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How to Install Glass in a Broken Window

Posted By admin On April 15, 2009 @ 2:03 pm In Building & Renovating | Comments Disabled

Many broken windows prompt an immediate call to the local glazier [1], but with a little care and proper preparation installing glass in a wooden window frame is a job that can be accomplished by any DIY enthusiast.


  • It is much easier to install glass if the window frame is removed from its casing. Place it flat on a workbench with the putty side of the glass uppermost and clamp securely to prevent movement.
  • Ensure that you take adequate precautions for your safety when setting out to fix a window – wear gloves and protective goggles.
  • Remove all broken glass from the frame and the scrape the frame free of all old putty with a putty knife. If the putty is difficult to remove it can be heated with a heat gun.
  • Remove any glazing points – the small metal pins inserted into the frame to hold the panes in place when installing glass.
  • Clean the window frame thoroughly with a wire brush.
  • Brush the surfaces that will hold the new putty with linseed oil and allow to dry for at least a day. This is an optional step when installing glass, but it will help increase the lifespan of your putty.


  • Measure the window frame to determine the dimensions of your replacement glass. To install glass safely allow a 3mm gap at the top and at one side for expansion. Have the glass cut to size by a glazier.
  • Place the new glass carefully into the frame. There should be a small ledge within the frame to hold the glass and prevent it falling through.
  • Insert two glazing points into each side of the window frame so that they hold the glass against the ledge. Push home with a flat tool.
  • Take a small ball of putty, work it in your hands until it is soft then roll it into a thin rope about 1cm thick.
  • Place this rope of putty against the first side of the window frame. Slide a putty knife along the putty at a 45 degree angle, using the frame as a guide. When using putty to fix a window your aim is to create a smooth bevel from glass to frame. Make sure that the glazing points are fully covered and that the putty does not extend beyond the width of the ledge (otherwise it will be visible from the other side of the window). Slide a flat knife along the glass to remove any excess putty.
  • Repeat for all sides of the frame and mitre the putty at the corners.
  • You have now successfully installed your glass and repaired your broken window. All that remains is to allow the putty to harden for between one and two weeks. The window can then be painted and re-hung.

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