Doorknob & Lock Replacement: A Homeowner's Guide
A loose knob that spins, a deadbolt you have to lift the door to throw, or a key that fights you every morning are all signs the hardware is worn or misaligned. Sometimes you just moved in and want to re-key every exterior door for peace of mind. Either way, a door that won't latch securely is both an annoyance and a security gap.
Replacing a knob or lock sounds like a two-screw job, but the part that makes it work long-term is fit. The backset (the distance from the door edge to the center of the bore hole) has to match the new hardware, the latch has to sit square in the door edge, and the strike plate on the frame has to line up with the bolt. When any of those are off, the lock binds, sticks, or fails to engage. A clean replacement gets all three right so the door closes with a light push and locks without a struggle.
How the job is done
- 1
Identify the hardware and backset
We confirm the door's thickness and measure the backset, usually 2-3/8 or 2-3/4 inches, so the new knob or deadbolt lines up with the existing bore. This avoids buying or installing a lock that won't reach the latch hole.
- 2
Remove the old hardware
The interior screws come out first, then the two halves of the knob, and finally the latch plate screws in the door edge. We inspect the bore holes for stripped wood or prior over-drilling while everything is open.
- 3
Fit and seat the new latch
The latch slides into the edge mortise with the bevel facing the door frame, and the faceplate is set flush so it doesn't catch. If the mortise is shallow or chewed up, we deepen or reinforce it before screwing down.
- 4
Install and connect the lockset
The exterior half goes on with its tailpiece or torque blade through the latch, then the interior half mates to it. We hand-test the turn before tightening so nothing binds against the spindle.
- 5
Align and adjust the strike plate
We mark where the bolt actually hits the frame, then position the strike plate so the latch drops cleanly into the pocket. On a door that's settled, the strike hole may need to be filed or relocated slightly.
- 6
Re-key or test the cylinder
For matched keys across the house, we re-key the cylinder to a single key, then cycle the lock several times locked and unlocked to confirm smooth operation.
What a pro checks
- A knob that feels loose after a year is usually undersized screws or a worn spindle, not always a full replacement.
- Salt air in coastal areas can corrode cheap exterior finishes; solid brass or a quality coated finish holds up far better.
- A common DIY mistake is installing the latch upside down so the bevel fights the frame and the door won't latch on the swing.
- If you can lock the deadbolt only by lifting the door, the door has sagged and the hinges or strike need attention, not the lock.
- Re-keying existing cylinders is often smarter than buying all-new locks when the hardware itself is in good shape.
- Exterior deadbolts should throw a full one-inch bolt; a half-thrown bolt offers little real security.
Let AZ Smart Fix handle it
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Frequently asked questions
Can I keep the same key for all my doors?
Yes, in most cases compatible cylinders can be re-keyed so a single key works every exterior door, as long as the lock brands and keyways are compatible. We confirm that before starting.
What's the difference between a knob, a lever, and a deadbolt?
A knob or lever is the everyday latching handle you turn to open the door; a deadbolt is a separate, stronger bolt with no spring that adds real security. Many exterior doors use a knob and a deadbolt together.
My door won't latch unless I slam it. Is the lock bad?
Usually not. That's almost always a strike plate that no longer lines up with the latch, often because the door or frame shifted. Re-aligning or moving the strike plate typically fixes it.
How much does it cost to replace a lock?
It depends on the type of hardware, how many doors, and whether re-keying or strike repair is involved. The simplest way to get an accurate number is to book a visit or request a quote.
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