Building codes are the rules that govern how buildings are constructed. They set minimum standards for structural strength, fire safety, egress, accessibility, energy efficiency, and sanitation. The goal is simple: buildings should not collapse, catch fire easily, or trap people inside.

Codes are adopted by local governments, usually based on model codes developed by national or international organizations. The International Building Code is widely used in the United States. Each jurisdiction can amend it to suit local conditions — seismic zones, hurricane regions, snow loads.

Complying with the code is not optional. Plans are reviewed by building officials before construction, and inspections occur during the work. A certificate of occupancy is issued only when the building meets the code.

Codes evolve. After major fires, earthquakes, and hurricanes, they typically get stricter. That is why older buildings often do not meet current standards, and why renovations frequently trigger upgrades.