I have those old steel basement hopper windows (see post1 and post2 for example pics). Rather than add storm windows to them, an option to explore is to replace them. There's plenty of questions about this and some people caution that the steel frame may support stuff from above (acts like a header) with little explanation of why. Well, I'd like to know why. So, I'm asking WHAT makes a steel window frame structural (or not)? Is it the size, proximity to the sill plate, thickness of the steel, etc.?

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    A Picture of your window frame will help, but unless it is very heavy steel, it probably is not structural/load bearing. Most window frames are made to fit into a hole in the wall. Having a window in or not is usually more to keep the bugs and cold air out, than to hold up the house. Glass does not like pressure/weight on it.
    – crip659
    Jul 20, 2023 at 23:11
  • To be clear, I'm not asking about my particular frame. I'm looking for information about how people tell if a frame is structural or not. Hope that clears things up. Jul 20, 2023 at 23:21
  • Just to confirm, you are asking about the window frame that the glass sits in. If the hole that a window frame fits in is made from heavy(inch plus) steel or I beams, that is probably structural. The steel/metal frames that some windows are made with are not structural(except for the window).
    – crip659
    Jul 20, 2023 at 23:37
  • I'm asking about the window frame, not the sash that holds the glass. When you say inch thick steel, are you referring to width, or thickness (and it sounds like an answer). Jul 21, 2023 at 13:18

1 Answer 1


I know of no type of window frame of any material that is structural, with one exception. That being structural steel and glass panels when used in building construction As seen here:enter image description here

Or here:enter image description here

Since your basement window is not like these, I think you are safe to replace them. The concrete wall with a lintel over each window supports the load.

  • Interesting. I'm curious, could you elaborate why metal frames aren't structural? For example, is it because they're aren't beefy enough, or because it's a code violation, or maybe "it simply was never done that way"? Jul 21, 2023 at 13:21
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    I did not say METAL frames are not structural. I stated that Window frame material is not structural. As it is the Frame for the glass and not intended as support for another part of the structure. Having a window frame as a structural component in a residential dwelling would be grossly unusual. This is common sense and should not need to be stated.
    – RMDman
    Jul 21, 2023 at 13:28
  • Sorry, but you took me too literal. My post is about metal WINDOW frames. Excuse me if I left out the word "window" in my comment. Jul 21, 2023 at 13:34
  • Window frames are not structural because that would make them unnecessarily expensive and hard to service. In wood, they are framed around. In concrete, a plate may be placed above them to bridge the opening and transfer force. Metal or not.
    – keshlam
    Aug 20, 2023 at 3:16

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