Section 602.2/Types of Construction
IBC 602.2 through 602.5 define the five types of construction (Types I through V) based on materials and fire-resistance ratings of structural elements.
Buildings are classified into five construction types. Type I and Type II use noncombustible materials; Types IA and IIA require fire-resistance ratings on structural elements while Types IB and IIB allow reduced or zero ratings. Type III has noncombustible exterior walls but permits combustible interior elements. Type IV is heavy timber construction. Type V permits combustible construction throughout. The fire-resistance ratings for each type are specified in Table 601.
Why this section exists
The construction type classification determines the fundamental fire performance of the building structure. It cascades into almost every other design decision: allowable height and area (Chapter 5), fire- resistance requirements (Table 601), interior finish requirements, and whether certain trade-offs are available. Getting the construction type wrong invalidates the entire code analysis.
What plan reviewers look for
Plan reviewers verify that the stated construction type is consistent with the structural materials shown on the drawings. They check that the fire-resistance ratings in the wall sections, floor assemblies, and structural details match the requirements of Table 601 for the stated type. They also verify that the construction type supports the claimed height and area in the code analysis.
Common violations
Related IBC requirements
Table 601 specifies the required fire-resistance ratings for each construction type. Chapter 5 (Sections 503 through 510) establishes allowable height and area based on occupancy and construction type. Table 602 covers exterior wall fire-resistance based on fire separation distance.