Abstract: A steel window structure for modern day double paned insulating glass simulating the narrow, elegant sight lines of older steel window structures which secured monolithic, non-insulating glass windows is described. The window securing structure is made deeper and narrower than is currently available in steel windows. This structure now accommodates a single pane of glass of up to 1" thick glass, or up to 1" thick double paned insulating glass. Additionally the new structure inherently provides a thermal break between exterior and interior metal components, the convenient use of two color factory applied finishes for the steel members, and superior air and water resistance over current structures, while at the same time providing the narrow sight lines previously seen only in the older, non-insulating glass steel window structures. Moldings connected to the exterior steel structure provides a "putty slope" shadow effect to complete the simulation of the older steel window structure.

Abstract: A window structure for use as a new or a replacement window in a wall opening is provided. This window structure includes, a tubular interior frame unit, a tubular exterior frame unit, insulating glass units, and seal means between the frame units. The tubular exterior frame unit overlaps and has substantially the same projected member width as the tubular interior frame unit for providing a slim appearance to the metal parts and for providing a large appearance to the glass parts. The tubular interior frame unit has a first tubular frame portion, and has a second flange frame portion, and has a third heat-barrier frame portion therebetween, for minimizing heat loss. Each insulating glass unit has two spaced glass sheets with a sealed air space therebetween. The seal means has a continuous primary seal member mounted on the first tubular frame portion for engaging a tubular exterior operable outswing casement frame of the tubular exterior frame unit.