Can Cracked Window Glass Be Repaired or Does It Need Replacing?

Discovering a crack in your window can be frustrating, but it’s certainly not the end of the world.

A small crack can be repaired with a bit of DIY know-how, and Able glaziers can replace whole panes easily. But remember if you do have a crack, a repair is usually only a temporary fix. You should arrange for the window to be replaced as soon as you can.

Replacement is also necessary if the glass has shattered, if there’s condensation between panes, or if the window no longer insulates properly. The type of glazing and extent of damage will determine the best approach.

Should I get my cracked window replaced?

This depends on the size and severity of the crack. Small cracks (like hairline fractures or tiny chips) can often be stabilized or patched to stop them spreading and to keep the window safe as a temporary fix until. If it’s double glazing a cracked window usually means the insulation qualities have been compromised and the best solution is a replacement.

Some cracks are definitely beyond a simple fix, for example:

• If the crack is long, deep, or growing
• If the glass is shattered or has missing pieces (a safety hazard)
• If the crack runs through both panes of a double-glazed window
• If you feel a draft or see condensation through the crack (this indicates the seal is broken)

In these cases, a repair won’t restore the window’s strength or insulation. The only real solution is to replace the damaged glass pane or the entire unit, if it’s a double-glazed window. A temporary fix on a major crack is just buying time, and constant repair can cost more in the long run.

Can you fix a cracked window yourself?

If the crack is minor, you can often handle it yourself with the right materials. You can use a glass repair kit (like those for car windscreens), clear epoxy resin, or even super glue for a tiny chip. 

These will fill the crack and bond the glass together as a stop-gap solution. It reinforces the cracked glass for now and improves its appearance, but you will need to replace the glass. But, for a small crack, it’s a quick and cheap fix to extend the window’s life. Just be cautious.

If the crack is large or the glass feels unstable, call a professional glass repair service for a replacement.

If you need a super-quick fix, using clear tape can help. Simply press a strip of clear packing tape over the crack (on both sides of the glass if it’s single-glazed). This will hold the pieces together and keep the crack from getting worse. Tape also helps keep out drafts and rainwater. Remember, this is only a short-term solution while you arrange a proper replacement.

Note: Be careful not to press directly on the crack and don’t press too hard in case the glass is unstable. It may collapse. Call a professional if you’re unsure.

How do you seal a cracked glass pane with clear epoxy or resin?

Sealing a crack with clear epoxy or resin is an effective method to strengthen the glass. But it’s only a temporary fix, while you’re waiting for a replacement. Here’s a simple step-by-step guide:

Step 1

Fill the crack with resin: Use the epoxy or glass repair resin (often with a syringe applicator) to inject resin into the crack until it’s full. Don’t overfill it.

Step 2

Remove excess: While the resin is still wet, use a razor blade (held at a low angle) or a plastic card to gently scrape any excess resin off the surface so it’s flush with the glass.

Step 3

Let it cure: Allow the resin to dry and cure completely (follow the product instructions, usually a few hours or overnight).

Step 4

Clean up: Once cured, carefully scrape off any residual haze with the razor blade and polish the area with a clean cloth. The crack should be much less visible and is now sealed to prevent further spreading.

A crack generally means a compromise that needs professional attention at some point.

What causes window glass to crack?

Often, it’s a one-off event that causes a crack. Common causes include:

• Impact: A hard object (like a ball or tree branch) hitting the glass can crack or shatter it instantly.
• Thermal stress: Sudden temperature changes (for example, part of the window in hot sun and part in cold shade) can cause the glass to expand and contract unevenly, leading to a crack.
• Pressure or structural stress: High winds, the building settling, or warping window frames can put stress on the glass until it cracks.

Remember that any crack left will grow worse, so don’t delay action.

Can you replace just the cracked glass pane instead of the whole window?

If the window frame is in good shape, Able glaziers, for example, can remove the broken pane and install a new piece of glass of the same size. For modern double-glazed windows, they will typically replace the whole sealed glass unit without disturbing the frame. 

Note: The sealed unit is the glass unit that sits inside the frame but doesn’t include the frame

Only if the frame itself is damaged or very old should you consider getting a whole new window rather than just new glass. It may be more cost-effective in the long term.

Can a repaired window still be energy-efficient?

A tiny crack that you seal properly won’t significantly hurt your window’s insulation in the short term. However, if the crack is large or has broken the seal of a double-glazed unit (for instance, you see fog between the panes), then the window’s energy efficiency is compromised. In that case, no repair will fully restore the insulation. You’ll need to replace that glass unit to get back to optimal efficiency.

Why is it important to hire a certified glazier?

Hiring a certified glazier means the job is done properly. DIY might seem cheaper, but it can lead to more issues later, especially with double-glazed units or large panes of glass.

Certified glaziers are trained to handle all types of window glass. They’ll make sure the new glass fits perfectly, is sealed properly, and performs the way it should. That means no drafts, leaks, or rattling windows.

In many areas, replacing a window needs to meet building regulations. A certified glazier - one registered with FENSA or CERTASS - can self-certify the work, so you don’t need to worry about paperwork if you’re selling your home.

Reputable glaziers also offer warranties on both the glass and the installation.

Final thoughts on repairing cracked windows

Discovering a cracked window is never ideal, but you can sometimes patch up a cracked window and get more life out of it. But when a crack is beyond repair, a new pane or double-glazed unit is the best choice over a DIY repair.

If you’re unsure what to do, consider consulting a professional glazier. Getting expert advice means you won’t waste time or money on a fix that won’t hold. Don’t ignore window cracks. A quick repair now could save you a bigger headache later. But if the crack is too serious, replacing the glass will restore your window to good-as-new condition. But whatever happens, act fast.