I've lived in two 50's houses where the windows were replaced with double pane. Both window replacements were mediocre at best. Replacement windows are a bit

I've lived in two 50's houses where the windows were replaced with double pane. Both window replacements were mediocre at best. Replacement windows are a bit smaller than the original windows so there is a gap between the house framing and the window frame. In neither house did the installer do an adequate job of sealing that gap. On one window, I could even see daylight through the gap. I had to remove the inside trim and spray in foam.