Building codes are the law. Building codes are an area's official rules on building safety. Anyone tackling a construction project (including a homeowner doing DIY work) is legally required to follow these rules. For all but the most minor cosmetic building projects, city inspectors will check to make sure that building codes were followed. International building codes keep things uniform. Most cities and municipalities choose to adopt a set of universal building codes for residential construction that are developed and updated by the International Code Council (ICC). Collectively, these are referred to as the International Residential Code (IRC). Municipalities can they layer more specific rules on top of the IRC or otherwise amend certain rules.