Many doors contain small windows or vision lights. These windows can bring light and exterior views into the home and may also serve as a decorative function. Unfortunately, the glass in these windows is easily broken as people move in and out of the doors. While caution must always be used when working with glass, most homeowners can make these repairs themselves, as they require only basic tools.
Examine the frame around the broken glass. In a wooden door, the glass will be held in place using thin strips of wood known as "beads." On one side of the door, the beads will be built into the structure of the door. On the other, they are installed using small finish nails. You will only need to work on the side of the door with these nails. Do not attempt to remove or replace glass from the other side of the door.
Use a utility knife to gently cut around the edges of the wood beads. They may be caulked in place, or sealed with multiple coats of paint. Cut through this caulk or paint with your knife on both the inner and outer perimeter of the beads.
Slide a putty knife between the glass and the edge of the beads. If the window is not square, start with one of the two longer beads. Pry the wood trim carefully away from the window, working on only one piece at a time. Once all four pieces of wood have been removed, the glass will no longer be secured in place.
Remove the pieces of broken glass very carefully. Wrap them in newspaper and dispose of them safely.
Use your hammer and a pair of pliers to remove the nails from the wood beads. If they are scratched or damaged, consider painting or staining them to match the door before you reinstall them.
Measure the width and height of the opening. Buy a piece of tempered (safety) glass that is 1.5 mm (1/16 inch) smaller than this opening in both height and width. This added space is needed to provide clearance so you can install the glass without breaking it.
Place the glass into the opening and add a line of clear caulk or putty around the edges. Have a partner hold the glass in place as you secure it.
Reinstall the wood beads starting with the two shorter sides if applicable. Use finish nails to fasten the beads at a 45-degree angle. The nails should penetrate the wood around the glass, never the glass itself. Work carefully to avoid damage to the glass.