How to Remove and Replace a Thermal Glass Pane in a Vinyl Window

If one of your kids mishit a baseball and has broken the thermal pane in one of your new vinyl replacement windows, then you will be pleased to learn this is a simple repair. Even if you have never replaced window glass before, you can complete this project and restore your window to all its glory in a very short period of time. 

To replace the thermal glass pane in your broken window, you need the following tools:

  • a small chisel
  • a utility knife
  • a razor blade
  • a tube of clear silicone caulk
  • a caulking gun

In addition to the above, you also need to have someone who can help you remove the glass so it doesn't break.

To replace the broken pane of glass, follow these steps:

Step 1: Use a Chisel to Remove the Glazing Stops

Using your small chisel, remove the four glazing stops around the interior of the window. First remove the sides and then the top and bottom.

Step 2: Measure Your Replacement Glass Pane Before Removing the Broken One

Before you start cutting out the broken glass pane, measure the replacement to ensure it is the correct size.

Step 3: Cut Out the Old Thermal Pane Glass

Using the blade on your utility knife, cut the glazing and caulking from around the outside of the glass pane. Have your helper hold the glass pane in place while you cut it out. Once everything has been cut, then push out the top of the panel and have your helper lift it out of the frame. 

Step 4: Clean the Window's Frame

Using your utility knife, cut out any remaining leftover caulking or glazing tape around the interior of the window.

Step 5: Apply a New Bead of Caulking Around the Empty Window Frame

Once the window frame is clean, the apply a new bead of caulking around the inside of the empty window frame. Replace any of the setting blocks you removed and hold them in place with a dab of caulking.

Step 6: Install the New Thermal Glass Pane and Install a Healing Bead of Caulking

To replace the thermal glass pane, make sure the low-argon sticker is facing towards the inside of your house and place the bottom of the glass pane in place. Tilt the top of the glass into place and apply a healing bead of caulking along the window's bottom and up a few inches on each side. The healing bead holds the glass pane in place. Run your finger along the healing bead to remove any excess caulking.

Step 7: Re-Install the Window's Glazing Stops

Once the new thermal pane has been installed and caulked, then you need to re-install the glazing stops. Install the horizontal stops at the bottom and top of the window first, then install the side glazing stops.

Step 8: Clean Any Caulking Off of the New Glass Pane

Finally, once you have the new thermal glass pane installed into your vinyl replacement window, then you should remove any excess caulking using a razor blade or mineral spirits. 


To learn more, contact Becky's  Glass Works.

About Me

Keeping Glass Clean

When we first moved into our new home, I loved the number of windows that we had. It felt like every single room was bright and open, and I loved looking outside. Unfortunately, as time went on, I realized that our windows were getting harder and harder to see through, since there was always a grime buildup on the windows. I knew that I wanted to change things, so I went through the house and started looking at the windows. I realized that they were old, etched, and severely damaged. After I replaced them, our home looked and felt new again. Check out this website to learn more about windows.