definition
strict definition
metal
A load-bearing frame composed of pure or alloyed metallic structural members.
A metal frame is a load-bearing skeletal structure composed of solid metallic members such as beams, plates, and connecting elements.
The metallic members form the supporting skeleton. Steel is one material within this family.
A metal facade is an exterior covering and can exist over a framework of another material. The presence of metal in the facade alone does not establish a metal structural frame.