A cracked window always seems to show up at the worst time, doesn’t it? Maybe something hit the glass. Maybe it’s been there a while and just got worse. Either way, now it’s all you can see when you walk past it. It nags at you. You keep thinking, Do I really need to replace the whole thing? Or, Can I fix this myself?
The good news is—yes, you can fix it. And in a lot of cases, you don’t have to spend a fortune or wait weeks for someone to come round. You just need to know what to use and how to go about it.
This post walks you through how to fix a cracked window at home. Whether you want to patch it up for now or do a proper repair, it’s all here. Easy to follow. No faff. Just clear answers and real steps that work.
Is it worth fixing a cracked window or should you replace it?
First off, let’s be real. Not every crack needs a full replacement. If it’s small—like a hairline or spider crack—and the frame’s still sound, then fixing it makes sense. It stops it getting worse, keeps your home safe, and saves money.
You’d want to replace the window if:
- The crack runs all the way through both panes of a double-glazed unit.
- The glass is loose, missing pieces, or rattling.
- The frame’s damaged or letting in water or draughts.
- It’s a safety issue or the crack is right where people could get hurt.
But if it’s a small to medium crack in just one pane, especially if the window’s double-glazed and only one side is cracked, you can fix or at least stabilise it.
Can you fix a window crack yourself?
Yes—you definitely can. There are a few ways to do it, depending on the size and type of crack. You can use clear glue, special window repair kits, epoxy, or even tape if it’s a short-term patch-up. The aim is to seal the crack to stop it spreading and to keep the glass solid.
If you’re dealing with a very old single-glazed window, repairing it is even easier. With double-glazing, the repair might be temporary, but it still buys you time before a full replacement.
What tools and materials do you need to fix a cracked window?
Before you start, you’ll want to get your tools and materials ready. Here’s what most people need:
- Clear epoxy or a glass repair resin (like the kind used for windscreens)
- Safety gloves and goggles
- A razor blade or craft knife
- Cotton buds or soft cloth
- Glass cleaner or rubbing alcohol
- Masking tape (optional)
If you’re using a resin repair kit, it will usually come with everything you need. Otherwise, you can find the items above at most DIY or hardware shops.
How do you prepare the window before the repair?
This part’s important. If the glass isn’t clean or the crack’s full of dirt, the repair won’t stick well.
Start by putting on your gloves and goggles. Then gently clean the cracked area using a glass cleaner or rubbing alcohol. Don’t press too hard—just enough to clear away dust, grime, or oils.
Once clean, let it dry fully. If you want, you can put a bit of masking tape below the crack to catch any drips from the resin or glue.
How do you seal a crack using clear epoxy or resin?
This is one of the best methods for small to medium cracks. It works by bonding the glass together, making the crack less visible and more stable.
- Open your epoxy or glass repair resin. If it comes in a syringe, it’s easier to apply.
- Slowly squeeze the resin into the crack. Let it flow in and fill the space. Don’t use too much—just enough to coat the crack.
- Use a razor blade or card edge to smooth out any excess.
- Let it sit and cure for the time recommended on the label—usually a few hours to overnight.
- Once dry, gently scrape any dried resin off the surface and polish the area with a soft cloth.
The crack might still be slightly visible, but it’ll be sealed and much less noticeable.
Can you use tape to cover a cracked window temporarily?
If you’re waiting for a glazier or you’re not ready to do the repair yet, you can cover the crack with clear packing tape or even masking tape on both sides of the glass. It doesn’t fix the crack but it holds the glass in place, stops it spreading, and protects against wind or bugs getting through.
This is only a short-term fix—but it’s better than leaving it open, especially in colder weather or high-traffic areas.
Can you fix double-glazed window cracks the same way?
Double-glazed windows are trickier. If only the inner or outer pane is cracked, you can still use resin or epoxy as a temporary fix. It’ll stop the crack spreading and help with heat retention. But over time, moisture might get into the sealed unit, which means it’ll eventually need replacing.
Still, patching the outer pane buys you time and keeps your home secure while you look into quotes or make arrangements for a new unit.
How do you know when a crack is getting worse?
Keep an eye on it over a few days. If the crack is growing or branching out, it means the stress on the glass is increasing. Changes in temperature, wind pressure, or even slamming nearby doors can make it worse.
If you spot it getting longer or if it starts to rattle or shift when touched, it’s time to act fast—either repair it properly or arrange a replacement.
What can cause a window to crack in the first place?
It’s not always obvious what started the crack. But here are some common causes:
- Sudden impact (like a ball, bird, or stone)
- Temperature stress (extreme heat or cold)
- Poor installation or frame stress
- Settling of the building structure
- Faults in the glass itself
Once cracked, the window’s integrity is weakened, so even a small bump or gust can make things worse.
Should you repair a cracked window or just replace the glass?
If you’re handy and the crack is minor, repairing it is a solid option. It’s quick, cheap, and effective.
But if:
- the crack is deep or long
- the glass moves when touched
- you can feel air or moisture getting through
- or you’re dealing with double-glazing and condensation starts forming inside the panes
…then it’s time to replace the glass—or even the full unit if needed.
Can you replace just one pane instead of the whole window?
Yes—especially with timber or older aluminium frames. A glazier can usually remove the cracked pane and install a new one without touching the rest of the window. This is often cheaper and quicker than full replacement.
For modern uPVC double-glazed units, though, the entire sealed unit is usually replaced as one.
Is fixing a cracked window safe?
If you follow basic safety steps, yes. Always wear gloves and goggles, even if the crack seems stable. Don’t press too hard on the glass. And never try to repair glass that’s badly shattered, bowing, or missing large pieces—get a professional in for that.
Can a repaired window still be energy-efficient?
That depends on the type of repair and the condition of the window. If it’s a minor crack and you seal it well, the loss of insulation is minimal—especially if only one pane is affected.
But if air is getting through, or if the sealed unit has failed (fogging between panes is a giveaway), then no repair will restore full energy efficiency. In those cases, replacement’s your best bet.
What’s the best way to make a cracked window look less obvious?
Once repaired, you can clean the area with glass polish to make the crack even harder to spot. Some people use a clear nail varnish top coat over small cracks for extra shine and concealment. Keep curtains or blinds down if you’re feeling self-conscious about the appearance, especially if the crack’s in a front-facing room.
Final thoughts: Why fixing a cracked window matters more than you think
It might seem small at first, but even a little crack can bring big problems if left alone. Water can seep in. Heat can leak out. Glass can shatter more easily than you think—especially when it’s already stressed.
Fixing a cracked window doesn’t just protect the glass. It protects your peace of mind. It keeps your home warmer, safer, and more secure. And when you do it yourself, it puts you in control—no waiting around, no costly call-outs, no stress.
So if you’re staring at a crack in the glass, don’t wait for it to spread. Clean it. Seal it. Watch it. And if it needs more than a patch, you’ll know exactly what to do next.
You’ve got this.
Glaziers Hitchin – Glaziers St Albans – Glaziers Northampton
