Class S buildings are characterized by incombustible construction and prefabricated structural members. They are not fire-resistant buildings. The exterior walls may be steel studs or an open-steel-skeleton frame with exterior coverings of prefabricated panels or sheet siding. Upper floors and roof are supported on steel joists or beams. Ground floors are typically concrete slabs.
Included in this class are Uniform and Standard Building Code construction, Type IV (noncombustible), Basic Code Type V and ISO Class 3 buildings. This class is also referred to as Noncombustible and can be One-hour Type II construction.
Note: For metal slant frame and walls, use Class W.