The International Residential Code (IRC) is developed by the International Code Council as a single, comprehensive code for residential construction including single-family homes, duplexes, townhouses, and small multi-family buildings up to 3-4 stories. The IRC adopts provisions from the IBC but customizes them for residential applications where occupancies are smaller and fire risks are different. The code applies to detached single-family dwellings, duplexes, townhouses, and condominiums with up to 3 stories above grade plus basement. Buildings exceeding these limits must comply with the IBC. The IRC covers all building systems including foundations, framing, roof construction, fire and smoke protection, interior finishes, plumbing, mechanical systems, electrical systems, energy conservation, and exterior walls. The code permits alternative materials and methods when they achieve equivalent performance to code-compliant methods. The code allows reasonable interpretations and exceptions for existing buildings and alterations. Owner-builders are often permitted to build their own homes without licensed professional design under IRC provisions, though structural design calculations may be required for complex buildings. The IRC addresses common construction practices in residential building including conventional wood framing, standard foundation types, and typical mechanical and electrical installations. The code is performance-based in many areas, permitting alternative approaches if the desired performance level is achieved.