steel
A roof-supporting framework made of steel beams, poles, sheets, or other steel structural elements.
A steel roof frame is an underlying support framework for a roof built out of steel beams, poles, sheets, or other elements constructed from steel.
Steel forms the underlying support rather than merely a surface finish. Beams, poles, and sheets are examples of possible elements.
The outer covering can be another material. A steel roof frame is identified from its supporting elements rather than from the appearance of the roof surface.
