Class C buildings are characterized by masonry or reinforced concrete (including tilt-up) construction. The walls may be loadbearing, i.e., supporting roof and upper floor loads, or nonbearing with concrete, steel or wood columns, bents or arches supporting the load. Upper floors and roofs are supported by wood or steel joists or trusses. Ground floors may be concrete slabs. Upper floors may be of concrete plank, steel deck or wood. Bearing walls are frequently strengthened by concrete bond beams and pilasters. Class C buildings are not fire-resistant structures.
Included in this class are Uniform and Basic Building Code, Type III (noncombustible wall), Standard Code Type V and ISO Classes 2 and 4, and those ISO Class 5 and 6 buildings that have load-bearing walls without interior framing and of low-rise design (3 stories or less). This class is also referred to as Masonry or Unprotected Noncombustible, Joisted or Unprotected Masonry, or Ordinary or Unprotected One-hour, and includes certain Two-hour or heavy timber construction.