How to Install Replacement Windows in Old Window Nailing Flanges

Most older homes have either aluminum- or wood-framed windows.

Most older homes have either aluminum- or wood-framed windows. Replacement options range from full window and frame replacement to replacing just the glass panes. According to Jake Arnesen a Seattle-based general contractor, replacing the glass panes is less expensive but requires some skill and patience. "Both wood and aluminum frames hold the glass pane in the same way", says Arnesen. "There is a solid protrusion on the interior of the frame and a stop on the outside of the frame. The glass panes are set in using either glazing putty or glazing tape, then stops are installed over the pane to lock it in." To avoid breaking the glass, Arnesen suggests using care when removing and installing the panes.

Things You'll Need

• Finish pry bar
• Small pry bars or painters 5 in1 tool
• Chisel or putty knife
• Fein Multimaster putty scraper attachment
• Vacuum window pucks
• Latex gripper gloves
• Glazing tape
• 1/8-inch shims
• Caulking gun (wood windows)
• Latex caulking
• Glass cleaner

Instructions

Remove Old Window

1. Using a finish pry bar, carefully remove the stop material. On wood-framed windows these stops materials can be old and brittle. Utilizing two pry bars helps with this process.

2. Use a putty knife to loosen any putty that my be adhered to the stop. This is most common in wood-framed windows. Aluminum frames have either a metal or vinyl stop.

3. Inspect the window pane for any chips or cracks once the stops are removed.

4. Separate the glazing putty/tape from the window. Arnesen recommends the Fein Multimaster putty scraper attachment for this process. Work your way all the way around the pane, making sure to separate the full width of the glazing putty/tape. Older wood windows may also have glazing putty on the thin side of the window, which must be removed.

5. Using two vacuum pucks, slowly pull the pane out.

6. Clean the frame by removing the glazing putty/tape with a putty knife. Use a sharp chisel on wood frames, working slowly to avoid gouging the wood. Clean the frame thoroughly, making sure it is smooth and free of defects.

Install New Window

1. Install glazing tape, preferably size 1/16-inch. Press it into place as you go, making sure to keep an even reveal on the frame until all sides are done.

2. Remove the vinyl protecting on the pane side of the adhesive. Place two 1/8-inch shims at the bottom of the frame. Spraying glass cleaner on the glazing tape to retard the adhesive allows time to adjust the pane.

3. Use the vacuum pucks and gloves to lift the new glass pane into place setting it on the 1/8-inch shims. Proper pane installation should have a 1/8-inch gap between the glass and the frame on the perimeter. Adjust as necessary and press firmly into the glazing tape. If you have sprayed the glass cleaner on the tape, you may have to hold it in place for a minute or so, when the adhesive becomes active again. The pane is now set.

Install Stops

1. Push the stops into place, top first, sides second and bottom third if you are working on aluminum window frames. On wood window frames, use good quality latex caulking to fill the gap on the perimeter of the pane, leaving a little out for the wood stop. Set the stop in the caulking and nail it into the frame. Be careful with the nail direction to avoid breaking the glass.

2. Clean any excess caulking off immediately with a rag or wait a day and scrape off the excess with a razor blade.

3. Clean the window.

Tips & Warnings

• Vinyl stops on the bottom of the frames tend to be brittle due to weathering. Use caution when removing.

• Large panes may require two or even three people to remove and set.

• Glass will flex, but flexing too much will cause it to break. Older glass is usually more brittle and can break into dangerous shards.

References

• Jake Arnesen; General Contractor; Seattle, Washington