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.

Jean Allsopp

When a windstorm whips through your neighborhood or a baseball crashes through a windowpane, it helps to know how to replace window glass. Follow our guide to learn how to repair your window and restore the look of your home.

Take photos to document the damage before you get started on any repair work. If you can’t repair the cracked panes right away, there are things you can do to prevent additional damage, vandalism, and exposure to the elements.

You can use a putty knife, pliers, or thick pieces of tape to scrape away big shards of glass. Be sure to wear thick gloves, long clothing, and protective eyewear when doing so—tiny, nearly invisible shards and splinters can cause injury. For a temporary fix that will work for spot damage, use nail polish or clear packaging tape on both sides of the broken glass. If there's extensive damage, you can board up your windows with plywood or big plastic sheets.

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 windowpane 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. You’ll have to hire a professional to make double-glazed windowpanes; you can't cut them yourself.

It’s usually best if you have a local hardware store or glass specialist cut the glass for you. 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. Remember that “impact-resistant glass” can still crack in a big storm, but the laminate will hold the windowpane together in the frame.

After you repair and seal the glass, treat yourself to a new look, with airy gauzy curtains or other updated window treatments.

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.

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:

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

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.

Carefully measure the height and width of the opening in at least two places. Order a piece of glass ⅛-inch shorter in each direction. Test-fit the pane before proceeding.

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.

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.

Roll a rope of putty about ¾-inch thick. Aim for a fairly uniform diameter, but it doesn't need to be perfect.

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.

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.

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.

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.

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.

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.

“Homeowners Handbook to Prepare for Natural Hazards.” National Oceanic and Atmospheric Administration, U.S. Department of Commerce.