Lock Change and Replacement
Changing a lock is a fitting problem before it is a shopping problem — backset, bore and door thickness decide what can go on at all.
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A lock change is a hardware decision rather than a key decision. It is the right call when the body of the lock is worn through, when a door carries hardware too light for the work it is doing, or when you want a different function entirely: a keyed lever where a passage knob used to be, or a deadbolt with a thumbturn inside instead of a second keyway.
The awkward part is fit, not choice. Doors are bored to dimensions that are only mostly standard, and a lock that suits yours on paper can still sit wrong once the old one is off the door. Measuring before anything is ordered is what separates a straight swap from a morning spent enlarging holes.
The measurements that decide what fits
- Backset — the distance from the door edge to the centre of the bore. Residential doors come in two common backsets, and hardware set for the wrong one leaves the latch short or the handle crowding the frame.
- Bore diameter through the face of the door, plus the smaller cross bore through the edge that the latch body passes into.
- Door thickness. Most sets cover a range, but an older solid slab, or one with panelling added over it, can fall outside that range and need a longer spindle and screws.
- Handing, for anything with a lever. Hinge side and swing direction decide which way the lever points, and some designs reverse in the hand while others are built one way only.
- Bolt throw against strike depth. A new deadbolt is only as good as the pocket behind it, and a recess chiselled shallow for the old lock will stop the new bolt well short of home.
Useful to know before hardware is chosen
- Whether you are matching a finish used elsewhere in the house or starting from nothing.
- Whether the inside face should carry a thumbturn or a keyway, and who is in the house when that distinction matters.
- Whether the door is exterior, interior, or the one between a garage and living space, since the demands differ sharply.
- Whether the current lock was fitted after the door was built, which usually means non-standard holes.
- Whether the new hardware should share a key with the doors that are staying as they are.
If the locks turn smoothly and the only thing that changed is who holds a key, replacing hardware spends real effort on a problem that repinning already solves. see residential rekeying.
Common questions
Will a new lock cover the marks the old one left?
Usually, if you stay with a broadly similar style, because most residential trim rings sit within the same footprint. Going from a large decorative rose to a slim modern one exposes a ring of unpainted or unweathered door around it, which is easier to know beforehand than to discover afterwards.
Do the knob and the deadbolt have to be changed together?
Not mechanically — they are separate locks in separate holes and neither depends on the other. People pair them for finish matching, and because the deadbolt is the lock doing the real work, so a heavy new deadbolt sitting above a failing knob set is an odd place to stop.
What does a lock grade actually tell me?
Grading comes from cycle and strength testing, so a higher grade broadly means the lock survives more use and more abuse before something inside it gives. It says nothing at all about pick resistance, key control, or the quality of the door and frame the lock is mounted in.
Can new locks be matched to a key I already have?
Often, provided the new cylinder accepts the same blade profile. Where it does not, the alternative is keying the new hardware together and repinning the older doors to match it, which arrives at one key from the other direction.
Related locksmith services
Describe the lock or key problem
A short description of what happened gets the right tools on the vehicle.
Call (408) 418-0044