A broken window is a security risk, an energy drain, and an eyesore — but replacing the glass yourself is simpler than most homeowners think and can save you hundreds of dollars over a professional repair.
Determine what you are dealing with. A single cracked pane in an older window is the easiest repair. A broken seal in a double-pane window causes foggy glass and requires full glass replacement. A stuck or painted-shut window just needs cleaning and lubrication. Identify your situation before buying materials.
Wear heavy leather gloves and safety glasses — this step is critical. Score around the edges of the broken pane with a utility knife to cut through any paint or glazing. Carefully push the broken pieces inward and collect them. Tape a large X across any remaining glass before removing it to prevent shattering. Wrap all glass in newspaper before disposing.
Use a stiff brush or putty knife to remove all old glazing compound, dried paint, and debris from the window channel. The channel must be completely clean for the new glass to seat properly. Sand any rough spots smooth and wipe with a damp cloth.
Measure the opening precisely — measure twice in both directions. Subtract 1/8 inch from each measurement so the glass has room to expand. Take your measurements to a hardware store or glass shop and have them cut a replacement pane. Single strength glass works for most small windows. Double strength for larger panes.
Apply a thin bead of glazing compound or window putty around the channel. Press the new glass firmly into place. Secure it with glazier's points — small metal tabs pushed into the frame every 6 inches using a putty knife. Apply another bead of glazing compound around the outside edge and smooth it at a 45 degree angle with a wet finger. Let cure for 24 hours before painting.
Take a photo of your window frame and the old glazing compound to the hardware store. The staff can match your glazing compound color and consistency exactly — saving you from buying the wrong product.
If your window frame is rotted, warped, or structurally damaged replace the entire window unit rather than just the glass. Double-pane and triple-pane insulated glass units must be ordered factory-sealed — this is not a DIY repair and requires a professional glazier.
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