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Period Door Knobs – What is a Backset Measurement?

January 24, 2014

Period Door Knob Sea Urchin
written by Vicki Bale
Period Door Knob Sea Urchin

Door Knob Showing correct backset


Whether you are considering changing your existing door furniture or you have a new door and you want some nice new period door knobs or door handles, there is a critical piece of information that you need to know – this is the backset measurement.

The backset measurement is the distance from the edge of the door to the centre of the hole which contains the spindle for the knobs or handles. The reason this measurement is critical is because it is different for door knobs and door handles.

Door Handles

We recommend using a mortise lock or latch which has a backset of about 44mm. Our Heavy Duty Latch 65mm (total cylinder length) is ideal as is the Heavy Duty Sash Lock, both with a backset of 44mm. If the backset goes too deep into the door the handles start to look too far away from the edge.

Door Knobs

These require a deeper backset than handles in order to prevent trapping fingers between the door knob and the door frame. It is very important! There is nothing worse and it is also a sign of poor building standards. We recommend using a mortise latch which has a backset of 81mm. Our Heavy Duty Latch 100mm (total cylinder length) is ideal. If you need to lock a door we recommend using the same latch with a Heavy Duty Deadlock. You may be able to get away with a slightly smaller backset measurement or you may need a slightly larger one if you are looking at large external door knobs.

Doors Currently in Use

Can I Replace Door Handles with Door Knobs?

We frequently have customers asking if they can replace their existing door handles with door knobs and the answer therefore is generally no. It may be that new latches can be put into the doors, but this can be a problem with the old screw and spindle holes and it can all become messy. It is worth cutting a paper template to the correct diameter of the knobs and then open and close the door checking if there is enough clearance for your fingers.

Can I replace Door Knobs with Door handles?

If you want to replace door knobs with door handles then this can be possible but the handles may look as if they are set too far back.

New Doors

If you are having new doors made, you can take your pick. It is then just a matter of having the appropriate door latches and locks put in.

For further assistance on this topic please give us a call on 01746 712450.

Images show the heavy duty latch (left) and the heavy duty lock (right).

Heavy Duty Door LatchHeavy Duty Sash Lock










Leave a comment


    John Cannizzaro says:

    I am making a door for a customer who wants a center pull knob. If the knob is fixed, how does the door latch? I know you would have a lockset in the normal place on the edge of the door–do you have to lock and unlock the door every time you open it? This is the first time I’ve been asked to install one of these. There are some very expensive interior mechanisms that use turning knob, but they are commercial and not very attractive. Interested to know what you usually do.

    John Cannizzaro
    Cannizzaro Custom Woodworking
    Greensboro, North Carolina, USA

    Vicki Bale says:

    Hello John
    The centre door knobs is fixed and bolted from the rear. To open and close the door you can have another pairs of knobs to the side with connecting latch. In the UK many people use Yale locks and night latches.

    We’re a group of volunteers and opening a new scheme in our
    community. Your website offered us with valuable info to work on.
    You have done an impressive job and our whole
    community will be grateful to you.

    Vicki Bale says:

    Thank you for your kind remarks. Good luck.