The International Building Code (IBC) was created to provide guidelines for public health and safety from hazards associated with the built environment and to ensure compliance with the laws and regulations set by local jurisdictions. The IBC defines minimum requirements for occupancy, construction type, structural stability, Accessibility and fire protection and works as a base guideline for companion codes of Zoning, MEP, and Fire protection. It was created by the International Code Council (ICC) in 1994 as a building code that could be adopted and modified by many jurisdictions based on local climate patterns and topographical requirements.

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History and Development of the IBC

The International Building Code (IBC) was developed in the United States by merging the local building codes by the three regional model code groups. In 1972, the International Conference of Building Officials (ICBO), Southern Building Code Congress International (SBCCI) and the Building Code Administrators International (BOCA) formed the Council of American Building Officials (CABO) to develop a national building code that would serve as a base guideline for construction. The International Code Council (ICC) was formed in 1994 by merging the three regional model code groups to create the International Building Code (IBC) that could address the global AEC industry. The IBC eliminates the requirements to follow different regional guidelines and increases efficiency and profitability. The first edition of the International Building Code (IBC) was published in 2000, and it is updated in three-year intervals in compliance with the global AEC industry standards.

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Regulation Framework Building Code _©

The Building Code Structure and Focus

The International Building Code (IBC) is focused on providing requirements for the best building construction practice regarding Accessibility, structural stability, electricity and sanitation, light and ventilation, energy conservation, and safety from fire and other hazards. It serves as the building law and regulation across the United States and various parts of the world while also being valuable as non-regulatory guidelines for insurance, certification and facility management. The IBC requires compliance with the guidelines and regulations for the design and construction stages while being flexible and accessible for the architect, engineer, and code officials. The 2021 International Building Code (IBC) consists of 35 chapters that provide information on the Application and enforcement of the code, Building classification based on occupancy levels, Building Heights and Areas, Types of Construction, Fire and Smoke Protection, Accessibility and exit routes, Interior finish/environments, Energy Efficiency, Structural components, material and Design, Encroachments into the Public Right-of-Way and various reference standards. The Chapters on Occupancy, Building Height and Area Construction types, Fire and Smoke Protection, and Accessibility define the basic guidelines for the initial stages of building design.

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Assembly Occupancy CUBE KAAN Architecten _© Simone Bossi


The 3 – 4 chapters of the International Building Code are based on the Use and Occupancy Classification of building structures and the detailed requirements for these building types. The Building occupancy types are classified according to the type of use, occupancy levels and the characteristics of Combustible content, Fire Hazard and Life safety factors. The Categories of occupancy are divided as Assembly (A 1-5), Business (B), Educational (E), Factory & Industrial (F 1-2), Hazardous (H 1-5), Institutional (I 1-4), Mercantile (are M), Residential (R 1-4), Storage (S 1- 2) and Utility (U). The design requirements for load computation, Egress layout, Interior finish requirements, Use of fire partitions & barriers, Fire suppression/detection systems, ventilation and sanitation systems can only be initiated after occupancy levels are determined.  

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Type 5A Wood framed building _© Hadden Bennett – CLP News, Industry News

Types of Construction 

The Types of Construction, chapter 6 of the IBC, provides five types of classification for building structures according to the type of construction based on the properties of materials and fire ratings. Type 1A structures are of concrete construction with non-combustible structural elements of concrete and masonry. Type 1B structures use protected steel construction with non-combustible structural elements of heavy steel and Insulation. Type 2A structures use concrete or masonry with building elements composed of unprotected structural elements such as unprotected roof joists or beams. Type 3A structures use building elements made of combustible materials that are treated with 1 hr fire resistance; building elements like floors, walls and roofs are able to stop fire from spreading for a time frame of 1 hour. Type 3B structures use building elements made of combustible materials and have zero fire resistance. Type 4 building types are regarded as Millwork construction with exterior walls made of joist and masonry and interior structure of heavy timber. Type 5A structures are wood-framed buildings with all significant building elements with a 1-hour fire rating except for non-load-bearing interior walls. Type 5B building types are wood framed with zero fire resistance.

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Floor Area Ratio _© whereisthenorth

General Building Heights and Areas

The General Building Heights and Areas, chapter 5 of the International Building Code, functions as a guideline to control the height and area of new and to be built buildings structures. The building code provides Tables with specifications regarding limitations on building heights and areas based on the type of construction and occupancies, with exceptions due to the use of fire protection and industrial requirements. The specifications for building heights and areas for building groups of different occupancy are provided as required by the occupancy levels; the allowable heights and areas increase or decrease according to the safety factor of the construction type. The Type 1A structures of non-combustible structural elements of concrete and Type 1B structures of protected steel construction with non-combustible structural elements have higher allowable building height and area due to the higher safety factor. The wood-framed structures of Type 5B and Type 3B with zero fire resistance ratings have less allowable height and area as they pose a threat to the user in terms of fire ratings and structural stability.

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Building Sprinkler System _© Getty Images

Fire and Smoke Protection

The Fire and Smoke Protection Systems, Chapter 9 provides provisions to specify the Use of fire-resistant materials and safe construction practices for the design and operation of the building structure. The fire resistance standards are divided into ASTM E119 and ASTM E-84 classifications by the American Society for Testing and Materials (ASTM). The ASTM E-119 measures the fire resistance of structural assemblies of walls, floors, ceilings, beams and columns and specifies appropriate fire resistance ratings. The ASTM E-84 tests the characteristics of flame and smoke of a material like wall panelling decoration and surface insulation. The International Building Code defines four key terms: Fire partition, Fire barrier, Firewall, and Smoke protection/barrier. Fire partitions are used for partitions in separate rooms for R-1, R-2 and I-2 occupancies. Fire barriers are used as separators for mixed-used occupancy. Firewalls are used to separate different construction types, and Smoke protection/barrier are defined as a horizontal or vertical membrane that restricts the movement of smoke to ensure. The International Building Code provides Fire and Smoke Protection specifications to ensure health and safety for the building user.

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Accessibility and Means of Egress

The Means of Egress, the 10th chapter in the building code, provides information about the design, construction and arrangement of means of egress as a building structure’s exit routes and components control design feasibility and safety during hazardous situations. Architects must design buildings with protected circulation that allow occupants to travel the shortest distance possible to rooms or areas safe from potential hazards. The design of the number of exits in a contained area often depends on the number of occupants, while the distance between the exits is 1/2 or 1/3 of the diagonal length determined by the use of fire sprinkler systems. The minimum width of exit doors is 32 inches, and the height is of 80 inches. Building components of partitions and doors require fire ratings depending on the type of Use; the Shafts, Exit stairs, Fire barrier, Smoke barrier, Firewall and Fire partition need the highest fire ratings. The 11th chapter of Accessibility controls the design and construction of facilities for Accessibility to physically disabled persons. The Federal law requires all Architects to follow the Americans with Disability Act (ADA) written by the American National Standards Institute.


  1. Kelechava, B. (2023) 2021 International Building Code (ICC IBC-2021), The ANSI Blog. Available at: (Accessed: 14 October 2023). 
  2. Somers, J. (2023) The importance of the International Building Code, Crest Real Estate. Available at: (Accessed: 14 October 2023). 
  3. Nadeem, M. (no date) Building codes, standards and their importance in construction safety, LinkedIn. Available at: (Accessed: 14 October 2023). 
  4. Environmental and Energy Study Institute (EESI) (no date) Report: The value and impact of building codes, EESI. Available at: (Accessed: 14 October 2023). 

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