International Building Code 3407.1
Historic buildings. The provisions of this code relating
to the construction, repair, alteration, addition, restoration and
movement of structures, and change of occupancy shall not be
mandatory for historic buildings where such buildings are
judged by the building official to not constitute a distinct life
safety hazard.
International Building Code 3407.2
Flood hazard areas. Within flood hazard areas established
in accordance with Section 1612.3, where the work proposed
constitutes substantial improvement as defined in
Section 1612.2, the building shall be brought into conformance
with Section 1612.
Exception: Historic buildings that are:
1. Listed or preliminarily determined to be eligible for
listing in the National Register of Historic Places; or
2. Determined by the Secretary of the U.S. Department
of Interior as contributing to the historical significance
of a registered historic district or a district preliminarily
determined to qualify as an historic district;
or
3. Designated as historic under a state or local historic
preservation program that is approved by the Department
of Interior.