An engineering judgment (EJ), is a drawing generated in PDF and submitted to contractors, customer, architects, or MEP consultants, typically generated by a firestop manufacturer for a customer’s jobsite-specific application. They are recommended as a solution when a jobsite condition deviates from a tested firestop system. Firestop Manufacturers must adhere to certain guidelines which are defined by local official authorities.

What is their purpose?

Contractors frequently encounter unique firestop applications at construction jobsites requiring various arrangements of penetrations through fire-rated assemblies or joints/curtain walls, different from the tested firestop systems. In such cases, customized solutions as drawings are provided for a single application or for an entire project to account for these unique applications. These drawings are prepared based on combination of multiple third-party approvals/certificates, internal test data, expertise of understanding properties of different Firestop products in respective conditions of applications.

Pic 1: Example of Engineering Judgement

How are these drawings created? 

As per the application description provided by the customer, engineering judgments are created by utilizing the most relevant/closest third-party tested and approved systems (e.g., tested acc. To UL1479, ASTM E814, ETA field of application with tests acc. to EN 1366-3 etc.). Qualified personnel creating it may include trained engineer of the Firestop Manufacturer.

Pic 2: Actual Site Application

Pic 3: Respective Engineering Judgement produced by Hilti Firestop Engineering Team

Engineering Judgments at Hilti 

Firestop systems are designed and installed to impede the passage of fire, and smoke, with some systems designed to also restrict water and sound, through construction openings in fire-rated assemblies (walls and floors).
These systems are required by all Building Codes to be tested and rated as part of an assembly in accordance with different standards of different countries:

Engineering Judgements must be prepared using the guidelines prescribed by IFC. By utilizing the complete library of test certificates published by 3rd Party Test Labs like UL and Intertek, the appropriate judgement must be derived based on interpolation of the F Ratings and/or T Ratings of the closest configuration of the job site or design details, including the penetrant types, the dimensions of openings, or the dimension of the joints or the Curtain Wall Assembly.

Highlights of a well-regulated EJ regulation or guidance paper for Evaluating Engineering Judgments 

• Use tested systems in lieu of EJs when available 
• Issued only by qualified technical personnel 
• Based upon interpolations of previously tested and closest firestop systems
• Based on the expectation that the recommended firestop system will perform as designed if subjected to the appropriate firestop test standard for the required fire-rated time 
• Limited only to the specific conditions upon which it was rendered 
• Issued for a single construction project and are not transferable to another job without review by the issuing entity
• Issued only in those locales where local codes permit their use as suitable for meeting building code requirements 

Basic EJ Presentation Requirements 

• Present in descriptive formal written form with or without detail drawings
• Indicate clearly that the recommended firestop system is an Engineering Judgement and NOT a listed system
• Identify job, contractor, non-standard conditions and required hourly rating
• Provide complete descriptions of all vital elements of the firestop system (i.e. type of assembly being penetrated, type of penetrant, size of opening, annular space requirements, etc.) 
• Include clear installation instructions for the firestop system
• Show date of issue and authorization signatures as well as issuer’s name, address and telephone number 
• Reference the number of the tested system(s) the design is based on
• Engineering Judgements must be prepared based on a single standard

Source: Engineering judgement guidelines from firestop.org


As you can see, EJ is an important and handy tool to deal with unique site conditions and ensure safety at the same time. It is also mandatory to use in case of deviations from already available tested systems. HILTI has dedicated resources to help our customer by providing EJs in quick and efficient manner. 

Steps to Requesting an Engineering Judgment

Hilti’s new digital EJ process for Firestop applications is a streamlined and self-service way to create a new EJ, submit revisions to previously completed EJs or connect with Hilti’s Fire Protection Engineering team for additional support. It’s one more way Hilti is there for you, from start to finish.

Ready for more info? Click the link below and fire off your EJ requests!

Firestop Engineering Judgments - Hilti Emirates