Smart locks on old doors
Your door is a hundred years old, it has a mortise lock in it, and every smart lock on the shelf is built for a round hole. We convert the door instead of replacing it.
What actually goes wrong
A mortise lockset lives in a deep rectangular pocket cut into the edge of the door, with a separate hole through the face for the knob. It is a nineteenth-century way of hanging a lock and it is still the best one, which is why the doors that have them tend to be the doors worth keeping.
Modern smart locks are not built for it. They are built for a 2⅓-inch round bore, because that is what has been standard since the 1950s. So people buy the lock, take the old one out to fit it, and then discover the problem.
That is the point at which most locksmiths quote a new door, or tell you it cannot be done. It can be done. The pocket gets covered and reinforced by a conversion plate assembly, the face is prepped to take the new hardware, and the smart lock mounts to the plate rather than to the door. The door itself is left intact.
The same door, finished
Keypad, thumbturn and a matching lever on a single plate, on the original door. The mortise pocket underneath is still there — it is simply no longer your problem.
What it costs
| Which version | Price |
|---|---|
| You supply the smart lock conversion plates, door prep and installation | $1,150 |
| We supply everything smart lock and thumb-latch decorative handleset included | $2,000 |
What the price includes:
- The mobile service charge — no separate trip fee on top
- The conversion plate assembly, supplied and fitted
- Door prep on both the edge and the face, including making good the old pocket
- Fitting, aligning and testing the smart lock, and setting it up with you
- 90 days on our labour
What costs extra, and how much:
- A smart lock, if you would rather we supplied it — $500
- A matching thumb-latch decorative handleset — $350
- A second door converted on the same visit — quoted on site, considerably less
- After 5 PM — see the after-hours rate
Prices shown are in effect from August 2026 and remain in effect until updated on this page. Final price is confirmed with you before any work begins. Older doors are not square and no two of these jobs are identical. Send a photo of the door edge and the face before you book and we will confirm the number before anyone drives out. Estimates by photo are free.
Common questions
Can you put a smart lock on a door with an old mortise lock?
Yes, and it is one of the jobs we do most often. An old mortise lockset sits in a deep rectangular pocket cut into the edge of the door. Modern smart locks are built for a round bore, so they will not simply drop in. The fix is a conversion plate assembly that covers and reinforces the old pocket, plus the door prep to take the new hardware. The original door stays. Nothing gets replaced that does not need replacing.
I already pulled the old lock out and now there is a big hole. Can it be saved?
Almost always, and you are not the first. Removing the lockset leaves a rectangular void in the edge of the door and a torn-out hole on the face, and at that point no standard lock will mount to it. That is exactly what the conversion plate is for. Send us a photo of the door edge and the face and we will tell you before we drive out.
Do I have to buy the lock from you?
No. If you have already bought a smart lock, we fit it — $1,150 all in for the conversion plates, the door prep and the installation, including the mobile service charge. If you would rather we supplied everything, the full job with a smart lock and a matching thumb-latch handleset is $2,000.
Will it damage the door?
No. The conversion plate is designed to cover the existing mortise pocket, which means the damage that is already there gets hidden rather than extended. On a hundred-year-old door that is the whole point — the alternative most people are quoted is a new door.
How long does it take?
Most conversions are a two to three hour visit, done in one trip. Older doors are rarely square and the prep is the slow part, which is why this is priced as a job rather than by the hour.
Does the guarantee cover it?
90 days on our labour, as with every job. If we supplied the smart lock as part of the package, the lock carries its manufacturer's warranty and we file that claim for you.
The Major Key guarantee
- 90 days on our labour, on every job. Rekeys, lockouts, door adjustments, installations — residential or commercial, the same number either way. If something we did comes loose, sticks, or stops working the way we left it, we come back and put it right at no charge.
- MK-line smart locks — 2 years on the lock itself. If an MK-1, MK-2 or MK-3 we supplied gives you trouble inside two years, we come out, replace the unit and fit the new one free — the visit and the fitting included. Not a manufacturer's call centre, not a returns form. Us. This is the one place we guarantee the hardware, because it is the one lock we chose.
- Other locks we supply — Mul-T-Lock, Kwikset, Schlage, Master Lock — carry their manufacturer's warranty on the hardware, and we file that claim for you rather than handing you a phone number. Our labour on them is the 90-day baseline above.
- What none of it covers: damage, forced entry, or a lock that was sound when we left and has been attacked since.
What mortise conversion customers say
We had excellent service. Timothy, the Locksmith arrived within a half hour of phone call. He repaired two locks for us and new keys for our front door. I would definitely recommend his service and I would definitely call him again if I needed him
Geraldine M.Google review
Timothy from Major Key Locksmith was such a nice and honest guy. He did a great job rekeying the locks at my house in Hasbouck Heights. He explained how the keypad works and was so patient with me. He is a very polite and cleaned up after the job was done. Would definitely recommend him to my friends and family.
Ann M.Google review
Called Tim this morning problem with two anderson French doors locks one not locking one loose handle keeps falling off. Tim was great fast efficient and resolved both issues quickly. We are in north caldwell private home in essex county. Highly recommend Tim he comes out and does the work himself.
Rima N.Google review
Excellent service and attention to detail. Tim was able to troubleshoot a number of mechanical issues with competence and creativity. Got everything working smoothly and efficiently. Tech options explained clearly. Highly recommended!
Julie G.Google review
Those are real, and they are quoted exactly as written — but they are still five we chose. Read them where they live — unedited, in whatever order Google puts them, including any we would rather you skipped.
400+ reviews is not a handful of friends. It is nine years of doors.
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