An errant baseball, a disoriented bird, a hailstorm — all can result in a broken windowpane, and for both safety and aesthetic reasons, this repair needs to go straight to the top of your to-do list.
However, replacing broken glass in a single-pane window requires some skill, patience and a good deal of caution. You may consider leaving this job to professionals, especially if the pane of glass is large.
Be Clear On What You Are Repairing
These repair instructions are narrowly targeted toward a certain type of window: a single-pane glass window.
Most windows today are now double-glazed or double-paned. Both are terms for windows that have two panes of glass, one in front of the other. Between the two panes is a void which is either air or filled with krypton or argon gas.
If you have one of these types of windows, you cannot use these repair instructions.
Repair Single-Pane Glass
First, some morale-boosting advice: do not be put off by the length of these instructions. It is fairly easy to repair a single-pane glass window.
Wear work gloves and safety glasses while completing the repair.
- Remove the broken shards of glass from the frame, one piece at a time, taking care to protect yourself from being cut by the razor-sharp edges. Even wearing gloves, don’t take any chances: Lay a towel over the glass and use that to help remove it, wiggling each piece out slowly. Save some shards to take to the store if you want to match the replacement glass more accurately.
- Wrap the broken glass in newspaper and dispose of it in a bag, box or other container.
- Measure the size of the window opening and subtract 1/16 to 1/8 of an inch from both the length and width when ordering a replacement pane. It is important to take exact measurements.
- If the frame is vinyl or metal, pull out the spring clips or vinyl splines with pliers or a screwdriver and skip to step 10.
- If the frame is wood, remove the old putty or glazing compound from the window using a putty knife or chisel. A heat gun will help soften the putty and make it easier to remove. Heat an area just before you scrape, removing a little at a time. Trying to remove too much at once can damage the frame.
- Using a pair of pliers, pull out the glazier’s points – the little metal triangles in the frame beneath the beads of putty that held the pane in place.
- Clean the area and lightly sand the frame. Use a small paintbrush to apply a coat of linseed oil to the frame. The oil will help the glazing compound stay pliable while you install the new pane of glass.
- Apply a thin layer of glazing compound around the frame with the glazing tool. The glazing compound should be the consistency of thick dough, which will provide good cushioning when you insert the new pane.
- Insert the replacement glass into the wood frame and press firmly. If the frame is vinyl or metal, insert the replacement glass and reinsert the spring clips or vinyl splines. Replace the spring clips if the old ones are damaged or corroded. Skip to step 13.
- Hold the pane in place and insert glazier’s points into the corner using the glazing tool.
- Insert glazier’s points every 4 inches around the glass and drive them into the wood with the glazing tool.
- Knead glazing compound into strips the thickness of a pencil. Place it around the edges of the newly installed pane of glass, pressing it into place between pane and frame with your fingers.
- Coat the blade of the glazing tool with linseed oil and smooth the glazing compound. Hold the tool at a 45-degree angle in a corner and slide it toward the opposite corner with one stroke. (The glazing compound should cover the glazier’s points, but be careful not to spread the glazing compound so it is visible in the windowpane.)
- Allow the glazing compound to cure for at least a week before painting.
Glass Repair Tips
- If you are removing broken shards from an especially large windowpane, consider removing the entire window frame and laying it flat. You can remove and replace the glass from the frame in this position to ensure greater control and safety.
- A glass store and most hardware stores can cut a new pane of glass for you to your size specifications.
- Make sure to let the window set for about 24 hours before raising or lowering it.
What You Need to Repair Glass
- Work gloves
- Safety glasses
- Old towel
- Newspaper and paper bag or box to dispose of broken glass
- Replacement glass
- Putty knife/chisel
- Heat gun
- Glazing compound
- Small paintbrush
- Linseed oil
- Glazing tool
- Spring clips (optional)
- Glazier’s points
- Fine grit sandpaper