Rekeying vs. Replacing Locks: Costs, Security, and When to Choose Each

1. The Fundamental Difference: Mechanism vs. Hardware

When securing a residential home, rental apartment, or commercial facility, property owners frequently assume that changing keys requires buying brand-new locksets from a hardware store. In reality, modern pin-tumbler locks separate the key recognition cylinder from the physical deadbolt body.

A lock cylinder contains a brass plug housed inside an outer shell. Inside are pairs of spring-loaded pins: driver pins on top and key pins on the bottom. When you insert a key, the cuts in the key raise the key pins so the dividing line between pins aligns perfectly with the cylinder’s shear line. Turning the key throws or retracts the deadbolt.

When you rekey: A technician disassembles the cylinder, removes the existing bottom key pins, and drops in new pins calibrated to a brand-new key bitting code. The physical lock body, deadbolt latch, strike plate, and exterior brass trim remain untouched.

When you replace: The entire assembly is removed from the door slab and door jamb, and new hardware is drilled or fitted into place.

2. Side-by-Side Comparison: Rekeying vs. Replacing

The following comparison table highlights key cost, timeline, and operational differences:

3. When Rekeying Is the Smarter Choice

Rekeying is the preferred recommendation in the majority of routine residential access transitions:

• Moving Into a Newly Purchased Home: Previous owners, real estate agents, home inspectors, cleaning crews, and contractors may all possess duplicate keys. Rekeying resets access immediately at a fraction of the cost of new hardware.
• Tenant Turnover in Rental Properties: For Pennsylvania landlords and property managers, rekeying between tenancies ensures former tenants cannot access the unit while avoiding repeated hardware purchases.
• Lost or Stolen Keys: If a family member loses a house key and you are unsure if it was labeled or traced to your address, rekeying renders the lost key harmless.
• Consolidating to One Master Key: If your front door, back door, garage entry, and deadbolts all use different keys, a locksmith can rekey all compatible cylinders to operate from one single key.

4. When Replacing the Lock Is Mandatory

While rekeying solves key control, it cannot repair compromised or substandard metal hardware:

• Mechanical Wear & Slop: If a key wiggles excessively, the deadbolt binds, or internal springs have collapsed, rekeying will not fix the mechanical failure. Replacement is required.
• Contractor-Grade (ANSI Grade 3) Hardware: Many subdivision homes are fitted with cheap builder-grade locks with stamped steel deadbolts. Upgrading to an ANSI Grade 1 or Grade 2 solid brass cylinder drastically improves kick-in resistance.
• Upgrading to Smart Keyless Entry: If you want keypad access, smartphone app control, or temporary guest codes, the mechanical lock must be replaced with a smart electronic deadbolt.
• Style & Finish Remodeling: When changing door colors, modernizing exterior handlesets, or replacing polished brass with matte black or satin nickel.

5. The Keyed-Alike Advantage

A major benefit of professional locksmith service is keying alike. As long as your exterior locks share the same keyway brand family (e.g., all Schlage C-keyway, or all Kwikset KW1 keyway), a locksmith can adjust pin heights so that a single key unlocks your front deadbolt, front entry knob, side door, and back patio door.

If your home currently has a mix of brands (such as a Kwikset handle and a Schlage deadbolt), a technician can replace just the mismatched cylinder so all locks unify under one key.

6. Frequently Asked Questions