How To Fix Broken Window Pane File

Putty knife (stiff and flexible), pliers, utility knife, and a heat gun or blow dryer to soften old putty.

Replacing a broken window pane is a manageable DIY project that can save you the cost of a full professional installation. Whether you are dealing with a historic wood frame or a modern aluminum one, the key to a successful repair is careful preparation, accurate measurement, and safety. how to fix broken window pane

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. Putty knife (stiff and flexible), pliers, utility knife,

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. Large panes (over 3 feet in any direction),

Scrape the frame until it’s clean and smooth. Remove any old putty residue. If the wood is bare, brush on a thin coat of linseed oil—this prevents the new putty from drying out too fast and cracking. Let it soak in for 15 minutes.

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.

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