Most municipalities and local code bodies do not write code – they adopt model codes 
prepared by various code bodies.
Historically, model codes were prepared by code bodies such as Building Officials Code Administrators International, Inc. (BOCA) – the National Building Code (NBC); Southern Building Code Congress International (SBCCI) – the Southern Building Code (SBC); and the International Conference of Building Officials (ICBO) – the Uniform Building Code (UBC).
These various model building codes were adopted regionally by local authorities. With multiple code bodies, it was difficult to keep abreast of proposed changes by those not directly involved in the code process – e.g. architects, manufacturers, and contractors.
In 1999, BOCA, SBCCI, and ICBO began to work together to prepare a unified code under the auspices of the ICC.
The first set of I Codes® were published in 2000 and included the International Residential Code (IRC) and the International Building Code (IBC). The IRC applies to one and two-family dwellings while the IBC applies to commercial buildings and multi-family residential construction. The I-Codes have since been adopted by states and municipalities throughout the country. They are published every three years – the most recent publication was in 2015.
The I-Codes are model codes. Local code authorities generally do not have the human resources to write their own code so they adopt code using the model codes as the basis for their requirements. They may choose to adopt as is or make changes as they deem appropriate. Your local jurisdiction may also be using an older of the I-Codes.
The I-Codes provide minimum safeguards for people at home, at school, and in the workplace. Based on your application a minimum standard may not be considered sufficient. The local authority having jurisdiction (AHJ) may reject your installation if – in their opinion – your installation is unsafe.
Always check with your local AHJ prior to proceeding with an installation.
Anyone can submit a code change but be prepared for a multi-year process that will involve attending code hearings to justify the requested change. Code books are available for purchase but you can view individual sections of the IBC and IRC on-line for free at www.iccsafe.org.