How to Replace Broken Window Glass

Glass is the barrier between your home and the elements, and a broken pane is an immediate security and energy concern. While modern double-pane windows often require a professional replacement of the entire sealed unit, older single-pane windows with putty or wood glazing stops are perfect weekend projects that require nothing more than a bit of patience and the right tools. Successfully replacing a pane is all about precision in the cleanup. If you leave shards behind or fail to scrape the frame down to the bare wood, the new glass won't sit flush. A job well done leaves a window that is airtight, rattle-free, and indistinguishable from the original install.

1. Secure Shards First. Cover the floor with a heavy drop cloth to catch glass shards. Wear thick leather gloves and eye protection before removing the remaining large pieces of glass from the frame.
2. Strip Hardened Putty Clean. Use a heat gun on a low setting to soften the old, hardened putty. Carefully chip it away with a sharp wood chisel or a putty knife, being careful not to gouge the wood frame.
3. Free Metal Glazing Points. Once the putty is cleared, you will find small metal glazing points holding the glass in place. Pull these out using needle-nose pliers.
4. Measure Three, Prime Once. Measure the opening height and width, then subtract 1/8 inch from each dimension to allow for expansion. Sand the bare wood of the frame and apply a coat of exterior primer.
5. Seat Glass Into Compound Bed. Apply a thin line of fresh glazing compound around the perimeter of the frame. Press your new glass pane firmly into this 'bed' so it seats securely.
6. Smooth Putty to Perfection. Secure the glass with new glazing points every 6 inches. Apply a bead of glazing compound over the points, smoothing it with a putty knife at a 45-degree angle to shed water.