Tips For Repairing Broken Single Pane Windows

Repairing broken windows is an unfortunate reality of home ownership. For those of you with single-pane windows, the process of replacing the broken pane is pretty straightforward. If you are dealing with a large piece of glass, larger than you can handle comfortably, it is better to let a professional do the job rather than struggle to do it yourself. Glass can be dangerous, so use common sense when deciding what you can and can’t repair.

Tools and Materials For Repairing Windows

Glass repairs require heavy-duty gloves and protective goggles. Don’t skip this step or stint on quality when purchasing these items. You will also need a sturdy bag to put the shards of broken glass in as well as tape to hold cracked portions in place while you are preparing to remove them, caulk (sometimes called glazing compound or putty), a screwdriver, hammer, chisel, measuring tape, protective goggles, long-nosed pliers, paintbrush, primer, glazing points, linseed oil, towel, paper towels, single-edge razor tool, and a vacuum cleaner. Read also my article about 12 tools you always need around the house.

Remove the Old Broken Glass

While wearing gloves and goggles, remove loose pieces of glass and discard them by placing them in a heavy-duty paper bag. If the window is cracked but not broken, apply a grid of masking tape across the surface of the window with strips about three inches apart. Cover the window with a towel, and then hit it with a hammer just hard enough to break the glass. Carefully work the broken pieces free using needle nosed pliers if necessary. Sweep or vacuum the area thoroughly.

Clean the Window Frame

Once all the glass has been removed, remove all glazing points (small aluminum supports) and pry or scrape the old caulk from around the window frame. For stubborn patches, use the corner of your putty knife or a chisel. Sometimes a heat gun is used to loosen old calk. A few minutes’ effort will tell you if this extra step is necessary.

Lubricate the Window Frame

Once all of the glass and old caulk has been removed, lubricate the groove with linseed oil. This will extend the life of your caulk by helping to keep it from drying and cracking prematurely.

Prepare the Glass

Measure your frame, and either purchase or cut a piece of glass 1/8” smaller than the frame on all four sides. This will allow the glass to sit inside the groove but leave room for the wood to expand and contract with changing weather conditions. Take your measurement at a number of locations along the frame to determine if you need to adjust for minor variations. Never transport or store your glass horizontally. Glass will be less likely to break if kept upright.

Prepare the Frame

Apply a narrow (1/8”) bead of caulk on all four sides of the groove, making a practice line on a piece of paper towel before you begin. If you are not using caulk from a tube, roll ropes of caulk the length of each side of your window and press in place with your putty knife or finger.

Put the Glass in Place

Once you have affixed caulk on all four sides of the window frame, carefully place the glass on the frame beginning with one of the lower corners, seating it carefully. Press the glass gently around the edges to make a firm bond.

With your thumb or a screwdriver, press glazing push points into the wood every eight inches around the frame starting an inch from each of the four corners. Be careful not to accidentally chip the glass as you install the push points.

Seal The Window

Run a larger bead (1/4”) of caulk around all four sides of the glass, pressing gently with a putty knife to make sure it makes good contact with both the glass and the wood frame. Slant the putty knife and apply long strokes to create a beveled finish and make a strong seal.

Scrape off the excess caulk and clean any residue from the glass with paint remover. After the caulk has been left to cure according to manufacturer’s instructions, prime and paint. In order to create a finished look, scrape any uneven paint with a single edge razor.

Special Instructions for Aluminum Windows

Replacing the glass in aluminum windows usually requires fewer steps than outlined above. You don’t need to lubricate with linseed oil before applying caulk, and instead of being held in place with glazing points that have to be removed and replaced, the glass in aluminum windows is usually affixed with spring clips or gaskets that can be reused.

Cleanup and Safety

Always use good judgment when working with glass and razors. When discarding broken glass, use a heavy-duty bag. To ensure safe disposal, tape the bag shut before you place it in your trash receptacle. Never use a double-edge razor to scrape paint, and single edge razors should be used with handle tools. Always remember to wear goggles when removing glass shards.

When replacing windows, measure carefully, read and follow manufacturer’s instructions on curing times, and always prime and paint after the glazing compound has had a chance to cure completely.