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Major Revisions to Section 104 of the 2021 IMC: What You Need to Know
The 2021 edition of the International Mechanical Code (IMC) brought a significant overhaul to Section 104, and it’s not just a simple update. This section, which addresses the authority and duties of the code official, including the evaluation of alternate methods and materials, hadn’t seen major changes since the first edition in 2000. With industry practices evolving over the last 20 years, it was time to make adjustments to better reflect the realities of today’s construction environment.One of the key reasons for this rewrite is the shift in how products and materials are evaluated. Originally, the code envisioned a project-by-project approval process, where designers submitted substantiating tests, calculations, or analyses with each permit application. Over time, however, the industry has moved toward a more efficient system. Now, evaluation reports for products or methods are used across many jurisdictions and for multiple projects, saving time and resources for everyone involved. Section 104 needed to catch up with these practices.
The rewrite also aims to standardize the language and organization of this section across all relevant codes, including the IMC, IFGC, IPC, ISPSC, and IPSDC. While some nuances specific to each code are retained, the goal was to create a more unified approach to the duties and responsibilities of the code official. This includes how alternate methods are reviewed and approved, and it now clearly differentiates between evaluations from accredited agencies and those provided by engineers or other professionals.
While this new version of Section 104 reflects modern procedures, it also keeps an important provision from earlier versions: the ability for designers to apply for one-time approval of methods or materials not addressed by the code. This is where “research reports” come in. When a method or material isn’t directly covered by the code, the code official still needs enough information to ensure compliance with the code’s intent. These research reports give flexibility to both designers and code officials to consider innovative solutions while maintaining safety and code compliance.
This change was part of a broader effort to bring consistency across all the I-Codes, so similar revisions are being made in other related codes, including the IBC, IEBC, IRC, and IPMC. The goal is to streamline the enforcement process, improve clarity, and make sure the codes reflect how they are actually applied in practice. Despite some delays in getting this package reviewed by the PMG Code Action Committee, the final result ensures that the content and formatting are now standardized across the board.
In short, the 2021 revision to Section 104 of the IMC represents a much-needed update to align the code with current industry practices while still providing flexibility for one-time approvals when necessary. For those working with alternate methods and materials, this change should help simplify the process and make it easier to navigate the evolving landscape of building codes.