In some countries the building codes are National Codes and apply across the country. In other countries the laws are adopted at a municipal or subnational entities level. In these cases a model building code system is usually used. In other cases jurisdictions may adopt national or model codes from other jurisdiction.
Building codes generally include:
- Structural safety: buildings should be strong enough to resist internally and externally applied forces without collapsing;
- Fire safety: includes requirements to prevent the fire spread to/from neighbours, provide warning of occupants, and safe exiting of building, limitation on fire spread, and provisions for fire suppression/fire fighting;
- Health requirements: adequate washrooms, adequate air circulation, plumbing materials.
Some building codes sometimes include requirements for:
- Accessibility: requirements to ensure that a building is accessible for persons in wheelchairs or having other disabilities.
Building codes generally do not include:
- Aesthetics: Any regulation of the aesthetics of buildings are usually included in zoning by-laws;
- Traffic convenience: Limitations on traffic flow are usually either in zoning or other municipal by-laws;
- Building Use: the safe use of a building is generally in the Fire Code; or
- Required upgrades for existing building: unless the building is being renovated the building code usually does not apply.
Building codes include:
- specifications on components;
- allowable installation methodologies;
- minimum and maximum room and exit sizes and location;
- qualification of individuals or corporations doing the work.
These requirements are usually a combination of prescriptive requirements that spell out exactly how something is to be done, and performance requirements which just outline what the required level of performance is and leave it up to the designer how this is achieved. Historically they are very reactive in that when a problem occurs the building codes change to ensure that the problem never happens again. In recent years there has been a move amongst most of the building codes to move to more performance requirements and less prescriptive requirements.
Building codes are generally long complex interrelated sets of rules. They generally include reference to hundreds of other codes, standards and guidelines that specify the details of the component or system design, specify testing requirements for components, or outline good engineering practice. Building codes are generally intended to be applied by architects and engineers. There is often other codes or sections of the building code that have more prescriptive requirements that apply to housing (one and two family dwellings).
Building codes have a long history. What is generally accepted as the first building code was in the Code of Hammurabi which specified that if you build a building and it falls and kills the owners son, the builders son would be put to death.