Project Guide

How to Replace Window Glass

Remove the Window
Man removing glass from a window.
  • Begin by using painter's tape or duct tape to tape an "X" shape in the middle of the glass to be removed. Make sure to cover any areas that are already shattered or cracked. The more surface you can cover with the tape, the better. This step will help prevent injury and reduce clean up if the glass breaks during the removal process, as the tape collects the glass pieces and holds them together.
  • Remove spring-loaded double-hung windows by pushing against the flexible vinyl channels to release the channel pins. Older double-hung window glass can be repaired while the window remains in the frame.
  • When figuring out how to replace glass in a double pane window, know that you can replace window glass without having to remove the entire window. 

Tip: Because they don't require putty and glass can be repaired while still in the frame, replacing glass in aluminum windows will be easier than replacing glass in a wood frame. 

Remove Putty and Clean the Frame
Person removing the window and putty.

Now that you have removed the broken glass, you need to prep the frame to be re-glazed. 

  • Using a wire brush, clean out any dirt and residue on and inside the window frame. 
  • Remove the metal glazing points from the frame and sand the L-shaped grooves to clean away the old paint and putty. 
  • Coat the bare wood with a sealer and let dry.
  • With traditional glazing, soften the old putty with a heat gun or torch, being careful not to scorch the wood. 
  • Scrape away the softened putty with a putty knife. 
  • On newer windows, simply pry out the vinyl glazing strip.
  • Remove the broken glass and metal glazing points from the frame, then sand the L-shaped grooves to clean away the old paint and putty. 
  • Coat the bare wood with a sealer and let dry.

Tip: For older windows, use a small brush and apply a few coats of linseed oil to the wood around the frame. Let the oil soak in as it will extend the life of the putty. 

Measure Glass
A person measuring glass.
  •  Before you replace broken window glass with a new piece, be sure to measure the height, width and opening of your pane. 
  • You should order your new glass at least 1/8 inches shorter in all directions. Always test fit the glass before setting with putty.  
Apply New Putty and Set Window
A person applies putty to the installed window glass.
  • Apply a thin layer of glazing compound in the primed grooves. 
  • With the help of a friend, set the new window in place. 
  • Press the new window glass lightly to bed it. 
  • Press in new glazing points every 10 inches with the tip of a putty knife.

Tip: If the putty is applied too thick, you will notice swelling and the putty will be visible around the pane. 

Apply Additional Glazing Compound
A person applies additional glazing compound.
  • Move the tube tip along the edge of the glass while steadily squeezing the trigger. 
  • Smooth the glazing with a wet finger or cloth. 
Paint the Window Frame
A person paints the window frame with white paint.

Take a look at your window frame to make sure it doesn't need a paint touch-up. If it does, follow these simple steps: 

  • Latex glazing can usually be painted the same day.  
  • Overlap the paint onto the glass by 1/16 inches to improve its weather seal.

Familiarizing yourself with the window frames in your home will make it much easier when it’s time to replace window glass. Simple differences are involved in how to replace glass in a vinyl frame vs. how to replace window glass in a metal frame. It is possible to get the job done yourself, but if you would rather leave it to a professional, our installation services can help.