Engineering Judgments

An engineering judgement is a document used to assign a fire resistance rating to a project specific condition where it does not line up identically with a tested and listed 3rd party design listing. Engineering judgments are developed and supported by matching the project conditions with a system(s) that are most similar in nature. The engineering judgment outlines all the variables and provides justification for the hourly rating assigned with historical test data, technical knowledge and sound engineering principles. These judgments address unique site needs following relevant codes and standards.

Engineering judgment examples include modifications to tested firestop assemblies and curtain wall conditions not covered by a specific UL system or listed design. To be effective, the engineering judgment must be site-specific and evaluate the impact of any modifications to published fire resistance designs, firestop systems, and other tested assemblies or rated construction elements.

Engineering judgments (EJs) for firestop assemblies are utilized when a project’s unique conditions do not align precisely with a tested system. These engineering judgment firestop solutions provide a code-based path forward for maintaining fire resistance at perimeter joints, curtain walls, and other non-standard assemblies.

There are many factors that go into designing a perimeter fire containment system. What are the code requirements? What ASTM standards apply? Are the specified products correct and compatible? Have these products been properly identified and certified by third-party testing laboratories for that specific application?

Engineering judgments help address these challenges by providing a clear path forward when tested systems do not perfectly match project conditions. Because nearly every building has a unique element or design, engineering judgments play a critical role in achieving effective fire containment that aligns with both code and safety requirements.

An engineering judgment should be requested as early in the planning or design process as possible. Early coordination helps identify any conditions not covered by tested systems and allows sufficient time to evaluate, document, and incorporate the appropriate perimeter fire containment solution into the curtain wall firestop design. Request engineering judgment upfront to help prevent delays during submittals, procurement, and inspections.

It is okay to request an engineering judgment even if you do not have all the details yet. Once you complete the form, the Thermafiber Insolutions® team will contact you to understand the timing of the project details and for more information before the engineering judgment is issued.

Begin by submitting the form on this page with any available project details. The Thermafiber Insolutions® team will follow up to review the request and gather additional information as needed. In the meantime, explore the PFC Selector tool to identify a tested system, or visit the perimeter fire containment resource page to learn more about Thermafiber® mineral wool insulation products and our insulation consultants team’s approach to fire safety in modern commercial buildings.

While many firestop engineering judgments can range in cost, the Thermafiber Insolutions® team provides free engineering judgments.

The Thermafiber Insolutions® team provides all-phase consultation, technical expertise, and project-specific engineering judgments for perimeter fire containment. Our insulation consultants offer detailed CAD support, code knowledge, and a five-pronged approach to evaluating complex conditions in fire safety systems.

As the only mineral wool manufacturer that develops engineering judgments on PFC systems, our team is uniquely suited to evaluate conditions where both ASTM E2307 and NFPA 285 is a consideration. Each of our engineering judgments includes thorough installation guidelines that are valuable during design, helpful for approvals, and practical for installation by contractors as well as review by curtain wall manufacturers and third-party firestop inspectors.

The Perimeter Fire Containment (PFC) Selector is a user-friendly tool from Owens Corning designed to help identify tested perimeter fire containment systems that align with specific curtain wall configurations and code requirements. It draws from Thermafiber®’s extensive library of tested firestop assemblies and serves as a reliable starting point for developing project-specific solutions. Because most projects involve unique conditions, request an engineering judgment from the Thermafiber Insolutions team to ensure compliance and proper documentation.