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Frame construction is ISO Class 1.  ISO Class 1 encompasses IBC Type VA and IBC Type VB.  Regardless of whether the IBC classification is A (protected) or B (unprotected) the ISO Class is 1. Frame buildings are buildings with exterior walls, floors, and roofs with combustible construction — or buildings with exterior walls of noncombustible or slow-burning construction with combustible floors and roofs.  Frame buildings generally have roof, floor, and supports of combustible material, usually wood, and combustible interior walls. Two variations on frame construction don't change the construction class:  Masonry veneer (brick veneer)- Masonry veneer is thin layers of brick, stone, or stucco, used for appearance purposes rather than structural support. Metal clad - A building with a metal exterior wall may not look like frame construction, but when the metal skin is attached to wood studs and joists, ISO classifies the building as frame.   Other conditions that lead to classification as frame construction include:  Metal walls or floors sheathed with combustible materials Metal floors or roofs with combustible insulation or ceiling material attached to the underside or within 18 inches (45.7 cm) of horizontal supports Composite assemblies of noncombustible materials with combustible materials easy to erect and alter economical versatile performs well in Earthquake areas – can move fire can spread rapidly highly damageable may become unstable in a fire  may include enclosed spaces where fire can spread undetected
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