A window pane can get broken any number of ways; a miss-thrown baseball, a stone hurled the wrong direction or a tree branch being blown into the window. If this is a single-glazed wood sash, replacing it yourself will be fairly easy. Begin by removing the window sash and laying it on a flat surface such as a workbench.
Window pane preparation
For your safety wear a pair of gloves and safety glasses when removing the glass from the window pane. Small chips of glass can permanently damage your eyes. Cover the broken pane with a cloth or rag. Gently begin tapping the center of the covered pane with a hammer to loosen the broken pieces of glass. With your gloved hands or pliers gently wiggle the pieces that remain stuck in the putty.
Remove the old putty
With a painter’s tool or screwdriver pry the old putty loose. Gradually soften the putty that is still in place by using a heat gun and move it back and forth over the putty about an inch away from it. You will need patience in this step as some putty in old windows can become hard as cement, but it will soften. To make sure you don’t effect the pane next to the one you’re working on; hold a piece of metal flashing over the glass so the heat reflects off.
Prepare the rabbets
Pull the old metal glazing points out of the grooves in the sash, the rabbets, where the glass sits. You will need to sand and scrape the rabbets down to the bare wood. Use an exterior primer such as Behr primer and brush it onto the bare wood so it won’t shorten the life of the putty by taking the oil out of it. After the primer has dried, knead the putty until you reach a warm and pliant stage and completely fill the rabbets with the putty. You do not have to worry about being neat at this stage, push the putty in to make sure it has gone into the rabbet completely.
Place the glass
Using the tips of your fingers, wiggle the window pane into the putty by applying even pressure. Continue to gently push the glass down until it is centered in the opening and about 1/8 inch of putty remains between the face of the glass and the rabbet. If you notice any voids under the glass, pull it out and start over beginning with adding more putty.
Set the points
Place a glaziers point at the center of each side of the window pane so it is flat on the glass. Fit the tip of the putty knife against the raised shoulders of the points. Apply a slight downward pressure as you gently rock the point from side to side until the point is embedded in the wood. Repeat this process on the other two sides. You can now clean off any excess putty by flipping the window over and scraping it off.
Your window is now ready to be replaced on the house. If you need window hardware for your window pane repair feel free to use the contact form below, we will identify your window parts for free and let you know if we have them in stock!