How to Replace a Broken Window Pane
A broken window is a security and weather problem that should be addressed within 24–48 hours. Single-pane glass replacement is a manageable DIY project. Double-pane insulated glass units (IGUs) are more complex and often require a professional — though the cost is much lower than replacing the whole window frame.
Likely Causes
- 1Impact from projectile (ball, hail, branch)
- 2Thermal stress fracture (extreme temperature change)
- 3Frame shift or settling putting pressure on glass
- 4Failed seal in double-pane unit (fogging between panes)
High urgency — broken glass is a safety hazard and leaves the home exposed to weather and security risks.
How to Fix It: Step by Step
- 1Secure the area and remove broken glass safely
Wear heavy leather gloves and eye protection. Score loose pieces before removing them. Score the perimeter with a glass cutter and gently tap to break larger pieces into manageable sections.
- 2Apply a temporary fix
Cover the opening with heavy plastic sheeting and tape it inside and outside. This keeps weather and animals out while you arrange the permanent repair.
- 3Measure the opening
Measure the inside dimensions of the frame (height × width). For a single-pane replacement, order glass cut 1/8 inch smaller in each dimension to allow for glazing compound.
- 4Remove old glazing compound and glazing points (single pane)
Use a putty knife and heat gun to soften old glazing. Remove the metal glazing points with pliers.
- 5Install new glass
Apply a thin bed of glazing compound around the frame rabbet. Press the new glass in. Insert new glazing points every 6–8 inches. Apply and tool the outer glazing compound at a 45-degree angle.
- 6Paint over the glazing when cured
Allow the glazing compound to skin over (1–2 days). Paint over the joint with exterior paint to seal and protect it.
Materials & Tools Needed
Warning Signs It's Getting Worse
- ⚠Frame around the window is rotting or soft
- ⚠Window is in a bathroom, shower, or within 18 inches of the floor (safety glass required by code)
- ⚠Cracks are spreading from the break point
When to Call a Professional
Call a glass company for double-pane IGU replacement (requires specialty equipment), large panes over 20 square feet, safety glass (tempered or laminated) required by code, or any window where the frame itself is damaged.
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