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How to Measure UPVC Door Lock Mechanisms


When looking at how to measure a UPVC door lock mechanism, the first thing to do is look for a manufacturer. Have a look at the faceplate on the lock and check if there is a manufacturer’s name on there, such as GU or Schlosser. You can search our door locks by brand and use that as a point of reference.

Centre Case

There are three types of centre cases in UPVC that you should be aware of.

  • Latch and deadbolt – these are the most common type of centre case and the type shown in the above image.
  • Latch and hook – these have a hook in place of the deadbolt.
  • Latch only

When trying to identify or measure a multi-point door lock, there are two critical dimensions you need to know and two that are useful for identification. All measurements to measure a UPVC door lock mechanism should be taken in millimetres.

The critical dimensions are:

  • The PZ, which is measured from the centre of the spindle (follower) hole to the centre of the top diameter of the lock cylinder (barrel) hole. If there are two spindles, always measure from the top spindle hole.
  • The Backset dimension, measured from the front of the lock face plate to the centre of the spindle (follower) hole.

It’s also helpful to have access to the height and depth of the centre case when looking at looking at how to measure a UPVC door lock mechanism.

Locking Points

It’s important to note how many locking points your multi-point lock door has. There are five different types of locking points you might see, and you may have more than one type on your door – for example, you might have two hooks or two rollers.

Types of locking points (see the image above for reference):

  • Hook bolts
  • Deadbolts
  • Pin bolts
  • Roller or flat cams
  • Mushroom cams

Lock Case Operation

You should also work out what follower or spindle operation the centre case has.

  • Single, solid follower – there is a single spindle located on the centre case. To identify a solid follower, try to open the door from the outside by depressing the handle lever (with the door not locked by a key). If it opens, the lock has a solid follower.
  • Single, split follower – this also has a single spindle on the centre case, but with a split follower, you will not be able to open the door from the outside without a key.
  • Dual follower – two followers are on the centre case.
Lock Case Position

Lock Face Plate Details

Finally, you should note the details of the face plate on your lock. This typically means its width in millimetres, its colour and whether it is flat or U-rail.

For further assistance or if you aren’t sure how to measure a UPVC door lock mechanism, please get in touch with us today and our expert team will help you out. Simply fill in the multi-point lock identification PDF with as much accurate information as you can and send it to us at

Download the PDF

Have a look at our other help guides for more guidance, or check out the full range of door locks on our website.