The Importance of Engineering Judgments for Perimeter Fire-Containment Systems

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Sponsored by Owens Corning

Perimeter fire-barrier system EJs should:

  1. Not be used in lieu of tested systems when tested systems are available;
  2. Be issued only by a firestop manufacturer’s qualified technical personnel or in concert with the manufacturer by a knowledgeable registered professional engineer, fire-protection engineer, or independent testing agency that provides listing services for firestop systems;
  3. Be based upon interpolation of previously tested firestop systems that are either sufficiently similar in nature or clearly bracket the conditions upon which the judgment is to be given. Additional knowledge and technical interpretations based upon accepted engineering principles, fire science, and fire testing guidelines (e.g., ASTM E 2032: Standard Guide for Extension of Data from Fire Endurance Tests, ULC Subject C263E: Criteria for Use in Extension of Data from Fire Endurance Tests, or ASTM E2750: Standard Guide for Extensions of Data for Penetration Seals) also may be used as further support data;
  4. Be based upon full knowledge of the elements of the construction to be protected and the understanding of the probable behavior of that construction and the recommended firestop system protecting that construction if it was subjected to the appropriate standard fire test method for firestops for the rating indicated on the EJ;
  5. Be limited only to specific conditions and configurations upon which the EJ was rendered and should be based upon reasonable performance expectations for the recommended firestop system under those conditions; and
  6. Be accepted only for a single, specific job and project location and should not be transferred to any other job or project location without thorough and appropriate review of all aspects of the next job or location’s circumstances.

The IFC also provides basic information on how the EJ should be written and presented.

Proper perimeter fire-barrier system EJs should:

  1. Be presented in appropriately descriptive written form with or without detail drawings where appropriate;
  2. Clearly indicate that the recommended firestop system is an EJ;
  3. Include clear directions for the installation of the recommended firestop system;
  4. Include dates of issue and authorization signature as well as the issuer’s name, address, and telephone number;
  5. Reference tested system(s) upon which design (EJ) is based on;
  6. Identify the job name, project location, and firm EJ is issued to along with the non-standard conditions and rating supported by the EJ;
  7. Have proper justification (i.e., UL, ULC, Intertek, SWRI, or other independent laboratory system(s) and or opinions); and
  8. Provide complete descriptions of critical elements for the firestop configuration. These should include, but are not limited to, the type of assembly, the required fire rating, and a detailed description of the perimeter fire-containment system, including details which demonstrate its compliance with the six design principles outlined earlier in this course.


The design professional has the sobering responsibility of designing buildings that comply with today’s rigorous building codes and, to the greatest extent possible, protect the life safety of the occupants within. The fire risk associated with curtain-wall systems is a serious issue that must be addressed, and although tested perimeter fire-containment systems can mitigate the problem, designed systems rarely match these perfectly. Most of the time, an EJ is required to compare the designed system to a listed and tested one. The design professional must be able to obtain a high-quality EJ to ensure the safety and code compliance of the systems they design. Having a foundational understanding of what makes effective perimeter fire containment and what to look for in a quality EJ is key. Fortunately, the architect is not alone, but is part of a team for the proper design, evaluation, and installation of the perimeter fire-containment system, and, ultimately, the life safety of the buildings they collaboratively create.


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Originally published in Architectural Record
Originally published in December 2019