Large panes (over 3 feet in any direction), second-story windows, or historic stained glass are best left to professionals. Also, if the frame itself is rotted, you’ll need wood repair or replacement first.
Roll a thin “bed” of fresh glazing compound (about the diameter of a pencil) along the frame’s inner edge where the glass will sit. Press the new pane gently into place, pushing it against the putty bed. Insert glazing points every 6–8 inches around the perimeter—push them flat against the glass and into the wood using the broad side of your putty knife.
Allow the putty to cure for 7–14 days (check the manufacturer’s instructions). Do not paint immediately—most glazing compounds need to form a skin first. Once cured, paint over the putty and frame edge with exterior primer and paint. This seals the wood and protects the putty from weather. how to fix broken window pane
Before anything else, put on safety glasses and thick gloves. Broken glass is unpredictable. Carefully remove any large shards by hand, then use a putty knife to scrape out smaller fragments and old putty. Sweep or vacuum the area thoroughly—don’t forget the floor below.
These video guides offer visual demonstrations for different types of window frames, including wood and aluminum, to help you master the repair process: How to Replace a Broken Window Pane | Ask This Old House This Old House Large panes (over 3 feet in any direction),
Putty knife (stiff and flexible), pliers, utility knife, and a heat gun or blow dryer to soften old putty.
Measure the opening precisely—width and height at three spots each (top, middle, bottom; left, center, right). Use the smallest measurement. Subtract 1/8 inch from each dimension to allow for expansion. Take these numbers to a hardware store, where they can cut glass to size. For safety, ask for double-strength window glass (about 1/8 inch thick). Tempered glass is even better but requires professional cutting. Press the new pane gently into place, pushing
Leather work gloves, eye protection, long sleeves, and closed-toe shoes.
If your window is simply cracked—not shattered—you can sometimes avoid replacement. For small cracks, clean the glass, apply clear nail polish or specialized glass repair resin, and scrape off excess. But if the crack spans more than a few inches, or the glass is missing pieces, replacement is the only durable fix.