International Building Code (IBC)

The IBC is the flagship of the I-Code family, a coordinated set of model codes covering buildings, fire, plumbing, mechanical systems, energy and more, revised on a three-year cycle. As a model document it has no force anywhere by itself; each state or local jurisdiction adopts a specific edition, attaches its own amendments, and thereby turns the model into law for its territory. The code regulates by occupancy and risk — use classifications, construction types, heights and areas, egress, fire protection, structural criteria — and does much of its detailed work by referencing standards, pulling large parts of the standards world into law by citation.

The practical consequence of the adoption model is fragmentation with a common skeleton: neighbouring jurisdictions can be on different editions with different amendments, and "IBC-compliant" is not a property a design can have in the abstract. The first question of any US project is which edition, as amended by whom — and the answer decides real requirements, because the three-year cycles are not cosmetic.