An engineering judgment (EJ) is a drawing typically generated in PDF format by a firestop manufacturer for a jobsite-specific application. They are generally submitted to contractors, customers, architects, or MEP consultants. EJs are recommended as a solution when a jobsite condition deviates from a tested firestop system. When creating EJs, firestop manufacturers must adhere to certain guidelines which are defined by official authorities.  

What is their purpose?

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

Image 1: Example of an engineering judgement (EJ)

How are these drawings created? 

After an application description has been provided by the customer, engineering judgments are created by using the most relevant / closest third-party tested and approved systems (e.g. tested or assessed according to AS 1530.4 and AS 4072.1). Qualified personnel creating it the EJ may include a trained engineer of the firestop manufacturer.

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 the Australian NCC 2022 to be tested and rated as part of an assembly in accordance with AS 1530.4 and AS 4072.1.

Presently, there are no particular local and global guidelines around EJs in standards other than ASTM, but the use of EJs is widely accepted. The testing and rating process ensures that each specifically designed system will maintain or exceed the hourly fire rating, as tested, for which it was approved.

Characteristics of a well-regulated EJ 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 for which it was designed 
• Issued for a single construction project and is 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 detailed 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
• Provides 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.) 
• Includes clear installation instructions for the firestop system
• Shows date of issue and authorization signatures, as well as issuer’s name, address and telephone number 
• References the number of the tested system(s) the design is based on
• Must be prepared based on a single standard

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

Steps to request an engineering judgment

1. Gather all required project and application information
2. Download an Engineering Judgment Request Form and fill this online form >>> click here. Fill out the required fields marked with an asterisk (*). Accurate information helps expedite your request
3. Please also include a sketch of your firestop application along with your Engineering Judgment Request Form. A member of our Firestop Team will be in touch

Source: Engineering judgement guidelines from firestop.org