Building Classifications: Construction Types

 Based on how the building is constructed.  Relates to:  Materials used  Combustibility  Fire-resistance

 Types IA and IB  Types IIA and IIB  Types IIIA and IIIB  Type IV  Types VA and VB

 Types IA and IB  Noncombustible and fire-resistive  IA has a higher fire-resistance  Only noncombustible materials allowed  IBC does not determine combustibility  Done through the American Society for Testing and Materials (ASTM)

 Types IIA and IIB  Also noncombustible  Little or no fire-resistance  IIA has minimum of 1-hour fire-resistance  IIB has no requirement for fire-resistance unless required by other sections of the code

 Types IIIA and IIIB  Combustible  Permits wood framing  Little to no fire-resistance  IIIA requires 1-hour fire-resistance throughout with exterior bearing walls 2-hour  IIIB only requires 2-hour fire-resistance for exterior bearing walls

 Type IV  Combustible  Heavy timber construction only  Columns at least 8” thick  Floor and roof framing at least 6” thick  Floor and roof decks 3-4” thick (built up)  Exterior walls noncombustible construction

 Types VA and VB  Combustible  Slightly less fire-resistance than Type III  VA exterior bearing wall fire-resistance is 1-hour  VB has no fire-resistance rating

 A building or portion thereof shall not be required to conform to the details of a type of construction higher than that type, which meets the minimum requirements based on occupancy even though certain features of such a building actually conform to a higher type of construction.

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