Do not be intimidated by broken or smashed window. It is not difficult to repair a home window and doing it yourself saves money. Basically, you need to be careful and accurate. Always try to remove the window frame when attempting the repair of a large home window. It is safer to work on a flat surface whenever possible. When it isn’t possible to remove the window, you can follow these steps to replace a window pane.
Repair a Home Window with the materials and tools: putty knife, pliers, gloves, screwdriver, Glazier’s points, glass and putty.
Secure the broken glass with tape to avoid accidents. If the glass is severely cracked or smashed, apply tape to the damaged area so that it does not fall out while you remove the putty. You want to avoid having broken glass bits stuck at the edges.
Scrape the outer putty from the home window. A window in a wooden frame is sealed with putty, or a stiff paste. The putty needs to be removed to get at the window and it is best removed with a chisel, putty knife or other similar tool. Divide the putty into small chunks rather than large sections. Taking too large of a section can cause the wood to splinter, and you are trying to repair a home window, not cause more damage.
Take out the broken pieces of glass. If the glass is shattered, put on protective work gloves and remove the glass, carefully, one piece at a time.
Pull out the glazier’s points, the small triangular shaped pieces of sheet metal. A glazier’s point is also called a sprig, and it is driven into the window frame to hold the glass in place. Use a flathead screwdriver to take out the stubborn points. Some windows use slats, or wooden pieces instead or glazier’s points, you’ll want to pry these out carefully.
Remove the bedding putty, the thin layer of putty the glass was set upon during installation. This layer is the toughest to remove, so chisel slowly and carefully. A heat gun works well to soften the putty so that it will pull away. Hold the heat gun in one hand and follow with a chisel in the other hand. Do not apply a heat gun to old putty or a wooden window for an extended period of time as it may pose a fire hazard. Sand any rough spots until all traces of putty are clean.
Measure the window. From the inside, you measure the length from the bottom edge to the top edge and the width from the side to side. If you plan to repair the lower sash, measure from the check rail to the lower rail.
Go to the local hardware store or other shop that provides glass to repair a home window. Order glass that is slightly smaller than the dimensions of the frame. You will need some room to work with. A good rule of thumb is to go 1/8 inch smaller than your window measurements.
Prepare the frame. You can brush oil based primer to the frame before installation to seal the frame and to prevent the glazing putty from shrinking, which helps it last longer. Do check the manufacturer’s instructions prior to application though, including drying time.
Apply a thin layer of putty to the frame to bed the glass with a glazing knife. It functions like a cushion and keeps air from escaping. Just make sure the glazing is flat and even.
Install the new glass. Set the window glass in place carefully, but press it down firmly.
Tamp new glazier’s points along each side of the frame with a screwdriver to hold the new window in place. Place the points 8 inches apart for a large window. Use 2 points per side, positioning them 2 inches away from each corner for a small window.
Seal the window with putty. Knead the putty until it is soft and pliable then shape into long thin strips. Press the putty into the frame against the glass on all sides. Smooth out the putty with a scraper or knife. Make a beveled edge by holding the tool at a 45 degree angle. You may have to go back over sections of putty that come out of the frame or appear too thin. Scrape and trim excess putty.
Follow similar steps to repair a home window with an aluminum frame. Instead of removing the putty, you want to pull out the rubber gasket that holds the glass in place. You also want to have the glass cut 1/32 of an inch smaller than your window measurements and replace the gasket upon install.
Storey, John, Martha Storey, and Deborah Burns. Storey’s Basic Country Skills: A Practical Guide to Self-Reliance. Storey Publishing, 1999. Print.