Changing a mortice window fastener

Changing a mortice window fastener is very straightforward and can totally revamp the look of your windows. However, before going out and buying new window fasteners, be aware that there are three common types, and you need to choose the right one for your type of window design. Mortice and wedge fasteners are used with windows where the casement (opening part) closes against the frame. Hook fasteners are used if the casement is flush with the frame when closed. Below is a typical situation for replacing a mortice fastener.

removing old window furniture 1. Remove the old window fastener and mortice plate. If possible, try to use the existing holes and mortice rebate for the new window furniture.
positioning new window furniture 2. Hold the new fastener in place to check whether the fixing positions align with the ones from the old fastener. Only drill new fixing holes if required.
fixing window fastener in place 3. Screw the fastener in place and check whether it will close into the existing mortice rebate. If necessary use a chisel to adjust the rebate hole size.
positioning mortice plate 4. Position the mortice plate. These can be recessed, or surface mounted (as shown here) depending on window design and preference.
securing plate in position 5. Secure the plate in place. Check that the window can be opened and closed smoothly. Fill any visible old holes with filler, sand smooth and paint.

Window fastener tips

  • Generally a window fastener is attached about halfway up the opening section on a casement. For very tall windows you may need to position two fasteners – one closer to the top of the window and one closer to the bottom.
  • UPVC windows are normally supplied with closing and locking mechanisms. However, with many designs it is still possible to change the handles – a necessity if they are broken. The key is being able to find and access the retaining screws that hold the handles in place. If they are accessible, you may be able to change them, which is much easier and cheaper than changing the complete window unit. Check that changing a window fastener doesn’t invalidate your guaranties.
  • Many retailers will sell fasteners with a hook and mortice so that you can use the hook or mortice plate depending on your window design.


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