Type I and II Construction have building elements that are noncombustible.
Type III Construction has exterior walls of noncombustible materials and the interior building elements are of any material permitted.
Type IV Construction has exterior walls are of noncombustible materials and the interior building elements are of solid or laminated wood without concealed spaces.
Type V Construction has building elements that are of any materials permitted.
The information provided above is for general use only and the final determination for the Construction Classification shall be made by the registered design professional, for the determination between an A or B classification an applicant must determine the fire resistance rating of the building elements.
Additional information is available in the International Building Code specifically Chapter 6 Types of Construction.