1, With the frame firmly fixed in place, close the door/window fully and remove the beads (The mitred plastic strips edged with rubber on the inside of the frame to be glazed) by using a ‘glazing shovel’ or Richard knife. Note their position in the frame to ensure they go back in the same place!

2, Starting in the bottom corner closest to the hinges, place a single black glazing packer in the horizontal and another packer in the vertical internal glazing channel, then do exactly the same in the diagonally opposite corner. Place them right in the corner.

3, Place two wedge packers on top of black glazing packer, (the bottom packer thick end in the corner, thin end furthest from the hinge and the upper one the opposite way round with the thin ends overlapping slightly)

4, Place the glass in the frame and centralise it. Don’t let go of it!

5, Place two wedge packers in the same formation as the bottom corner in the top corner between the glass and the black glazing packer.

6, Using two more packers do the same against the black glazing packer (Bottom corner closest to the hinges).

7, Squirt a blob of silicon between the glass and the black glazing packer (in the opposite vertical corner) and then place two wedge packers in the silicon. The silicon will stop the packers from slipping down the frame.

8, Working a little at a time, slide the upper of the two wedge packers against the lower wedge packer, (starting at the bottom corner closest to the hinges, Horizontal lower, then horizontal upper, then vertical lower then upper vertical) Keep tightening the packers up, until the glass is held tight in the frame. Do not let go of the glass just in case!

9, Open the door/window (still holding onto the glass) to check that the frame doesn’t catch on the outer frame. If it’s still catching, then the wedge packers in the horizontal areas need to be tightened some more!

10, When the door/window opens without infringement replace the beads (shorter ones first) with a soft faced Plastic glazing mallet.