Now that you’ve finally learned the (model) code, it’s all different!At long last, after three years of proposed code changes, code hearings, floor votes, public comment period and final action hearings, a new International Residential Code (IRC) is developed and published. You’ve purchased it from the International Code Council and read through it in anticipation of a green-home building project.Now keep in mind, the IRC is just a guide, a model building code, and does not have the force of law until adopted. Normally during this adoption process the jurisdiction will add or subtract code requirements or modify the provisions that better suit that region’s interest. These modifications are usually known as local amendments.The adoption and enforcement at the local level varies across the nation according to each state’s organization and constitution; and whether the state is a “Dillon-rule” or a “home-rule” state. Generally, a Dillon-rule state is said to have complete authority over municipal government except as limited by the state or federal constitution. Because of this complete legislative control, a city or county government’s power is limited and only extends to the following: (1) rule of law (2) implied or incidental and (3) absolutely indispensable.Home rule can defined as letting the city or county enforce the state law. It transfers the authority from the state to the locality. About 40 states are home-rule, and about 10 are Dillon-rule. A Dillon-rule state will, generally (there are exceptions to every rule) have a statewide building code, and a home-rule state will have variations of state and local building codes. So check to determine what building code is enforced in your community.The State of Virginia, for example, is a Dillon-rule state and therefore has a statewide building code called the Uniform Statewide Building Code (USBC). The adoption process for states, cities, or counties, irrespective of the state’s status, usually includes formal steps such as public notification, hearings, and, finally, acceptance. While the adoption process is pretty much the same nationwide, the changes themselves vary according to the locality or region.As much as the IRC is written to be a national standard, unique geographic or political influences tend to have an effect on the code. For instance, New Mexico and areas of Arizona have significant amendments to regulate earthen construction; adobe and rammed earth. Virginia has stair geometry with steeper inclines that the IRC permits. Almost 100 cities have green-building programs adopted that modify the code. There may be more restrictive requirements such as mandatory fire suppression systems for all homes, as in Scottsdale, Arizona. There may be a reduced requirement or even importation one or more of the appendices into the body of the code.Generally, the administrative provisions are changed to match the state law for permits, code violations, penalties, and such. It is important to have the model code itself, since these amendments are limited to the changes and not the bulk of the code itself.Be sure to check with your locality before designing a green home, getting a permit or calling for inspections. Things could be different than you’d expect! For example, there may be materials (like straw bale or adobe) that are permitted at the locality. There may be height or size limits on other materials, such as insulated concrete forms.