How to Replace Broken Glass in Aluminium Windows

Knowing how to replace broken glass in aluminium windows can save you time and money. While aluminium frames are durable, their glass panes can break due to accidents, weather, or age. This step-by-step guide shows you how to safely remove the damaged pane and install a new one without replacing the entire window.

When Should You Replace the Glass?

Replace the glass if you notice:

Cracks or shattering
Moisture inside a double-glazed unit (IGU)
Chips that compromise safety
Rattling or loose panes

🛠 If the aluminium frame is bent, corroded, or warped, a full window replacement may be needed.

Tools & Materials You’ll Need

Safety gloves and goggles
Measuring tape
Replacement glass pane (cut to size)
Utility knife
Flathead screwdriver or putty knife
Suction cups (for large panes)
Rubber glazing gaskets or glazing tape
Neutral-cure silicone (optional)
Rubber mallet

Step-by-Step: How to Replace Broken Glass in Aluminium Windows

✅ 1. Remove the Glazing Beads

Most aluminium windows use clip-in glazing beads to hold the glass.

Carefully insert a flat tool between the bead and the frame
Start from a corner and work along the edge
Gently pop the beads out without bending them
Set them aside in order for easy reinstallation

📌 In some systems, you may need to remove rubber gaskets first.

✅ 2. Remove the Broken Glass

Wear gloves and eye protection
Apply tape over the glass to reduce movement
Remove shards carefully and dispose of them safely
Clean the frame and check for leftover adhesive, debris, or broken spacer blocks

🧹 Vacuum the area to clear hidden splinters.

✅ 3. Measure the Glass Opening

Measure width and height bead-to-bead, then subtract 2–3 mm
Measure the thickness of the old pane
Order replacement glass—clear, tinted, frosted, or safety glass depending on your needs

✅ 4. Install the New Glass Pane

Place glazing tape or rubber setting blocks at the base
Insert the new pane gently using suction cups
Ensure it sits flat, with even gaps on all sides
For double-glazed units, be cautious not to damage the spacer seals

📌 If required, apply a bead of silicone around the edges for weather sealing.

✅ 5. Reinstall the Glazing Beads

Snap the longest bead in first (usually bottom or top)
Follow with side beads, then finish with the shortest one
Tap them in gently with a rubber mallet to ensure a snug fit

Check the glass for movement. If it rattles, you may need additional packers or sealant.

✅ 6. Clean and Inspect

Wipe down the frame and glass
Check for alignment and tightness
If you used silicone, allow 24 hours to cure before cleaning

Pro Tips for Aluminium Window Glass Replacement

Always use safety glass (laminated or toughened) in doors and low-level windows
Avoid over-tight fits—glass needs a small clearance to avoid stress fractures
Replace old or hardened gaskets to ensure long-term sealing
Don’t rush—beads can bend if forced

When to Call a Professional

Large glass panes or multi-panel windows
Difficult bead systems or commercial-grade aluminium frames
Replacing fogged double-glazed units
Windows at height or in hard-to-reach areas

Typical Costs in South Africa

Item	Estimated Cost (ZAR)
Single-pane clear glass	R150 – R400
Laminated safety glass	R800 – R2000
Double-glazed panel	R1500 – R3,000+
Labour (per pane)	R400 – R1200

Conclusion

Replacing broken glass in aluminium windows is a practical DIY project for those comfortable with tools, but it also requires attention to safety, precision, and proper materials. Whether you’re tackling a single cracked pane or upgrading several windows, knowing the correct steps—from removing the beads to measuring and installing new glass—can save time and money. However, for larger or more complex jobs, especially those involving toughened or double-glazed units, it’s always best to call a professional glazier.

By following the right process, you can restore the security, energy efficiency, and appearance of your windows—and enjoy peace of mind knowing the job was done properly.