How to Replace Window Glass Quickly

A rogue baseball or heavy storm can shatter your window, leaving your home open to the elements. Fix it quickly with our helpful tips.

gray and white family room
Project Overview
  • Working Time: 3 hours
  • Total Time: 1 week
  • Skill Level: Intermediate

Window glass replacement of a broken single-glaze pane is messy and requires attention to detail, but with a bit of practice, you can learn to install the glass safely and make smooth glazing lines. Your technique will depend on what kind of window pane you have. A wood frame takes more steps to repair but allows you to maintain the vintage character of your home. A vinyl frame is likely from a new home and is a much easier job. A professional must produce double-glazed windowpanes; you can't cut them yourself.

In most cases, having a local hardware store or glass specialist cut the glass for you is best. Unless the pane is very small, order double-thick glass; single-thick glass breaks easily. Order shatter-resistant glass for a door, sidelight, or other high-traffic areas. Be sure to wear thick gloves, long clothing, and protective eyewear when handling shattered glass. Tiny, nearly invisible splinters can cause injury.

To seal the window, apply traditional glazing putty (also called glazing compound) with a putty knife. You can also buy glazing putty in a caulk tube, but applying it with a knife creates a tighter bond and a smoother surface once you get the hang of it. For double-glazed panes, sealing tape usually needs to be replaced. You can often reuse rubber gaskets, but only if they're unbroken and haven't dried out and become brittle. Caulking needs to be scraped away and replaced. Wood molding can usually be reused, but you may want to replace it with new molding. We have tips for window glass replacement and repairing and sealing the glass in all kinds of window frames below.

Related: Find a Local Pro to Repair Window Glass

What You'll Need

Equipment / Tools

  • 1 Tape measure
  • 1 Paint scraper
  • 1 Chisel
  • 1 Glazier's putty knife or standard putty knife
  • 1 Wire brush
  • 1 Heat gun
  • 1 Glass cutter

Materials

  • 1 Glass pane to fit
  • 1 Glazing points
  • 1 Glazing compound or putty
  • 1 Linseed oil

Instructions

  1. Remove Glass Shards

    Usually, you can replace glass while the sash is still in the frame, but it's easier to remove the frame and work on a table. While wearing protective clothing, wiggle and pull out the shards of glass. You may need to tap the glass with a hammer to create a new break line first.

    If the glass doesn't easily come out in pieces, apply a grid of duct tape to the pane. Then, use a heat gun and scraper or chisel to remove all the putty and points and pull the pane out in one piece.

  2. Remove Putty and Glazing

    Take care to remove all pieces of glass, putty, and metal glazing points. You may need to use a pull-type paint scraper or an old chisel. If you use a hammer, tap gently. The grooves where the new window will go must be completely smooth. A heat gun can help soften the old putty.

    Editor's tip:

    1. If a pane is secured with pieces of wood molding, pry the molding out with a small flat pry bar.
    2. Scrape away any old caulk, test the fit, and apply new silicone caulk.
    3. Press the pane into the caulk.

    When reinstalling the wood molding, make sure to angle the nails so they don't touch the glass.

  3. Prep Frame

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    Wire-brush the frame and vacuum or wipe with a slightly damp rag. Apply a coat of linseed oil to the rabbet; this helps the putty stick securely.

  4. Measure Pane

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    Carefully measure the height and width of the opening in at least two places. Order a piece of glass 1/8-inch shorter in each direction. Test-fit the pane before proceeding.

  5. Apply Putty

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    Roll a ball of glazing compound into a thin rope. Press it into the corner of the rabbet. Then use a putty knife to press it firmly into place, making a narrow bed of putty for the glass to rest against.

  6. Check Glass

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    Gently press the glass into the putty bed, checking that it lies flat against the rabbet in all places. Every 6 inches or so, press a glazing point into the wood; push gently against the glass as you go.

  7. Roll Putty

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    Roll a rope of putty about 3/4-inch thick. Aim for a fairly uniform diameter, but it doesn't need to be perfect.

  8. Apply Putty to Glass

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    Press the rope against the glass and the frame using your thumb. Using a rag to periodically apply linseed oil to a glazier's knife or putty knife, press again using swiping motions every inch or two.

  9. Smooth Putty

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    Working in the same direction and holding the knife at the correct angle so the putty will not be visible inside, press firmly and draw the knife along the line to smooth the putty.

  10. Finishing Touches

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    If the resulting putty has a series of slight ridges, smooth them by lightly wiping with your finger, working in the opposite direction as in step nine.

  11. Remove Stop

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    Use a putty knife or small flat pry bar to remove the vinyl stop. Work carefully to avoid cracking the stop. Remove the glass and order a new piece to fit.

  12. Replace Sealing Tape and Sealant

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    Test to see that the new pane will fit. Scrape away the old sealing tape and clean the surface with paint thinner. Cut pieces of sealing tape to fit precisely and press them into place on the rabbet. Right before installing the glass, spread a bead of silicone sealant onto the rabbet.

  13. Place Glass

    Carefully set the pane in place—you cannot adjust its position once it is set into the tape. Then, press the vinyl stop back into the frame to secure the glass to complete your window glass replacement.

    Editor's tip: If your pane is held in place with a rubber gasket, slip the gasket onto the edges of the glass, pressing firmly, so the gasket is tight at all points. Then set the pane into the frame. You may need to partially disassemble the frame first.

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