Change or Rekey All Exterior Door Locks — Michigan
Complete checklist with climate-adjusted recommendations for Michigan
Overview
You don't know who has copies of existing keys. Rekey or replace all exterior door locks as soon as you take ownership of a new home.
Step-by-Step Guide
Inventory every exterior lock
Walk the entire perimeter of the home and list every exterior door — front, back, side, garage entry, and basement walkout. Note the lock brand and type (deadbolt, knob lock, smart lock) on each door.
Decide between rekeying and replacing
Rekeying changes the internal pins so old keys no longer work and is cheaper ($15–$25 per lock if DIY, $50–$100 per lock for a locksmith). Full replacement is better if locks are worn, outdated, or you want to upgrade to smart locks or higher-security deadbolts.
Purchase a rekey kit or new locks
For rekeying, buy a brand-specific rekey kit (Kwikset SmartKey or Schlage rekey kit). For replacement, choose ANSI Grade 1 or Grade 2 deadbolts. Consider keyed-alike sets so one key works on every door.
Remove the lock cylinder
For rekeying: insert the current key, turn to the unlock position, then insert the rekey tool to release the cylinder plug. For replacement: unscrew the interior mounting plate and pull both halves of the lock apart from the door.
Rekey the cylinder or install the new hardware
Follow the rekey kit instructions to swap the pin tumblers to match the new key. For new hardware, insert the latch assembly, align the exterior and interior assemblies, and tighten the mounting screws without overtightening.
Test every lock thoroughly
Test each lock with the new key from both inside and outside. Verify the deadbolt extends fully, the latch engages the strike plate cleanly, and the door can be locked and unlocked without forcing. Test the old key to confirm it no longer works.
Secure spare keys and update access
Make two spare copies of the new key. Store one in a secure location outside the home (trusted neighbor, lockbox). Update any keypad codes or smart lock access if applicable. Discard or repurpose old keys.
What You'll Need
Tools
- - Screwdriver (Phillips and flathead)
- - Rekey kit (brand-specific)
- - Needle-nose pliers
- - Measuring tape
Materials
- - New lock cylinders or complete locksets
- - Rekey pins (included in rekey kit)
- - Replacement strike plates (if needed)
- - 3-inch screws for deadbolt strike plates
Cost Estimates
DIY Cost
$15–$50 per lock (rekey kit) or $30–$100 per lock (full replacement)
Professional Cost
$50–$150 per lock (locksmith rekeying or installation)
Safety Tips
- Never leave exterior doors unlocked while working — rekey one door at a time.
- Keep at least one functioning lock on a door you can access at all times during the process.
- If a lock mechanism feels damaged or the bolt is misaligned, replace the entire unit rather than rekeying.
When to Call a Professional
Call a locksmith if you have high-security locks (Medeco, Mul-T-Lock), if you want a master-key system for multiple locks, or if the door frame or strike plate is damaged and needs reinforcement.
Pro Tip
When buying new deadbolts, choose ones with a reinforced strike plate and 3-inch screws that anchor into the door frame studs — not just the trim. This dramatically increases kick-in resistance.
Common Mistakes to Avoid
- Forgetting the garage entry door or basement walkout door.
- Mixing up rekey pins and jamming the cylinder — always follow the exact pin order in the kit.
- Overtightening mounting screws, which warps the lock housing and makes the key hard to turn.
- Not testing the old key after rekeying to confirm it truly no longer works.
- Skipping the sliding glass door — add a security bar or replace the latch if it can be jimmied.
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