Broken windows may not bring bad luck the way broken mirrors do, but they still cannot be ignored. A broken window in your garage door is not only a safety hazard, but it can signal to burglars that you are not concerned with the integrity of your home. Fortunately, replacing your broken window requires little more than the proper tools and a few hours of your time.

Contemporary style home in Bellevue
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How to Replace a Garage Door Window

Assess What Type of Window You Have

Before the year 2000, most garage windows were individual panes of glass held within frames that were usually made of wood. This made replacing a single pane of glass very simple. After the year 2000, many garage door windows started to be made of a single, long pane of glass held in place between two frames that are screwed together. If you have this newer type of window, it might make more sense to contact a professional.

If you decide to replace this type of window yourself, measure the height and width of the window and purchase a replacement. Remove the screws from the inside of the frame. Have a partner hold the frame on the outside of the door in place until the job is done. Remove the old pane and dispose of it safely. Set the new pane in place. Fit the inside frame in place and screw the two sides back together.

Remove the Broken Glass

Put on safety goggles and heavy gloves, and remove all of the broken glass from the window. Save the largest shard of glass. Use a putty knife to dig any smaller shards out of the window frame.

Measure the Window Frame

Measure the thickness of the glass shard you set aside, then dispose of it with the rest of the broken glass. Measure the height of the broken window's frame from top to bottom and the width of the frame's opening from side to side. Subtract 1/8 of an inch from each measurement. This is the size of the replacement pane you will need.

Consider asking for tempered or laminated glass, then you purchase the new pane. Tempered glass is four times stronger than regular glass, and it is designed to break into smooth shards rather than sharp points. Laminated glass is coated with a thin film of plastic on both sides, so it also resists breaking into sharp pieces.

Prepare the Window Frame

Remove the small, rectangular glazier's points that help hold the glass in its frame. Chip away any dried glazing compound and dried paint that may be present on the frame. If the putty is very hard to remove, soften it by coating it in linseed oil and letting the oil sit for at least one hour. Or use a blow dryer to heat it up a bit.

Lightly sand the frame with a medium-grit sandpaper. Go over the frame again with fine-grit sandpaper, then brush away all dust and debris. Apply a coat of paint primer to the bare frame and let it dry thoroughly.

Install the New Window Glass

Carefully apply glazing compound in a thick line along the inside edges of the frame. Fit the new pane of glass into the soft putty. Make sure it is seated properly. Gently push new glazier's points into the putty every 4 to 6 inches around the frame to hold it in place. Let the glazing compound dry according to the manufacturer's instructions. Paint the frame to match the rest of the window and let it dry thoroughly. Clean the window glass to remove any fingerprints and dust.