the disabled and structural stability (including earthquakes). The International Building Code applies to all structures in areas where it is adopted, except for one and two family dwellings (see International Residential Code). Parts of the code reference other codes including the International Plumbing Code, the International Mechanical Code, the National Electric Code, and various National Fire Protection Association standards. Therefore, if a municipality adopts the International Building Code, it also adopts those parts of other codes referenced by the IBC. Often, the plumbing, mechanical, and electric codes are adopted along with the building code. The code book itself (2000 edition) totals over 700 pages and chapters include: Building occupancy classifications Building heights and areas Interior finishes Foundation, wall, and roof construction Fire protection systems (sprinkler system requirements and design) Materials used in construction Elevators and escalators Already existing structures Means of egress (see below) Means of egress The phrase "means of egress" refers to the ability to exit the structure, primarily in the event of an emergency, such as a fire. Specifically, a means of egress is broken into three parts: the path of travel to an exit, the exit itself, and the exit discharge (the path to a safe area outside). The code also addresses the number of exits required for a structure based on its intended occupancy use and the number of people who could be in the place at one time as well as their relative locations. It also deals with special needs, such as hospitals, nursing homes, and prisons where evacuating people may have special requirements. In some instances, requirements are made based on possible hazards (such as in industries) where flammable or toxic chemicals will be in use. Accessibility "Accessibility" refers to the accommodation of physically challenged people in structures. This includes maneuvering from public transportation, building entry, parking spaces, elevators, and restrooms. This term replaces the term "handicapped" (handicapped parking, handicapped restroom) which is generally found to be derogatory. Accessibility can also include home automation type systems. Existing structures Building code requirements generally apply to the construction of new buildings and alterations or additions to existing buildings, changes in the use of buildings, and the demolition of buildings or portions of buildings at the ends of their useful or economic lives. As such, building codes obtain their effect from the voluntary decisions of property owners to erect, alter, add to, or demolish a building