5 Easy Steps To Fix Cracked Glass

Megan DeMatteo
Written by Megan DeMatteo
Updated July 30, 2021
A father and son sitting by the window reading their books
Tom Werner/DigitalVision via GettyImages

Use these five simple steps to repair cracked glass and DIY your own windowpane replacement

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Glass can easily chip or crack if you accidentally drop an object on it or knock a sharp item against it. Breaking a window is not unheard of during warm weather months when kids are outside playing catch or when hazardous objects like rogue tree branches get caught up in a windstorm.

Fortunately, cracked glass window repair is easy with some simple materials. If you have recently discovered a fissure in one of your home’s windows, consider the following do-it-yourself, step-by-step process to repair cracked glass.

  • Project difficulty score: 3/5

  • Time needed to complete the project: 1.5 hours

  • Tools and materials needed: Safety glasses, cut-resistant work gloves, paint scraper, paint blade, heat gun, caulk gun, paintbrush, wood filler, duct tape or painter’s tape, liquid PVC glaze, glass sheets, glass points

Is DIY Glass Repair Worth It?

Before you begin the repair process, you should first inspect the window and evaluate whether or not the glass is worth repairing in the first place. If the glass has suffered significant damage, you should turn it over to the hands of a local window glass repair pro.

DIYing a glass window repair will cost $50 to $200 depending on the size of your break and the quality of the materials you buy. Heat guns, the most expensive item on the supply list, range from $25 to $150. The costs vary based on region, but hiring a pro to come out to your home will probably run you at least $40–$70 per hour in labor.

If it's a less valuable piece of glass, such as a glass inlay or an insert in a coffee table, it may be worthwhile to replace it. A local glass repair or custom glass company should be able to provide you with a new piece of glass that matches the appearance, style and dimensions of the damaged one at a relatively low cost.

DIY Glass Chip or Window Crack Repair

A man brushes window frame
Cavan Images/Cavan via GettyImages

1. Prep the Area and Remove the Glass

Put on safety goggles and protective gloves, then tape an "X" shape in the middle of the glass you plan on removing (use the duct tape or blue painter’s tape). That way, if the glass shatters as you remove it, the tape will hold all the pieces together and reduce the risk of injury.

Remove the broken pane of glass—ideally in one fell swoop. With gloved hands, gently wiggle out any pieces that get stuck. You might have to use your heat gun to warm the putty or old glazing compound around the edges of the windowpane to loosen any final stubborn glass pieces. If need be, run the utility knife along the edge.

2. Purchase Replacement Glass

Write down the measurements of the space you need to replace. Ask the hardware store to cut the new piece of glass to order. Don’t forget to check the thickness of the old glass, in addition to height, width, and diameter (depending on the shape of the hole).

You’ll also need to know what type of glass the original pane was. If you don’t know, some easy observations can help give you and the hardware store a clue. If the glass broke into large, jagged pieces, it was likely annealed glass (the most common). However, if the glass crumbled into tiny pieces, that’s a clue it was safety glass.

Modern residential windows frequently use insulated glass units (IGUs) instead of single panes. You’ll know if your windows use IGUs because they are made from two panes of tempered glass separated by a space between them.

If your windows are made from specialty glass or IGUs, you’ll probably have to order a replacement from a glass manufacturer. 

3. Prep the Window Frame for Reglazing

Glaze is the putty-like substance that adheres the glass to the frame. Much like caulk, glaze has to be reapplied when installing new glass to ensure the glass is snug, insulated, and secure.

Still with your gloves on, clean the window track. Brush out any dirt, residue, or remaining bits of glass. You can use a wire brush and soften the old compound once more with a heat gun to loosen it. Scrape away the material using the putty knife.

You can also sand wooden frames at this step and even coat them with a sealer or stain. Putting a few coats of linseed oil around the frame might help the glazing last longer (but this is optional).

4. Squeeze on the Glaze and Set the Window Glass

This step might require an extra set of hands. With the caulking gun, apply a thin layer of window glazing compound into the grooves of the window frame, then set or slide the new window glass in until it’s secure. Glide the putty knife along the seams between the glass and the windowpane. You can also use your finger or a wet cloth. Apply more glaze as necessary—but stop if you notice the glaze swelling up too much.

You will have to wait a certain period of time after the repair is complete before you can remove the excess material. However, this varies depending on the type of kit you purchased, so make sure to consult the instructions.

5. Clean Up After Your Glass Repair

Sweep or vacuum up any leftover glass shards, brush away residual dust and wipe the fingerprints off your new glass pane—time to enjoy your new window.

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