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Old Metal Windows

William Kibbel III, The Home Inspector

Our home has single-paned metal casement windows, probably from the early '40s. Some don't open and several don't close tightly. I'm pretty sure we're loosing a lot of heat because of the single panes. Can anything be done to repair them or would you recommend replacement? Keep in mind that we probably couldn't afford good replacement windows unless money falls out of the sky.

I remember the steel casements in a mid 1930s addition on my first home. At least most of the sashes that still opened were the important ones (I decided that the sashes that didn't work weren't important). I had always intended to replace the steel windows so they received no attention. All the other projects in that home prevented me from getting around to replacing them.

Clear Away the Buildup

The first step in restoring casement windows would be to completely remove and inspect the hardware. If the lock mechanisms are broken or the operating gears are stripped, replacement parts may be needed. This might be time consuming, but finding them is certainly easier now with Internet searching and message boards. If these working parts are intact, then safe removal of old paint and thorough cleaning could bring them back up to their task.

A buildup of dirt, debris, and layers of paint where the sash meets the frame is the most common culprit of casements not opening, closing, or sealing properly. The protruding hinges may also be obstructed as well. I wouldn't hesitate in safely stripping, scraping, and sanding them to the bare metal. This would also expose any corrosion, cracks, or other failures that may be hidden by decades of re-paintings and which will need to be repaired at this stage. If there is deep corrosion or other major damage like frames that have been butchered for air conditioners, someone experienced with welding will need to be brought in to replace and repair the steel as needed.

Back into Shape

Sometimes window sashes are bent and deformed, usually from folks trying to force or pry open stuck windows or intensely coercing them to close on debris or thick paint. Bending them back into shape to fit tightly into the frame is a very tricky and tedious task. Take your time on this step. You'll want the tightest fit possible without having to replace broken glass. If perfectly aligned when closing, all sash edges should meet the frame surface simultaneously. There may also be some adjustments and lubrication of moving parts that can help get the sashes moving smoothly.

Preserve and Maintain

The next steps are the same as if working with any type of windows. All glazing putty that is missing or cracked should be replaced. The window sashes and frames need to be primed and painted (with special paints for steel). The operating hardware must be cleaned and lubricated every few years.


Many types of weather-stripping are too thick to be used on steel casements without distorting the frame or sash or stressing the hardware. The most successful in my opinion is simply silicone caulk. A very thin bead of the sealant is applied continuously around the painted and clean frame. A bond breaker tape (the caulk doesn't stick to polyethylene) is applied around the perimeter of the sash and the window is closed. After the caulk sets up, the bond breaker tape is removed and the caulk has created a custom-fitted gasket, keeping out drafts and rain.

Hopefully your windows can be restored to satisfactory working condition. Then you can open them quickly to reach out and grab some cash if it ever does fall out of the sky.

About the Author
William Kibbel III is a home inspector and restoration consultant specializing in historic residential and commercial buildings. He is vice president of Tri-County Inspection Company, serving Southeastern Pennsylvania and Central New Jersey.

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