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> > Understanding Mortice Locks and Latches

Understanding Mortice Locks and Latches


The Period Ironmonger now stocks a wide range of Architectural 3 and 5 Lever Mortice Locks, Mortice Bathroom Locks and Mortice Latches, so we have decided to explain the terminology and describe the parts of the mortice lock to give you an idea of the things you need to consider when purchasing one.


A mortice lock or latch is fitted inside your door so the only visible part is the ‘outer forend’ with the latchbolt and deadbolt protruding from it.

The image on the right shows a Sashlock, these locks have two bolts, the latchbolt and deadbolt, the latchbolt is operated by a lever mechanism using either a door knob or lever handle and the deadbolt is operated using a key.

The main consideration when purchasing a mortice lock is do you want to use lever handles or door knobs when the lock is fitted. This will normally determine the Backset (B), which will ultimately let you know the size of the aperture required in the door to house the Lockcase (A).

For Door Knobs

Generally you will need a Backset of at least 75mm so that the door knobs will turn properly and you do not catch your knuckles on the door frame and striker plate – this means you should look for a lockcase that is at least 100mm.

For Lever Handles

With lever handles, usually a smaller backset is preferable, this is because the handle naturally takes your hand away from the frame and you wouldn’t want to have the handles set too far away from the edge of the door. So you will be looking for a lockcase between 60 – 80mm.

Most of the time locks are replaced alongside house renovation or house building, so there may well be a builder involved in the project to offer some advice. If you are in any doubt as to what you require please give us a ring and we will be glad to help you.

Browse our full range of Mortice Locks.