International Residential Code

The prescriptive code for one- and two-family dwellings and townhouses up to three storeys, covering structure, fire safety, energy, plumbing, mechanical and electrical in one document. Prescriptive is the word that matters: it gives spans, spacings and thicknesses that may be built without an engineer's calculation, for buildings inside its limits.

A building outside those limits does not fail the code, it leaves the code's scope and needs a design. Where its provisions and the IBC's overlap, which applies is a question about the building's occupancy and size rather than about the documents.

Its energy provisions are the part most often superseded locally: many jurisdictions adopt the IRC for structure and a separate energy code for everything thermal, so two documents govern one wall. It assumes a building of ordinary risk on ordinary ground.

High wind, seismic design categories beyond its tables, expansive soils and flood zones all push a dwelling out of its prescriptive path and into engineered design.

Obtained from International Code Council. What ICC publishes

Published: 2024, 2021, 2018, 2015. A new edition every three years.

Cited here as 2024.