buildings. Each building has its own master key. The grand master key opens every door in all three buildings. This adds convenience but also concentrates risk. Keep the number of grand master keys low and strictly controlled.

Key Control and Documentation

A master key system is only as safe as the way you manage keys. Keep an accurate log of who has which key. Limit the number of master and grand master keys. When keys are issued, require signatures and set return policies for staff and contractors.

• Use key tracking with dates and holder names
• Consider serialized keys or restricted keyways that require authorization for duplication
• Schedule periodic audits of key holders and access needs

Security trade offs

Master key systems increase convenience but also increase the impact if a key is lost or stolen. The larger the group a key opens, the larger the exposure. For high-risk areas use additional protections such as electronic readers, door alarms, or secondary locks.

Consider electronic access

If tracking, revoking, and scaling access are priorities, electronic access control can simplify key management. Cards, fobs, and mobile credentials allow fast revocation and create an audit trail. They work well with or instead of traditional master key systems.

Rekeying a Single Lock

1. Lock is removed or the cylinder is accessed at the door.
2. Locksmith disassembles the cylinder and replaces the pin tumblers to match a new key.
3. New key is cut and tested. Old keys will no longer operate the lock.
4. Cylinder is reinstalled and operation is confirmed.

Setting up a Master Key System

1. Survey all locks and determine groups and access levels.
2. Design the keying schedule and record the master key hierarchy.
3. Select compatible cylinders or provide rekeying where possible.
4. Install or modify cylinders with appropriate pinning to create the hierarchy.
5. Issue keys with strict tracking and document the system.

Will rekeying stop someone with an old key?

Yes. Rekeying replaces the internal pinning so old keys no longer work. That is the main reason property owners rekey after tenant changes or lost keys.

Can I add master keying later?

Often yes. Many cylinders can be re-pinned to create master keying, but you must plan carefully. Adding master pins can slightly reduce mechanical reliability and increase the number of possible key combinations, so use a locksmith to design the system.

Is a grand master key a single point of failure?

It can be. The more doors one key opens, the greater the risk if it is lost. Use strict controls, limited distribution, and consider alternatives like electronic access where practical.