What is Building Code?
The Building Code is an instrument providing guidelines for regulating the building construction activities across the country. Building codes are generally intended to be applied by architects, engineers, interior designers, constructors, and regulators but are also used for various purposes by safety inspectors, real estate developers, and others. Codes that regulate the design and construction of structures were adopted into law.
Why Building Code?
A building code (also building control or building regulations) is a set of rules that specify the standards for constructed objects such as buildings and non-building structures. Buildings must conform to the code to obtain planning permission, usually from a local council. The primary purpose of building codes is to protect public health, safety, and general welfare as they relate to the construction and occupancy of buildings and structures. The building code becomes the law of a particular jurisdiction when formally enacted by the appropriate governmental or private authority.
History of Building Code
King Hammurabi enacted the first known written building code in Babylon in 1758 B.C. written in stone. The code doesn’t have a guideline on how to work and what steps to use. Instead, it states that “If a builder has built a house for a man and his work is not strong, and if the house he has built falls in and kills the householder, that builder shall be slain.”
After the great fires in London in 1666 and Chicago in 1871, building codes started addressing the risks one building posed to adjacent buildings and the public. Denser development in cities, and hazards associated with proximity and taller buildings, led to regulations for the construction of common walls between buildings and outlawing dangerous practices like wooden chimneys. Problems in existing buildings led to codes for light and ventilation, fire escapes, toilets and sanitary drains, and stairs and railings.
In 1905, the US organization, the National Board of Fire, created the first National Code to minimize risk. By 1940, the United States had three regional code organizations, each with its own code. These three organizations and their codes were consolidated into the International Code Council (ICC), and the first set of “I-codes” was published in 2000. These codes include the International Building Code (IBC), the International Residential Code (IRC), the International Energy Conservation Code (IECC), as well as mechanical, plumbing, fire and other codes.
Types & Classification of the current building structure
There are instances when some local jurisdictions choose to develop their own building codes. A long time ago, all major cities in the United States had their own building codes. However, due to the ever-increasing complexity and cost of developing building regulations, virtually all municipalities in the country have chosen to adopt model codes instead. For example, in 2008, New York City abandoned its proprietary 1968 New York City Building Code in favor of a customized version of the International Building Code. The City of Chicago remains the only municipality in America that continues to use a building code the city developed on its own as part of the Municipal Code of Chicago.
In Europe, the Eurocode is a pan-European building code that has superseded the older national building codes. Each country now has National Annexes to localise the contents of the Eurocode.
Similarly, in India, each municipality and urban development authority has its own building code, which is mandatory for all construction within their jurisdiction. All these local building codes are variants of a National Building Code, which serves as model codes providing guidelines for regulating building construction activity.
Under the building code, constructed building or newly built structures can be classified on the following basis-
- Use and Occupancy
- Types of Construction
Use and Occupancy
The IBC has ten main occupancy groups as well as multiple subgroups. The occupancy group or subgroup defines the specific use of the building. Subgroups are numbered based on the perceived risk for the building occupants. The lower the subgroup number, the higher the perceived threat.
In many cases, a building has space that may be classified under more than one occupancy group. These multi-use buildings are identified as a Mixed occupancy type. However, if a building space can be considered as either an Accessory occupancy or an Incidental Use area, it may become part of the leading occupancy group.
Occupancy type determines the vertical live loading requirements for the building structure. For higher-risk buildings such as a fire station, school, or theatre, lateral loads (e.g. wind and seismic) and snow will require increases to the loading requirements.
Groups A-1, A-2, A-3, A-4, & A-5
Gatherings – civic/religious/social/recreational
Office/Professional or Service Transactions
K-12 Schools (some Daycare)
Groups F-1 & F-2
Groups H-1, H-2, H-3, H-4, & H-5
Groups I-1, I-2, I-3, & I-4
Display & Sale of Merchandise
Groups R-1, R-2, R-3, & R-4
Groups S-1 & S-2
Non or Low-Hazardous Storage (including parking garages)
Utility & Miscellaneous
Construction Type identifies the type of materials utilised for constructing a building and classifies the level of combustibility and fire resistance associated with the building elements of a structure. These building elements are required to have a fire-resistance rating of 0, 1, 2, or 3 hours, which indicates the amount of time it can continue to confine a fire and also maintain a level of structural integrity.
Table 601 of the IBC* identifies the fire-resistance requirements of building elements for the five construction types:
- Types I and II – All building elements are of non-combustible materials.
- Type III – Exterior walls are of non-combustible materials or fire-retardant wood framing with a 2-hour fire rating or less and interior building elements are of any code permitted materials, combustible or non-combustible.
- Type IV – Heavy Timber (HT) construction. Exterior walls are of non-combustible materials or fire-retardant wood framing with a 2-hour fire rating or less, and interior building elements are of unconcealed solid or laminated wood members that meet minimum dimension requirements required by the code.
- Type V – Structural elements, exterior walls, and interior walls are of any materials permitted by the code, combustible, or non-combustible.
For construction types I, II, III, and V, structural building elements must also be classified as either A or B, resulting in a total nine kinds (i.e. Types IA, IB. IIA, etc.):
- A = Protected – Structural members have additional fire rating coating or cover using spray-on, sheetrock, or other approved method that increases the fire-resistance rating by at least 1-hour.
- B = Unprotected – Structural members have no additional coating or cover.