Building code

A building code is the body of minimum construction standards a jurisdiction has adopted into law. Almost no jurisdiction writes its own from scratch. Instead a model code is adopted, then amended locally.

The model codes

The International Code Council publishes the family in general use across the United States: the International Building Code for commercial and multifamily work, the International Residential Code for one and two family dwellings, and companion codes for mechanical, plumbing, fuel gas, energy, and existing buildings. The National Electrical Code covers electrical work.

Adoption and amendment

A model code has no legal force until a state or local government adopts it. Adoption lags publication, often by years, and jurisdictions amend as they adopt. Florida and California both maintain heavily amended statewide codes built on the model codes.

The consequence is that "the code says" is an incomplete sentence. What governs is the specific edition your jurisdiction adopted, with its local amendments, and that combination is what the reviewer is applying.

Which edition governs your project

Normally the one in effect when the application is filed, not when the design started or when construction happens. Projects filed just before a new edition takes effect are usually reviewed under the old one, which is why adoption dates can be worth a few weeks of schedule.

Code versus zoning

The building code governs how a building is constructed. Zoning governs what may be built and where it may sit. They are separate bodies of rules, reviewed by different people, and a design can satisfy one and fail the other.