Engineering Judgments Used on Fire-Rated Assemblies
By Mike Luna, President

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Engineering judgments play a major role in ensuring the safety of buildings and their occupants.  When it comes to allowing systems installed on projects that are different than what was tested and certified, engineering judgments are an essential tool for ensuring these systems remain effective and reliable while giving the Authority Having Jurisdiction (AHJ) the confidence to allow these systems on projects they approve.

What is an Engineering Judgement?

An engineering judgment (EJ) is a report issued by a credible organization that provides an assessment of component substitutions or installation deviations from a tested assembly. Engineering judgments, occasionally referred to as engineering analyses or engineering evaluations, are developed by qualified people with expert knowledge and experience with the test method.

Manufacturers of building products spend an enormous amount of time and money to get their products tested and certified prior to use in the industry.  Unfortunately, certified systems usually are specific to what was tested, and how it was installed unless a plan is developed ahead of time with the result using an engineering judgment to extend the data for that test.  These ultimately result in listings that contain options for components other than what was tested.

So, in lieu of conducting a new test of the proposed wall assembly due to time and money, an expert will analyze the proposed assembly, the requested substitutions or installation deviations, any data associated with testing and judge its theoretical performance to determine if it also would meet the performance requirements of the test method.

The analysis considers the individual characteristics of each component material, similarities of the proposed assembly to tested assemblies, and the risks associated with the change to determine if the assembly will continue to meet the requirements of the codes and standards.

Why use an Engineering Judgement?

Architects and designers try to use fire-listed systems such as those from UL, ICC, Intertek, and other certification bodies in their designs of buildings.  Unfortunately, it is not always plausible to follow a listed assembly completely, and thus AHJs have a problem with allowing these changes unless someone with experience and knowledge in the field of fire testing can provide an engineering judgment that can assess the assemblies and determine if those assemblies would meet the test standards used in those original listings.

Engineering judgments are often used when a relatively minor deviation from a tested assembly is needed, such as substituting components in a tested assembly with a similarly performing component, when field conditions have made it impossible to install the assembly exactly as it was tested, mistakes during the construction result in an assembly that does not match the tested assembly, or no specific test can determine the as-built condition.

Engineering judgments are developed by experts to prevent these circumstances from halting a project or creating an unsafe building. These are then submitted to the AHJs for approval.

Are Engineering Judgements allowed by Code?

The International Building Code permits Engineering Judgments in Section 104.11 Alternative materials, design and methods of construction and equipment and Section 703.2.2 Analytical Methods when accepted by a building official.

Section 104.11 states that an alternative material, design, or method of construction shall be approved where the building official finds that the proposed alternative meets all the following:

  1. The alternative material, design, or method of construction is suitable and complies with the intent of the provisions of this code,
  2. The material, method, or work offered is, for the purpose intended, not less than the equivalent of that prescribed in the code as it pertains to the following:
  • Quality
  • Strength
  • Effectiveness
  • Fire resistance
  • Durability
  • Safety

Section 703.2.2 allows the use of engineering judgments established by an analytical method and shall be based on the fire exposure and acceptance criteria specified in ASTM E119 or UL 263 and shall be by any of the following methods:

  1. Fire-resistance designs documented in approved sources.
  2. Prescriptive designs of fire-resistance-rated building elements, components, or assemblies as prescribed in Section 721.
  3. Calculations in accordance with 722.
  4. Engineering analysis based on a comparison of building element, component or assemblies’ designs having fire-resistance ratings as determined by the test procedures set forth in ASTM E119 or UL 263.
  5. Fire-resistance designs certified by an approved agency.

Manufacturers, architects, builders, or installers who value proactive solutions will often navigate the complexity of fire assembly approvals by working with an expert before running any tests. An expert should discuss the client’s needs and goals so that a plan can be put in motion to gain approval by either a test plan, an engineering judgment, or both.

About Priest & Associates Consulting, LLC: With over 135+ years combined between the four partners, PAC provides consulting services for product manufacturers, architects, builders, and any other entity needing services related to fire performance of materials.  Services include help with product design, test plan development, fire listings approval plans, engineering judgments, testing oversight, and code compliance.  PAC also provides guidance to manufacturers as they navigate the North American, European, or Middle East markets.


Lieburn, Brian and Lorraine Ross. “Engineering Judgments: The Good, The Bad, The Useful.” 2019 Annual Conference Educational Sessions. October 2019. Las Vegas, Nevada. Accessed 06/30/2022.

NFPA 285 Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components. National Fire Prevention Association, 2019.

2021 International Building Code (IBC)