Broken glass? Here's how to fix a broken window

There are many reasons why windows break. The glass could crack from thermal stress or from something smashing into it. Whatever the cause, this kind of damage requires immediate attention. 

For this reason, it’s nifty to learn how to fix a broken window. This guide will walk you through everything you need to know, from tools you need to prepare to some quick fixes you can do to tide things over until a handyman arrives.

Tools you need for the job

Before you start repairs, make sure that you have the following tools and materials ready. 

• Work gloves

• Safety goggles

• New glass

• Putty knife 

• Wood chisel or razor scraper

• Paintbrush

• Tape measure

• Glazing compound or putty

• Hammer

• Glazier or glazing points

• Glass scraper

• Turpentine

• Linseed oil

How to fix a broken window pane

The tricky bit about a broken window pane is the glass. It’s a safety hazard and enough reason for you to start repairs right away.

Step 1: Measure and buy the glass

Measure the window from the outside edges of its L-channels. Then, subtract 3mm from each measurement to get the appropriate glass size. Buy the glass panels at your nearest hardware store.

The glass size needs to be smaller than the window frame to make it easier to install. This gives room for the glass to expand and contract.

Step 2: Clean up the window frame 

Put on your safety gloves and goggles for this next part. Take out any glass shards sticking out and dispose of these immediately.

Next, scrape the hardened glazing compound or putty around the glass. The putty will be dry and brittle, causing it to come off in large chunks.

Then, pry the old glazing points open using either a putty knife, pliers, or a thin flathead screwdriver. Glazing points are the tiny fasteners embedded into the wood, holding the glass in place. Once the glazing points are out, you can take out all the broken glass carefully. 

Clean the inside of the frame by scraping it down with a chisel. Sand down the wood using fine sandpaper if necessary. 

Using your paintbrush, coat the wooden frame with linseed oil. This keeps the window frame from drying and cracking the new glazing compound.

Step 3: Mount the new glass

Take a ball of putty and knead it into your hands to soften it. Then, line about 3mm of putty along the edge of the window frame and press it down. This becomes the bed that the new glass will rest on.

Gently press the new glass into the bed of putty. Secure it in place using the glazing points found every 150mm (15cm) around the glass. Press the glazing points into the window frame using a stiffer putty knife or a chisel. 

Soften another batch of putty and roll it into a strand about 9.5mm thick. Press the putty along the edge of the window frame, shaping it into place as you work your way around the entire frame.  

Dip a clean putty knife into turpentine to smooth it out. Hold the knife at an angle and use the edge of the putty knife as a guide to making a neat bevelled edge. 

You can remove any extra putty as you go. Check if any putty is visible from inside the window when you look out. You can also scrape off putty that seeps out from the other side of the window.

Step 4: Cure the glaze, then paint!

Allow the glazing compound to completely dry. Drying times will depend on the manufacturer of the putty.

Then, paint the putty to match the wood. Let the paint dry. Afterwards, clean the glass from any fingerprints and dirt. 

And that’s it! You have your new window glass in place.

Temporary window fixes you can do

While waiting for your handyman to arrive, you can do some quick fixes to your window. This can prevent further damage from happening.

What’s easy about this is the materials are probably in your house already. Just remember that this is not a substitute for window repair!

For small cracks: Use glue or nail polish

Never leave a small crack on your window pane unattended. These can easily turn into a big crack. On top of that, they’re entry points for moisture.

What you’ll need:

• Glue or nail polish

• Paintbrush

• Toothbrush

• Razor blade

1. Using a toothbrush, dust away small pieces of broken glass outside the window crack. 

2. Paint the glue or nail polish over the small crack. The goal is to get it as deep into the crack as possible. You can take out any excess using the razor blade. Let the first coat dry.

3. Keep reapplying coats, waiting for each layer to dry in between until the crack has been filled.

For large cracks: Bring out the tape

The only way to fix a large crack is to replace the entire window pane. While waiting, do the following steps to prevent further damage.

What you’ll need:

• Toothbrush

• Clear packing tape

• Duct tape (optional)

1. Remove any glass debris around the crack using a toothbrush. This will prevent future injuries while you replace your window pane. 

2. Test if the glass is still strong by gently pressing down around the crack with the toothbrush. If it is strong, then apply clear packing tape on top. Make sure that the length of the tape is longer than the crack. Apply this on both sides of the crack. If it’s too brittle, take immediate action to have your window repaired.

3. To make sure the crack doesn’t get worse, you can add duct tape on top of the clear packing tape. 

When to call a professional

In most cases, you’ll need the support of a handyman to fix the crack in your window’s glass or replace your window pane. If you’ve had experience in doing a project similar to this before, or you’re up for the challenge, then the guide above should help you accomplish the task.

But if the damage to the window pane and its frame is too extensive, call in a professional to help. No temporary fix can take the place of a full window repair or window pane replacement. Luckily, you can hop on the Airtasker platform to post a task and connect with a Tasker who can fix your window right away.