Factory Mutual (FM) is updating their RoofNAV system to display test pressure values instead of ratings to enhance clarity and precision in roof design and evaluation.
By making this transition, FM aims to provide a more user-friendly, accurate, and relevant tool for those involved in the design, construction, and maintenance of roofing systems, ultimately supporting better performance and safety outcomes.
Ratings are sometimes broader and less specific than test pressure values, potentially leading to ambiguities or overgeneralizations. Test pressures provide a more straightforward and precise measure of the forces a roof will need to withstand, which is crucial for engineers and architects when designing or evaluating roofs.
This change allows professionals to directly compare the required wind uplift resistance with the capabilities of the roofing system.
Displaying test pressures aligns with industry standards and codes, such as those from the American Society of Civil Engineers (ASCE) and the International Building Code (IBC). These standards specify wind loads in terms of pressure values, making it more logical and efficient for users to work with them directly.
The conversion of values in the RoofNAV system is ongoing, with completion expected in 2024.
Additional FM Updates
FM also recently implemented changes regarding gutter system testing as well, aligning with the test protocols outlined in the ANSI/SPRI GT-1 Test Standard for External Gutter Systems.
Furthermore, FM set minimum pressure requirements for FM Approval for each of the three tests conducted in gutter system testing: G-1 at 58 psf., G-2 at 101 psf., and G-3 at 62.4 psf.
This affects all gutters previously listed in the RoofNAV system, requiring retesting and relisting by July 2024.
FM Approval & ANSI/SPRI Testing: How Are They Related?
These changes spur a key question about the relationship between FM Approvals and the ANSI/SPRI standards for roof edge and gutter systems, known respectively as ANSI/SPRI/FM 4435/ES-1 (ES-1) and ANSI/SPRI GT-1 (GT-1):
The answer makes an important distinction:
The ANSI/SPRI test standards mandated by the International Building Code (IBC) are required for any edge metal product terminating a membrane on a commercial low slope roof. ES-1 testing for fascia and coping has been in the IBC since 2003 and is required by code in every U.S. state, regardless of height or usage of the commercial building. GT-1 testing for gutters has been in the IBC since 2021 and is quickly being adopted into code by states and local municipalities across the country.
There are a variety of facilities a manufacturer can utilize to test their product using the ES-1 or GT-1 test methods. If their product passes the appropriate testing process, the manufacturer can say that their product is ES-1 or GT-1 tested.
Factory Mutual (FM), on the other hand, is a building insurance provider that requires their own testing for products that they certify with FM Approval for use on their buildings. While FM utilizes the same test methods and protocols as ES-1 and GT-1, achieving FM Approval requires separate product testing performed in FM's laboratory, along with annual audits, and inclusion in the RoofNAV system.
To learn more about the ES-1 testing standard, visit our dedicated ES-1 Resource Page, and request your Perimeter Edge Metal Wind Design continuing education seminar, available in-person or virtually.
To learn more about the GT-1 testing standard, visit our dedicated GT-1 Resource Page, and request your Gutters & ANSI/SPRI GT-1 continuing education seminar, available in-person or virtually.
