How to Replace Window Glass

Replacing a single-pane window glass is a manageable DIY project that can save you hundreds of dollars compared to hiring a glazier. Here's a complete step-by-step guide.

When Can You DIY vs. When to Call a Glazier?

• DIY-friendly: Single-pane glass in wood frames, small to medium panes (under 24" in any dimension)
• Call a glazier: Double or triple-pane IGUs, tempered or safety glass, large panes, aluminum or vinyl frames with factory-sealed glass

What You'll Need

• Replacement glass (cut to size by hardware store)
• Glazing compound
• Glazier's points (small metal clips)
• Putty knife
• Heat gun or hair dryer
• Heavy leather gloves and safety glasses
• Primer and paint

• DAP '33' Window Glazing White 32oz — professional-grade glazing compound for bedding and sealing replacement glass in wood frames
• Glass Glue Ultra Strong Clear 100g — for sealing small gaps at glass edges after installation

Step 1: Remove the Sash (If Possible)

Working on a sash laid flat is much easier and safer than working on a vertical window. Remove the sash from the frame and lay it on a padded workbench.

Step 2: Remove the Broken Glass

Wearing heavy gloves and safety glasses, remove all broken glass pieces. Work from the top down. Wrap all broken glass in newspaper before disposal.

Step 3: Remove Old Glazing Compound

Use a heat gun or hair dryer to soften the old glazing compound, then scrape it out with a putty knife. Remove all old compound and glazier's points from the rabbet (the groove the glass sits in). Clean the rabbet thoroughly.

Step 4: Measure for New Glass

Measure the rabbet opening height and width. Subtract 1/8" from each dimension for clearance. Order glass cut to these dimensions from a hardware store or glass shop. Standard window glass is 3mm (single strength) or 4mm (double strength).

Step 5: Apply Bedding Compound

Apply a thin, even layer of glazing compound to the bottom of the rabbet on all four sides. This "beds" the glass and prevents water from getting under it.

Step 6: Set the Glass

Carefully set the new glass into the rabbet and press firmly and evenly. The bedding compound should squeeze out slightly around all edges. Center the glass with equal clearance on all sides.

Step 7: Install Glazier's Points

Push glazier's points into the wood frame every 6–8" around the perimeter using a putty knife. These hold the glass in place while the glazing compound cures.

Step 8: Apply Face Glazing

Apply glazing compound around all four edges of the glass, pressing firmly into the corner between the glass and the frame. Smooth at a 45-degree angle with a wet putty knife for a clean bevel. The glazing should contact both the glass and the wood frame.

Step 9: Let Cure, Then Paint

Let the glazing compound cure for at least 7 days before painting. Prime and paint over the glazing, lapping slightly onto the glass to create a weathertight seal.