Step-by-Step Guide: How to Replace Window Glass

• 19 May 2025

Broken, cracked, or misted window glass isn’t only about the appearance of your house—it can also impact energy efficiency, safety, and comfort. Though sometimes an entire window unit has to be replaced, homeowners are not always aware that most times you can replace the glass, and do it for a lot less money.

At Best Offer Glass, we’ve helped thousands of customers restore their windows to like-new functionality and appearance. If you’re considering doing it yourself or just want to know how to do it before hiring someone, here is a step-by-step guide on window glass replacement.

When To Replace Window Glass?

You do not always need to replace the entire window. Replacing just the glass will typically be your best option when:

• The glass is cracked, shattered, or broken.
• There is fog or condensation between double-pane glass (showing seal failure)
• You want to replace it with low-E or energy-efficient glass.
• The frame is intact, but the glass is broken.

Before starting any glass replacement project, assess the window to ensure the frame is still structurally sound. If the frame is rotted, warped, or damaged, replacing the entire window may be better.

Tools and Materials You’ll Need:

Safety gloves and goggles

• Measuring tape
• Utility knife or razor blade
• Putty knife
• Glazier’s points (for wood windows)
• Glazier’s putty or silicone sealant
• Replacement glass (cut to size)
• Heat gun (optional for old putty removal)
• Screwdriver (if applicable)
• Painter’s tape

Note: Always use protective gear. Broken glass is sharp and dangerous.

Step-By-Step Guide On How to Replace Window Glass

Step 1: Measure the Existing Glass

Before buying substitute glass, measure the existing pane. You will require:

• Measurable glass area width and height (excluding the frame)
• Glass thickness (usually 1/8″ or 3/32″ for single-pane)
• Measure to 1/16″. Subtract about 1/8″ from the height and width to leave space for expansion and fitting room.

If it’s a double-pane window, measure the entire insulated unit, or take the old unit to your local glass supplier—like Best Offer Glass—to have it cut to order.

Step 2: Remove the Broken Glass

If the glass is broken but otherwise intact, tape over the surface with the painter’s tape in an “X” pattern. This will prevent shards from falling when it is removed.

Carefully remove the broken glass with gloves and a utility knife. When removing older wood frames, use a putty knife to scrape out the old glazing putty and glazier’s points (the little metal clips holding the glass in place).

Dispose of the broken glass safely and thoroughly clean the area before proceeding to the next step.

Step 3: Prepare the Frame

After removing the old glass, check the frame for damage or old putty residue. If it is a wooden sash, scrape off all the old putty and sand the area lightly for a smooth surface.

You may have to remove and replace the vinyl glazing strips or the silicone seals for aluminum or vinyl windows. Wipe clean the frame with a damp cloth and allow it to dry.

Step 4: Dry-fit the New Glass

Before securing it into position, test-fit the new pane to confirm it is appropriately in the frame. It should slide on smoothly without getting stuck. If everything goes according to plan, gently remove it and set it aside.

Step 5: Installing the New Glass

For wood single-pane windows:

• Spread a thin bead of glazing sealant or putty along the inward lip of the frame.
• Push the new glass in gently.
• Use glazier’s points to hold the pane in place. Install them 6 inches apart with a putty knife.
• Install a smooth bead of putty around the perimeter, sloping a bit to drain water.
• Let the putty dry according to the manufacturer’s instructions before painting or sealing.

On vinyl or aluminum windows:

• Apply a bead of silicone sealant along the inside edge of the frame.
• Place the glass and press down lightly but hard in position.
• Replace the original glazing strips or trim.
• Allow the sealant to cure thoroughly before exposing the window to the weather.

Step 6: Clean and Inspect

Once the glass is installed and the putty or sealant is cured, gently wash the window with a non-ammonia glass cleaner. Inspect for gaps, leaks, or misaligned installation. You require a tight, clean seal to prevent future air or water intrusion.

Step 7: Touch-Up and Finishing

If your window’s frame is painted, you can now touch the area around the glass. New paint and primer for wooden frames help seal the putty and add longevity to the repair.

Do I Replace the Window Glass Myself or Hire Someone?

Replacing a broken single-pane glass in a wood sash is generally within the realm of DIYers. However, double-pane, tempered, or custom-cut insulated glass units (IGUs) are best left to the experts.

Benefits of expert glass replacement by Best Offer Glass include:

• Precise installation
• Energy-efficient glass solutions
• Warranty protection
• Quick turnaround with minimal disruption
• Proper sealing to prevent fogging or leaks

We have the equipment and expertise to handle any window glass replacement commercial or residential.

The Benefits of Window Glass Replacement

Regardless of whether it’s one window or several windows, replacing shattered or outdated glass has many advantages:

• More insulation and warmth
• Reduced noise pollution
• Reduced energy usage
• Increased home security
• Contemporary appearance and value

As a bonus, replacing glass instead of the whole window unit is generally less expensive, especially if your frames are still intact.

Call Best Offer Glass Today

Got a cracked or broken window? Don’t delay. Call Best Offer Glass today for a fast, affordable replacement of window glass. From a small crack to replacing whole insulated units, our professionals are here to help.