Mortice locks · explained · Manchester
The lock in your door is probably older than your car. Keep it.
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- Service £40-70
- BS3621 fitted £85-140
- Keys cut to the lock
- 30-60 min
Manchester has streets and streets of Victorian and Edwardian housing, and a remarkable number of those front doors still have their original mortice lock. People replace them constantly. Most of them did not need to.
What a mortice lock is
The name is the fitting, not the mechanism. A mortice is the rectangular pocket chiselled into the edge of a door; a mortice lock is the one that lives inside it. Everything sits within the timber, which is why only the faceplate and the keyhole show.
Inside is a stack of levers: flat, shaped plates, each with a slot. The right key lifts every lever to exactly the right height at once, the slots line up, and a stump on the bolt can pass through. Wrong key, one lever at the wrong height, nothing moves.
Sashlock or deadlock
Deadlock
Bolt only, key operated. No handle, no latch. Usually the second lock on a front door, above or below the nightlatch. This is the one insurers mean.
Sashlock
Deadbolt plus a sprung latch and handles. One unit doing both jobs. Common on back doors and internal doors.
2, 3 and 5 lever
More levers means more combinations and more work to pick. A 2-lever lock has a genuinely small number of possible keys and belongs on a shed. Five is the practical standard for an external door.
But 5-lever does not mean BS3621. The standard tests drilling, picking and forcing, and plenty of 5-lever locks were never submitted. If your insurer asks for BS3621, only the Kitemark stamped on the faceplate counts. See BS3621 explained.
Why they seize, and why that is good news
A mortice lock that has stopped turning has almost always not broken. It has filled up.
A century of dust, plus whatever oil somebody squirted in during the 1980s which has since gone to varnish, plus rust from a door that has been rained on for a hundred years. The levers cannot lift cleanly. The key feels gritty, then stiff, then it will not turn at all.
That strips, cleans and services for £40-70. Replacing it costs £85-140 and usually gets you something built to a lower standard, in a door that was cut for the original. We replace when the body is cracked, the levers are actually broken, or your insurer requires a standard that did not exist when your lock was made.
Keys: no kiosk can help you
Lever locks predate standard key profiles. A key-cutting machine in a shopping centre has no blank for it and no way to read it. Copies have to be cut to the lock.
- One working key: we copy against the lock, £25-55
- No key at all: we remove it, read the levers, cut to the mechanism
- Both cheaper than replacing a hundred-year-old lock
Don't force it
A key that resists in a mortice lock is telling you the levers are not lifting. Turning harder does not persuade them. It snaps the key, inside the lock, and now you are paying for an extraction and possibly the replacement you were trying to avoid.
Lock repair · Broken key extraction · Rim locks and nightlatches
Questions people actually ask
My mortice lock has seized. Do I need a new one?
Usually not. A mortice lock that has stopped turning has nearly always filled up rather than broken: a century of dust, old oil that has gone to varnish, and rust from a door that has been rained on since it was hung. The levers cannot lift cleanly, so the key feels gritty, then stiff, then it stops. Stripping, cleaning and re-oiling it costs £40 to £70 and gives you back a lock built to a standard modern replacements often do not reach. We replace when the body is cracked, when levers are genuinely broken, or when your insurer requires BS3621 and yours predates it.
Is a 5-lever mortice lock the same as BS3621?
No, and this catches people out constantly. Five levers describes the mechanism. BS3621 describes a test the lock passed, covering drilling, picking and forcing, and requiring the lock to be key operated from both sides. Plenty of 5-lever locks were never submitted for testing and are not BS3621. The only thing that counts is the Kitemark stamped on the faceplate on the edge of the door. If it is not stamped there, your insurer will not accept it, however many levers it has.
Can a shop cut a key for my mortice lock?
No. Lever mortice locks predate standard key profiles, so a key-cutting machine in a shopping centre has no blank for it and no way to read the bitting. Copies have to be cut to the lock itself. If you still have one working key we can copy it against the lock for £25 to £55. If you have no key at all, we take the lock off, read the levers and cut to the mechanism, which takes longer but saves the lock. Both are cheaper than replacing a hundred-year-old lock with a modern one.
What's the difference between a mortice deadlock and a sashlock?
A deadlock is a bolt and nothing else, thrown by the key, with no handle and no latch. It is normally the second lock on a front door, sitting above or below the nightlatch, and it is the one insurance policies mean when they say BS3621. A sashlock combines that deadbolt with a sprung latch and a pair of handles, so one unit both holds the door shut and locks it. Sashlocks are common on back doors and internal doors. Same lever mechanism inside, different job.
My key turns halfway and stops. What's wrong?
One or more levers is not lifting to the right height, which usually means dirt, a worn key, or a bolt binding because the door has dropped and the frame has moved. Do not force it. A key that meets resistance in a lever lock is not going to be persuaded by more effort, it is going to snap, and a snapped key inside a mortice lock turns a £40 service into an extraction plus possibly the replacement you were trying to avoid. Try lifting the door slightly on the handle first, in case it is alignment. If it still resists, stop.