Which of the following is NOT a characteristic of Type III Ordinary construction?

Type III Ordinary construction is characterized primarily by its mix of combustible and noncombustible materials. This type of construction typically features exterior walls made of noncombustible materials, while allowing for interior structural members, such as wooden beams and columns. Therefore, it's accurate to say that while some structural elements may use combustibles like wood, not all structural members are made of metal.

Since Type III construction permits a variety of materials, particularly inside the structure, having all structural members made of metal would contradict the defining traits of this construction type. Hence, the accurate understanding of Type III Ordinary construction makes it clear that option stating "all structural members are of metal" is indeed not characteristic of this construction type.