How can I replace a broken window pane?

Short answer

Yes. Replacing a broken window pane is a manageable DIY project for most homeowners: remove the sash (if possible), safely clear the old glass and glazing, measure and fit a new pane slightly undersized, bed it in glazing putty or tape, secure with glazing points or stops, then finish and paint once cured. Below is a step-by-step guide for wooden single-pane windows, with notes for vinyl/aluminum and insulated double-pane units.

What you’ll need

• Safety gear: cut-resistant gloves, safety glasses, long sleeves, dust mask/respirator (P100 if lead paint is possible)
• Tools: utility knife, putty knife/scraper, glazing knife, small chisel, needle-nose pliers, hammer, heat gun (optional), oscillating multi-tool with scraper blade (optional), glass cutter (if cutting your own), tape measure, straightedge, caulk gun
• Materials: replacement glass (single strength 3/32" or double strength 1/8"), glazing putty (oil-based like DAP 33 or Sarco), glazing points, oil-based primer or boiled linseed oil, paint (exterior), painter’s tape, drop cloth/cardboard
• For metal/vinyl frames: glazing tape or silicone, plastic/wood setting blocks, replacement stops/beads if damaged

Approximate cost: $30–$80 for a small single pane; $120–$300+ for insulated glass units (IGUs). Time: 2–3 hours plus putty cure time.

Safety first

• Tape an “X” over cracked glass before removal to reduce shards. Lay a drop cloth to catch pieces.
• For homes built before 1978, paint may contain lead. Avoid dry-scraping; use a HEPA vacuum and wet methods, and follow EPA RRP practices.
• Wear eye and hand protection throughout. Work gently—force breaks glass and damages sash.

Step-by-step: Wooden sash with single-pane glass

1) Remove the sash (recommended)

• For double-hung windows, remove interior stops or tilt latches to take the sash to a bench. Working flat is safer and neater. If removal isn’t feasible, protect the sill and work in place.

2) Remove broken glass and old glazing

• Score painted edges with a utility knife.
• Carefully pluck out loose shards with pliers. Dispose in a rigid container.
• Warm old glazing with a heat gun on low to soften. Use a putty knife or chisel to lift out the glazing. Avoid scorching wood.
• Pull out glazing points with pliers.
• Scrape the rabbet (the recessed ledge) clean. Vacuum dust.

3) Seal bare wood

• Brush a light coat of boiled linseed oil or oil-based primer onto the rabbet. This keeps the wood from wicking oils out of the glazing and improves adhesion. Let it tack up.

4) Measure and order/cut glass

• Measure the rabbet-to-rabbet width and height, not the visible opening.

Order size = Rabbet width – 1/8" and Rabbet height – 1/8"
Glass thickness: up to ~24" small dimension = 3/32"; larger panes = 1/8"

• Dry-fit if you cut it yourself. It should drop in without force. If near doors, tub/shower, or very low to the floor, local code may require tempered/safety glazing—verify before ordering.

5) Bed the glass

• Roll a thin rope of glazing putty and press it into the rabbet to make a bedding layer.
• Set the pane into the bed and press gently until it seats uniformly. Clean squeeze-out on the interior with your knife.

6) Secure with glazing points

• Install glazing points every 6–8 inches around the perimeter (closer on small panes). Push them in flush with a putty knife or use a point driver. Do not overdrive.

7) Apply the finish glaze

• Knead putty until workable. Run a bead along the exterior, then tool it to a smooth 45° bevel from the glass to the outer sash edge. Aim for a straight line at the sightline.
• Lightly dip your knife in mineral spirits for smoother tooling if needed.

8) Cure and paint

• Allow putty to skin over per manufacturer directions (typically 5–7 days). Then paint the sash and putty with exterior paint, slightly lapping onto the glass by 1/16" to seal the joint.
• Reinstall the sash once the paint is dry to the touch.

Vinyl or aluminum windows (with snap-in stops)

• Pry off interior stops/beads carefully with a thin putty knife.
• Remove the broken glass and any glazing tape/silicone.
• Place 1/8" setting blocks at the bottom of the frame to support the glass.
• Apply glazing tape or a thin silicone bed to the frame. Set the glass squarely against the blocks.
• Reinstall stops in the same orientation. Tap gently with a rubber mallet. Do not bow the frame.

Insulated double-pane (IGU) units

• If you see fogging between panes or a spacer around the edge, you have an IGU. Replace the entire sealed unit; you cannot repair the seal.
• Measure overall width/height and thickness (including spacer). Many frames require specific gasket/stop systems. This is doable for experienced DIYers but often worth calling a glass shop—they’ll fabricate the unit and handle delicate stops.

Tips for best results

• Warm putty slightly or work it with your hands for easier tooling.
• Keep knives sharp; a glazing knife with a beveled edge makes clean lines.
• Use painter’s tape to outline the sightline for crisp putty and paint edges.
• On windy or cold days, let glass acclimate to room temp before installation to reduce stress cracks.

Common mistakes to avoid

• Ordering glass to the visible opening instead of rabbet size (leads to a too-large pane).
• Skipping the bedding putty—this causes rattles and water leaks.
• Not priming/sealing the rabbet; putty dries out and fails early.
• Painting before the putty skins, causing wrinkling or poor adhesion.
• Using high-heat settings on a heat gun and scorching wood or breaking adjacent glass.

When to call a professional

• Large panes, high or hard-to-access windows, or anything requiring scaffolding.
• Safety glazing requirements (tempered/laminated), e.g., near doors, stairs, bathrooms, or very low sills.
• Historic sashes you want to preserve with minimal damage.
• Complex aluminum/vinyl systems or sealed IGUs with proprietary stops.

With patience and the right tools, a single-pane replacement is a satisfying weekend fix that restores weather-tightness and appearance. For more complex frames or IGUs, partnering with a glass shop can save time and reduce risk while still letting you handle prep and painting yourself.