How to Fix a Broken Window

  • 01 of 07


    A man fixing a broken window
    Henry Arden / Getty Images

    All it takes is an errant baseball, a rock from a lawnmower, or a misguided bird to break the glass in a window. Occasional glass breakage is a normal part of owning windows. Broken windows require a repair call from a glazier or, more expensively, a visit from a window company to replace the entire sash.

    Fortunately, though, it is relatively easy to fix broken glass in a single-pane window. You just need a few simple tools and materials, some of which you may already have on hand. Other materials are easily obtainable at most home centers or hardware stores.

    Safety Considerations

    Working with glass is dangerous. Be sure to always wear safety glasses and thick gloves.

    Project Limitations

    This procedure works on single-pane, unsealed glass windows. If you have an older house that has not been updated, you might have single-pane windows. If you have double- or triple-pane windows (often called thermal or insulated windows), these need to be replaced by a professional. You can determine if you have multiple-pane windows by shining a light on the window from the inside while it is dark outdoors. If the window has multiple panes, the light reflection will be repeated. For example, on double-pane windows, two reflections will show up, one next to the other.

    Project Metrics

    • Working Time: 60 minutes
    • Total Time: 90 minutes
    • Skill Level: Beginner
    • Materials Cost: $10 to $30

    Tools and Supplies You Will Need

    • Thick leather work gloves
    • Safety glasses
    • Putty knife
    • Wood chisel or razor scraper
    • Fine-grit sandpaper
    • Linseed oil or clear wood sealer
    • Paintbrush
    • Tape measure
    • Replacement glass cut to size
    • Pencil (optional)
    • Metal straightedge (optional)
    • Glass cutter (optional)
    • Glazier's points
    • Glazing compound (putty)
    • Exterior-grade paint
    • Rubber mallet


    Before starting this project, it is important to understand how a single-pane window pane is fastened into the frame. If you have ever worked with glass photo frames that have bendable metal stays in the back, reglazing a single-pane window is similar. Instead of metal stays, the single-pane window uses metal triangles called glazier's points. These tiny metal triangles are essentially the nails that hold the glass to the wood. These points are later covered up with glazing compound and are no longer visible.

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  • 02 of 07

    Remove the Broken Glass and Clean the Frame

    A man preparing a new window
    Susanne Walstrom / Getty Images

    Using a putty knife, pry up the glazing compound. It should come off in large chunks. Then, as needed, use the putty knife, pliers, or a thin flat-head screwdriver to remove the old glazier's points. Wearing eye protection and with thick gloves, remove all of the broken glass. Discard the glass and old glazier's points.

    Using a chisel or razor scraper, scrape down the L-channel section of the frame from which you removed the compound and glazier's points. Be careful not to gouge the wood. Sand the wood smooth with fine-grit sandpaper, then seal any bare wood with linseed oil or clear wood sealer applied with a paintbrush.

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  • 03 of 07

    Measure the Frame and Buy the Glass

    A man carefully cutting glass with tools
    Wicki58 / Getty Images

    Measure and cut the new window glass to size. Measure the width and height of the window opening, using a tape measure and measuring to the outside edges of the L-channels. Subtract 1/8-inch from each measurement to use as the glass size.

    It is always easiest if you can have the glass cut for you at a hardware store or home center.

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  • 04 of 07

    Cut Glass to Size by Yourself (Optional)

    Hands applying pliers to glass
    Wicki58 / Getty Images

    Alternatively, to cut the glass yourself, place the glass on a clean, flat work surface. Make marks for the cutting line with a permanent marker. Place a metal straightedge on the mark and score the cutting line onto the glass with a glass cutter. A glass cutter has a small metal wheel for scoring the glass. Run the cutter along the straightedge while pressing the wheel down firmly. Make only one pass with the cutter.

    Be sure to wear safety glasses and gloves for this step. Slide the glass along your work surface so that the scribed line on the glass is aligned with the edge of the surface. Holding the main portion of the glass with one hand, use the other hand to push down sharply on the waste portion of the glass to snap it along the scored line.

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  • 05 of 07

    Set the Glass in Glazier's Compound

    A hand removing glazier putty with a scraper
    eag1e / Getty Images

    Roll out the glazing putty into long, thin ropes. Push the ropes into each L-channel of the window frame where the glass will rest. Place the glass into the frame, resting it in the putty. Using your putty knife, push two glazier's points into the bottom of the frame. If you need extra force, gently tap the handle of the putty knife with a rubber mallet to drive in the points.

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  • 06 of 07

    Finish Installing Glazier's Points

    A woman fixing glass with a putty knife
    Hero Images / Getty Images

    Install additional glazier's points, two per side for a total of eight glazier's points per window pane. Roll more glazing compound between your hands into thin ropes and force these ropes into each side of the frame. Force the rope farther into the L-channel with your putty knife held at a 45-degree angle.

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  • 07 of 07

    Let the Compound Cure, Then Paint

    A set of windows on a concrete wall
    emreogan / Getty Images

    Let the glazing compound dry and harden, following the manufacturer's recommended drying time. Paint the putty and any exposed wood with exterior-grade paint.