The challenge of replacing metal windows

If your home was built before 1985, you may have metal windows, either aluminum or steel. Most of the glass in these windows had a warranty of up to 20 years, which by now has expired and the glass may have failed, in which case, you are probably tired of the condensation. The painted metal frames are faded, the weather-stripping is matted down and totally ineffective; they leak air and, perhaps, water. It's time for new windows.

However, it may not be as easy as buying replacement windows you find advertised on TV, radio, and in the papers. Most of those windows are "pocket" replacement windows, designed with 3 ¼-inch jambs to fit neatly into the space occupied by the sash of a wood window -- not metal. The total depth of a wood window is 4 ⁹/₁₆ inches. Aluminum windows are only 2 inches to 2 ¾ inches.

How to replace metal windows with vinyl or wood windows

Because your metal windows are so much thinner, they do not fill out the entire depth of the window opening. The remainder has been filled in with wood or drywall, so replacing your metal windows is going to be more difficult than swapping out wood for wood or vinyl windows -- but not impossible. There are two ways:

1. The drywall or wood return might have to be removed to fit the new, deeper window.
2. A thinner, new construction window, rather than a replacement window, can be used.

The second option requires removing the nailing fin that projects from the metal frame. It's the fin that makes removal of the window difficult. Usually, in order to not disturb the exterior siding, the glass is removed, and then the frames are cut, collapsed and pulled out of the opening.

Sealing the new window against water intrusion can be challenging, too, but not insurmountable. Properly flashed and sealed, your new windows can effectively shed water away from the wall.

While all this work can be more expensive than just replacing a wooden sash with a pocket window, proper removal of existing windows, installation, and finishing can yield great results. Your old, pitted, hard-to-open, leaking metal windows can be changed to new, clean energy-efficient vinyl or wood windows.