Since the early 20th century, the U.S. building regulations system has been based on model building codes developed by three regional model code groups and adopted piecemeal by local and state governments. For years, the regional codes and code development groups were:

1. The national codes. Developed by the Building Officials and Code Administrators International (BOCA), these were a set of building construction codes that included the BOCA plumbing code. These codes were generally used on the East Coast and throughout the Midwest. 

2. The standard codes. These were developed by the Southern Building Code Congress International (SBCCI), which included the Southern Standard Plumbing Code. The standard codes were used in the South and Southeast. 

3. The uniform codes. These were published by the International Conference of Building Officials (ICBO). It teamed up with a group of plumbing inspectors from Los Angeles, who went through a couple of name changes over the years: the Pacific Coast Plumbing Inspectors Association and the Western Plumbing Officials Association. 

In 1966, the name changed to the International Association of Plumbing & Mechanical Officials (IAPMO); the organization has been promoting the Uniform Plumbing Code (UPC), originally published in 1945. ICBO, which published the Uniform Building Code, referenced the UPC as its plumbing code. It was used primarily throughout the West Coast and across portions of the Midwest.

One model construction code 

In 1972, BOCA, SBCCI and ICBO created the Council of American Building Officials (CABO) to develop a national building code for residential one- and two-family home construction. It was needed to address minimal health and safety requirements for residences. 

The CABO One and Two-Family Dwelling Code was developed with the federal government’s backing but was adopted by only a handful of U.S. jurisdictions. Instead, it was used for federal housing projects, as many jurisdictions preferred to adopt the regional model building codes. 

In 1994, the three groups agreed to merge as the International Code Council (ICC) and develop a comprehensive set of building codes with no regional limitations: the International Codes (or I-Codes). The first code slated for development was the International Plumbing Code. After two drafts and code hearings, it was officially published in 1996. During that time, the three groups were working on developing all the other codes for publication in the 2000 edition of the I-Codes. 

Since then, a new edition of the I-Codes has been published every three years. By the year 2000, ICC had completed the International Codes series. It ceased development of the original model codes in 2003 in favor of the new International Codes, following the 2002 ratification of the merger of the three model code organizations.

Several free trade developments led to the discussions of the merger of and the development of the I-Codes: the ratification of the North American Free Trade Agreement in 1994; the formation of the European Union (EU) in November 1993; and the EU’s efforts to unify standards in Europe for building design, construction and materials across the European Single Market. (The Eurocodes started in the 1980s with civil/structural and concrete, and now include all codes scheduled for 2026 publication.) 

The one-code initiative

The plumbing and mechanical industry tried to develop a single model plumbing and mechanical code through the One Code Summit, a joint effort between ICC and IAPMO around 2005. Meetings were held in several cities across the country to discuss combining the two plumbing and mechanical codes into one code. That effort was unsuccessful when they could not work out the logistics of who would control the code development.

Many of us experienced the dilemma of designing to comply with multiple plumbing codes. Plumbing and mechanical design professionals who worked on projects across the country were constantly going through a shelf full of plumbing and mechanical code books of different vintages. Electrical engineers, however, used the same electrical code nationwide, no matter where the project was located. 

Plumbing and mechanical design professionals had to adapt buildings for different locations across the country, making significant design, detail and specification changes to comply with regional plumbing and mechanical code requirements. Science, engineering and the laws of physics do not change when you cross state lines or city limits; it is only politics and the adopted codes that change. This highlighted the need for a single model plumbing and mechanical code, as the electrical industry had.

2027 model codes nearing completion 

In the United States, the major model code organizations are wrapping up their three-year code update cycles for the 2027 model code editions. These codes should be ready in the coming months for jurisdictions to review and comment, and then include local ordinances for the adoption of the codes. 

The model codes are the minimum health and safety building code requirements developed through an open public hearing process, with several rounds of public hearings and voting on the minimum code requirements for health and safety, and for affordability.

The International Code series 

The I-Codes, developed by the ICC, are a family of 15 coordinated building codes that include health and safety considerations and minimum requirements to help ensure the design and construction of safe, sustainable and affordable structures. You can find the latest codes (2024) at https://bit.ly/3N7ieRl.

The Uniform Code series 

IAPMO develops the Uniform Code series (the Uniform Plumbing Code; the Uniform Mechanical Code; the Uniform Solar, Hydronics and Geothermal Code; and the Uniform Swimming Pool, Spa and Hot Tub Code), as well as the Water Efficiency and Sanitation Standard.

These are available to state and local jurisdictions for adoption and to international countries for the development of their model codes. 

NFPA Code series

The National Fire Protection Association (NFPA) publishes NFPA 70 National Electrical Code, used by both major model code organizations. The NFPA also publishes NFPA 54 National Fuel Gas Code and the NFPA 101 Life Safety Code. They are used alongside IAPMO’s uniform plumbing and mechanical codes and the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) standards for energy efficiency. They can be locally adopted by jurisdictions that choose to adopt the uniform codes and other standards that form the basis for state/local building construction ordinances, laws and codes in their jurisdictions. 

NFPA initially looked at joining with ICC to develop the International Fire Code (IFC). The joint effort fell apart after the first draft of the IFC document was completed, when a dispute arose between the code and fire officials over building fire safety construction vs. retroactive enforcement issues and which code language applied. 

After several failed attempts to find common ground with the ICC, the NFPA withdrew from participation in the development of the International Codes and joined with IAPMO and ASHRAE to create an alternative set of model codes. First published in 2002, the Comprehensive Consensus Codes included the NFPA 5000, a building standard published with mandatory language to be used as a building code. 

The origins of the document were the construction standards for the Reedy Creek Development Authority in Lake Buena Vista, Florida — developed by engineers for the design and construction of Florida’s Walt Disney World. 

NFPA started developing its model building code, NFPA 5000 Building Construction and Safety Code, in March 2000 in response to the I-Codes development. It launched the initiative after discussions with IAPMO, which was left without a building code after deciding not to follow ICBO to the ICC. To do so would have meant giving up control of the plumbing and mechanical codes. 

A major hurdle was that both had fuel gas codes. It was agreed that the NFPA fuel gas code had been around much longer and was more widely accepted. However, IAPMO still wanted to keep fuel gas under its wing. An agreement was made that NFPA would control the development of the fuel gas code at its hearings; IAPMO would simply reprint the NFPA code language with references to the appropriate sections in NFPA 54.

The NFPA’s move to introduce a competing model building standard received strong opposition from groups such as the American Institute of Architects (AIA), the Building Owners and Managers Association (BOMA), the National Association of Home Builders and international groups. 

After several unsuccessful attempts to encourage cooperation between NFPA and ICC to resolve their concerns over code development control, a number of organizations — including AIA, BOMA and dozens of commercial real estate associations — founded the Get It Together coalition. It repeatedly urged NFPA to abandon code development for NFPA 5000 and to work with ICC to integrate other NFPA codes and standards (such as NFPA 70 and NFPA 54) into a single, coordinated family of codes. 

This has not happened, so our bookshelves are still full of multiple code books from various organizations. 

All these developments caused code officials, contractors, design professionals and manufacturers to push for a single nationwide set of building codes in the United States. This would save time referencing the appropriate code for a jurisdiction, and users and manufacturers would waste less time and money complying with the different code and standard provisions of all the regional codes.

ASHRAE standards as codes

ASHRAE, in collaboration with other organizations, publishes several standards that serve as the basis for adopted building codes. These are not technically codes themselves, but are, in some cases, adopted into law by state and local jurisdictions. 

The primary ASHRAE standards that, in some jurisdictions, function as building codes are:

• ASHRAE/IES Standard 90.1: Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings. This is the most widely adopted and is the benchmark for U.S. commercial and high-rise residential building energy codes. 

• ASHRAE Standard 90.2: Energy-Efficient Design of Low-Rise Residential Buildings. Residential buildings, three stories or less.

• ASHRAE Standard 62.1: Ventilation for Acceptable Indoor Air Quality 

• ASHRAE Standard 62.2: Ventilation and Acceptable Indoor Air Quality in Residential Buildings 

• ASHRAE Standard 100: Energy and Emissions Building Performance Standard for Existing Buildings 

• ASHRAE/ASHE Standard 170: Ventilation of Health Care Facilities. This standard establishes requirements for ventilation in hospitals, nursing homes and other healthcare facilities. 

• ASHRAE Standard 189.1: Standard for the Design of High-Performance Green Buildings. Developed in partnership with the ICC and the U.S. Green Building Council, this standard establishes comprehensive requirements for sustainable building design, construction and operation.

Key model code development organizations

• American Society of Heating, Refrigerating and Air-Conditioning Engineers (www.ashrae.org). Develops energy efficiency standards, such as ASHRAE 90.1, Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings, often used for commercial buildings.

• Facilities Guidelines Institute (www.fgiguidelines.org). Provides guidelines for healthcare facility construction. These guidelines become legally binding when adopted by states, federal agencies (such as the Health and Human Services agency) or referenced in local building codes, serving as standards for licensing and accreditation. 

Enforcement happens through state departments of health, building code officials and accreditation bodies that check compliance during new construction or renovations. They use the guidelines as the benchmark for patient safety and facility standards, often as law or an alternative compliance path.

• International Association of Plumbing and Mechanical Officials (www.iapmo.org). Creates the Uniform Plumbing Code and Uniform Mechanical Code.

• International Code Council (www.iccsafe.org). Develops the widely adopted International Building Code (IBC) for most buildings, the International Residential Code for homes and codes for plumbing, mechanical and energy.

• National Fire Protection Association (www.nfpa.org). Publishes the National Electrical Code (NFPA 70), essential for electrical systems and fire protection codes.

How code adoptions work

1. Model codes created. Organizations develop model codes through a published hearing process in which they call for code change proposals, meet to discuss the merits of the proposals, and vote on whether to accept them. A comment period allows proposals to be modified, followed by a final voting process for approval or disapproval. Sometimes they develop technical guidelines or standards, too.

2. Adoption by jurisdictions. States, counties and cities review these model codes before adopting them, often modifying them to fit local conditions. When a model code is adopted by a jurisdiction as part of an ordinance, it becomes the law in that jurisdiction and is legally binding.

3. Enforcement. Once adopted, these building codes are enforced by state and local building code officials and become enforceable building codes with penalties for noncompliance. 

Proposed changes to the 2024 codes for 2027

The schedule for both model codes follows a three-year code development cycle (2024-2026), culminating in final hearings in early 2026 and the publication of the 2027 model codes in mid-to-late 2026. The model code organizations strive to publish the codes early enough to allow jurisdictions time to review the codes and propose amendments and ordinances for adoption before 2027. 

For the latest information on each model plumbing code, check their code development organization’s websites.

The 2027 I-Codes remaining schedule:

• April 2026: Public comment hearings (joint for Group A and B);

• Mid-to-late 2026: ICC voting members finalize the 2027 Group B codes.

The ICC invites dedicated volunteers to apply for committee positions in the 2030 (2027–2029) code development cycle. By serving on these committees, you can help shape the 2030 I-Codes and advance building safety through the model codes used by your communities and others globally. The process is divided into two groups: Group A and Group B, with a single set of joint hearings and voting in the final year. 

Applications for ICC committee members are due by April 1, 2026. For more information, visit www.ICCsafe.org.

The key Committee Action Hearings (CAH) dates for the IPC 2030 codes are: 

April 13–22, 2027: CAH No. 1 for Group A codes (IBC, IPC, IFGC, IMC, etc.), Dallas and Frisco, Texas

September 15–22, 2027: CAH No. 2 for Group A codes, Reno, Nevada

May 1–9, 2028: CAH No. 1 for Group B codes

October 18–27, 2028 (tentative): CAH no. 2 for Group B codes

April 22–May 1, 2029: Combined Groups A and B public comment hearing

Mid-2029: Post public comment hearing; combined Groups A and B online governmental consensus voting

Mid-2029: After voting; final actions posted by the ICC board 

For detailed information on the specific codes within each group and to track the current development status, visit the ICC’s code development page at https://bit.ly/3Z2t1il.

The key dates for the 2030 UPC development schedule are:

January 30, 2026: 2030 UPC/UMC technical committees applications due

July 3, 2026: Call for proposals for the UPC  

January 8, 2027: Deadline for submission of proposals  

April 2, 2027: Distribute proposals to committee (ROP monograph) 

May 3-5, 2027: UPC Technical Committee meetings (location TBD) 

May 6-7, 2027: UMC Technical Committee meetings (location TBD)

May 28, 2027: Initial ballots to Technical Committee 

June 11, 2027: Circulation of comments on ballots 

June 25, 2027: Final closing date for ballots 

July 7, 2027: Technical Correlating Committee meeting  

August 9, 2027: Distribution of Report on Proposals (ROP) 

September 7, 2027: Call for comments      

September 30, 2027: IAPMO Assembly Consideration Session (Honolulu, Hawaii) 

For more information, visit https://bit.ly/4sr63iy.