How to Replace Window Glass

Replacing the glass in a window will cost significantly less than a full replacement. Whether you’re dealing with broken glass or have noticed other issues like condensation build-up between the panes, a glass-only replacement is something most homeowners may be able to DIY.

We’ve created this step-by-step guide on how to replace window glass safely, from glass removal to pane installation. 

1. Measure the Pane Opening

Before diving into the removal process, make sure you precisely measure the correct size and dimensions of the existing window pane. You’ll want to start by measuring the full interior of the frame, from side to side, and then top to bottom. Once you’ve recorded those dimensions, subtract ⅛ of an inch from both the height and width. This will leave room for any natural contraction or expansion of the glass that may occur with seasonal change.

2. Choose Your Window Pane Replacement

Next, you’ll need to settle on the best type of replacement pane for your home. Depending on the age of the surrounding sash,  this may be a good time to upgrade to a more energy-efficient glass, like insulated or tempered. If you live in a historic home and are looking to repair a window while preserving its original value, we recommend investing in help from a professional specializing in restoration.

For those replacing a single pane in a multi-paned window, you’ll want to find a glass that’s compatible with the surrounding panes. Pay close attention to details such as:

  • Height and width of the pane
  • Thickness and depth
  • Color of the spacer between panes
  • Whether the inner pane is filled with gas
  • Any coating or tint

3. Remove the Broken Glass and Putty

Next comes the actual removal of the glass. Protect yourself with thick gloves, proper safety eyewear, and long sleeves in the event of any surprise breakage. Then, use duct tape to temporarily patch any cracks in the glass to prevent spreading or fallout while working with the pane. We recommend taping an asterisk-shape across the window the ensure the entire pane is secure.

You’ll want to start by lightly chipping away at some of the glazing beadwork that surrounds the pane with a flat chisel or utility knife. This will help loosen the pane from its original setting. With most of the glazing compound removed, you can then begin to gently tap on the glass with the blunt end of a tool, like the back of the putty knife, then slowly coax the glass out of the frame.

Because you’ve taped off the cracked areas of the window, the glass should come out in one or large pieces, held together by the tape, rather than in smaller shards. It can help to have another person on the other side of the window ready to catch the larger pieces so they don’t fall and shatter. Please recycle the old glass properly.

4. Clean and Prep the Window Frame

Once the broken pane is removed, you’re ready to start prepping the frame for reglazing. Use the same utility knife to scrape out any residual glazing compound from the interior of the sash. A wire brush can also help loosen any bits of leftover glass, paint, or dirt from the smaller crevices of the frame. If you’re replacing glass in a wood frame, we also recommend lightly sanding down the surrounding l-shaped grooves to bare wood.

5. Setting the Glass and New Glaze Application

After cleaning and priming the opening, with the help of a partner, proceed to set the new glass pane into the frame. Before glazing, you’ll need to use two glazier points on each side of the pane, for a total of eight, to hold the window in place. These points aid in extra support and will prevent the new pane from falling out should the putty eventually fail.

To seal the window, use a caulk gun to apply a thin and steady layer of your chosen glazing compound or putty around the entire perimeter of the window. Make sure that you apply the sealant at a 45-degree angle. This will help shed rainwater away from the windows rather than pooling in the grooves. Finally, come back with the putty knife to smooth the glazing compound.

6. Prime and Paint Window

Depending on the drying time indicated on the brand of putty you used, it can take anywhere from seven to 15 days to set before it can be painted over.  Prior to painting, you’ll want to remove any surface oils from the putty with a dry rag.

Placing painter’s tape just above where the putty’s top seam meets the glass can help you create cleaner lines as you paint. You’ll want to let some of the paint overlap with a bit of the glass for an additional seal on top of the putty. Primer isn’t always necessary when painting over putty, but we recommend a 2-in-1 exterior paint and primer for added protection from weathering.

When to Replace Window Panes

Aside from visible breaks or cracks in the glass, other instances that may warrant replacing a window pane include:

  • Obvious drafts of inflowing or outgoing heat and cool air
  • Excessive energy bills
  • Water leaks or condensation between panes

Whether or not you should just replace the glass in your windows or opt for a full replacement largely depends on the age of your window and if other aspects of the frame are affected. For example, if your windows are over 20 years old and you’re noticing a deterioration in the glazing as well as rot in the frame, you’re better off replacing the window as a whole. On the other hand, if your windows are only five years old and a crack is starting to spider across one of the panes but the window is in overall good condition otherwise, you’ll save money by just replacing the glass.

Cost to Replace Window Pane

On average, it costs around $250 to replace the glass in a window. Extra materials and tools can add anywhere from $70 to $150 to the total replacement cost if you opt for a DIY replacement.

Frequently Asked Questions

What is the difference between the window glass and window pane?

Window glass and window panes are essentially the same things. Panes could be considered the measured and cut form of window glass as opposed to material itself.

Do you need a license to replace a window?

No. You don’t need a license to replace a window, but we would recommend having some prior experience with window work, or at least a partner to assist you in the process before taking the DIY route. Proper safety equipment like gloves and eye protection are equally as important.

What is standard window glass thickness?

The standard measurement of window glass is 3/32 inches thick.

Does Home Depot replace window glass?

Yes. Home Depot does offer professional window glass replacement services.

Editorial Contributors
Meredith Kucik

Meredith Kucik

Meredith Kucik covers home warranties, company reviews, real estate, personal finance, and all things homeownership for House Method. She has published work in local and national media publications across the home services category, reaching various consumers from homebuyers to sellers to real estate professionals. Meredith graduated from the University of North Carolina at Wilmington in 2021 with a Bachelor of Fine Arts in Creative Writing.

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Lora Novak

Senior Editor

Lora Novak meticulously proofreads and edits all commercial content for Today’s Homeowner to guarantee that it contains the most up-to-date information. Lora brings over 12 years of writing, editing, and digital marketing expertise. She’s worked on thousands of articles related to heating, air conditioning, ventilation, roofing, plumbing, lawn/garden, pest control, insurance, and other general homeownership topics.

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