Building Codes

ACCA helps contractors comply with building codes. And we help code officials understand HVAC.

The purpose of building codes are to guide government agencies in meeting their minimum obligations to protect the general welfare of the population they serve. Codes are designed to prevent damage to property, as well as injury or death to persons, and these objectives are accomplished by applying accumulated knowledge to the avoidance, reduction, or elimination of definable hazards.

Codes generally apply to the built environment and, when adopted by the pertinent authority, become lawful requirements that mandate compliance. An authority may write its own code document or may adopt other code documents. Different states and/or municipalities are free to adopt different codes.

Standards are usually regarded only as recommendations that do not have the force of law, unless the standard is adopted by the authority having jurisdiction. It is common for sections of a local code to refer to nationally recognized standards. In many instances, entire sections of the standards are adopted into the code by reference, and then become legally enforceable.

There are three main organizations in the United States who write codes that impact the indoor environment industry: IAPMOICC and NFPA.

Current Activities

Industry Involvement Needed . . . Time for Another Code Change Cycle for Both ICC and IAPMO Codes!

With the ink barely dry on their respective 2021 editions, the International Code Council (ICC) and the International Association of Plumbing and Mechanical Officials (IAPMO) have commenced a new 3-year code change cycle.  The ICC’s “Group A” codes are first up for next year (2021), which include their mechanical, plumbing, fuel gas, and residential codes.  The ICC energy code revision cycle will take place during 2022.  The IAPMO Uniform Mechanical and Plumbing Codes are also up for revisions next year.  The ICC due date for code change submittals is January 11, 2021, and the IAPMO due date for proposals is January 4, 2021.  These code change cycles will result in the publication of the 2024 editions. 

ACCA’s Involvement

The above activity falls under the scope of the ACCA Codes Subcommittee, which takes a proactive role in developing proposed code changes based on member input, plus reviewing other code changes published for public comment to provide contractor guidance.  For the above code development cycles, the Codes Subcommittee is seeking CONTRACTOR input on changes needed for the 2021 ICC and IAPMO codes.  If there are areas of those codes that you feel need improvement, or “fixing,” please send your ideas or suggestions to ACCA staff as soon as possible.  Your suggestions do not have to be in formal code proposal language, just let us know where (and why) the problem or improvement is needed and the ACCA Codes Subcommittee will consider developing a proposal.  Please send your ideas to

Some proposals that the Subcommittee is working on are:

  • Add a requirement to the International Residential Code – Mechanical to install pull-down stairs or a stairway to access equipment installed in attics for servicing. Such a requirement exists in the State of Georgia as an amendment to their mechanical code.

  • Add a requirement to the International Property Maintenance Code (IPMC) to comply with ACCA Standard QM4, Maintenance of Residential HVAC Systems.

Information for Contractors

ACCA Template to Request Jurisdictions Not to Adopt GFCI Protection for Outdoor HVAC Equipment in 2020 NEC – Nuisance Trip Issue

The 2020 Edition of NFPA 70, the National Electrical Code (NEC) now requires ground fault circuit interrupter (GFCI) protection for outdoor outlets, which would include disconnects for HVAC/R condenser units and other outlets. Read more here.

ACCA Releases Template to Request Jurisdictions To Exempt Leak Testing of Ducts Within Thermal Envelope – New Energy Code Requirement 

The ACCA Codes Subcommittee developed a Template for members to request an exemption from this testing requirement.   Different states adopt codes at different times, Missouri recently adopted the IRC even though it is not published.  A useful tool to determine which code is adopted and enforced in your state can be found on ICC’s website. Read more here. 

Adoption of ICC Codes in the U.S.

The International Code Council’s (ICC) website details “State Adoptions” and “Local Adoptions” of the varied ICC codes (e.g., IBC, IECC, IMC, IPC, IRC, etc.) across the U.S. ICC’s “State Adoption” link provides information as to when the codes where adopted as well as to the key code contacts within a State. ICC’s “Local Adoption” link details county-by-county breakdowns of which version of the varied ICC codes are utilized in a given county by State. Learn more here.

A number of substantive changes have been made during ICC’s last code change cycle, which culminated in the publication of the 2021 editions. Below is a summary of those changes.  More summaries will be added as ICC publishes their new editions.

Summary of Significant Changes in the 2021 Edition of the International Mechanical Code

Reciprocal ICC Membership for ACCA Members

Through a special agreement between ACCA and the International Code Council (ICC), ACCA Members may apply for a free membership to the Code Council. No other building code association offers you more I-Code resources to help enhance your code knowledge. Take Advantage of These Code Council Benefits:
  • Discounts on ICC certification renewals
  • Best pricing on I-Code resources and online training
  • Free access to ICC’s online Career Center
  • Discounts up to 25% off code publications
  • Opportunities to participate in member councils, committees and more
To receive these benefits, download, complete and submit this simple application.

Codes 101 Brochure

This brochure covers the basics of codes and standards and is aimed at providing contractors with a general understanding of these issues so that they can become more involved in the code development processes that affect the HVAC industry. Download it.

Residential System Design Review Form

ACCA has crafted an easy-to-use evaluation of HVAC system design elements in the pertinent building codes. Download it.

Computing Infiltration Loads based on a Target Envelope Leakage Requirement

This Technical Note shows how to convert a maximum code allowable leakage limit (say, 3 or 5 ACH 50 per the ICC International Energy Conservation Code) to a Manual J infiltration CFM value, and then to the infiltration load contributions (Btuh) for sensible heating, sensible cooling, and latent cooling. It also discusses the use of blower door data for one or more test points. Download it.

ACCA Codes Committee (committee members only)

Get involved in ACCA’s Codes Committee and make a difference in the development and adoption of good building codes. For more info about becoming involved in the Codes Committee and ACCA's building code efforts, contact

Information for Code Officials

Residential System Design Review Form for Code Offices

ACCA provides a “review form” (that may be customized by code officials for the relevant ICC and IAPMO codes) that can serve as the cover page to a contractor’s permit submission.  Blank forms as well as completed examples and instructions to contractors can be found here.  

Brochures for Code Officials

ACCA has developed several brochures which help code officials verify residential load calculations, duct design and equipment selection in accordance with Manuals J, D, and S. While it’s not practical for code officials to verify every single aspect of these submissions, these brochures offer checklists for a simplified verification process. Download them.

Load Calculation Software

An important warning notice for code officials about the dangers of inappropriate load calculation software. Download it.

ICC PMG Membership Council

Visit the International Code Council's (ICC) Plumbing Mechanical Gas (PMG) Membership Council webpage for other resources like CodeNotes, High School Technical Training Program Toolkit, and technical partners information.

Bob's House

Bob's House - A case study for understanding the residential HVAC design process as described in the ACCA residential technical manuals. The book begins with the building plans and follows the process through the completion of the system design. Also included are useful appendices that explore what would happen to Bob's house if he were in a different city, or if his builder had used different building materials , as well as the impact of other possible scenarios and other possible variations. Other appendices discuss different equipment types, duct challenges, and an illustrative example of how information might be presented for a permit application. Click here to learn more

Video Training for Code Officials

ACCA has developed a three-part video series that aims to help code officials better understand the three main aspects of a proper residential HVAC system design: a load calculation, selecting the appropriate equipment, and proper duct sizing.  The basis for the videos are the code-referenced ACCA Manual J, Manual S, and Manual D.  The videos do not comprise a design course, but instead provide an overview of the design process and presents ACCA-recommended verification points.  This will better enable code officials to verify that a system was designed correctly.


Looking for CEUs?  

ACCA is now an ICC Preferred Education Provider. Earn .2 CEUs by passing a 30 question online exam and earn your course certificate.
Click here to learn more and sign up.

ACCA in Building Codes

For years, ACCA's technical manuals and standards have been an integral part of the national model building codes' requirements for proper HVAC design.  The following model codes currently reference, or have in the past referenced, ACCA's various design manuals and standards:

  • IAPMO's Uniform Mechanical Code
  • IAPMO's Uniform Swimming Pool, Spa, and Hot Tub Code
  • ICC's International Residential Code
  • ICC's International Energy Conservation Code
  • ICC's International Mechanical Code

To see the detailed references in each model code, including section excerpts, please see the document for the specific cycle:

ACCA Codes Development Position Statement

The model building codes are intended to ensure that our buildings are safe, sustainable, affordable, and resilient; they contain the minimum safeguards for their construction. Though the distinct code-promulgating organizations have different procedures for the development of their various codes, they all include provisions for the call for, publication of, discussion about, and voting on public code change proposals. These code change proposals are (ideally) intended to refine the codes by addressing gaps or moving them forward in their stated mission. 

In practice, however, the various players in the code development arena (code officials, design professionals, code consultants, trade associations, builders/contractors, manufacturers/suppliers, and government agencies) may submit code change proposals that are intended to give a specific process, product, or organization special consideration in the administration of a code. 

As a national trade association that represents more than 60,000 professionals and 4,000 businesses in the indoor environment and energy services community, ACCA does not support changes to the model codes that would limit a designer's options to provide quality service to their customer. ACCA recognizes that any aspect of a building system may be installed incorrectly due to subpar field practices. However, these installation issues should be addressed through the development of consensus standards on the specific issue, and not by code banning a viable design alternative.