FM Global’s hail classifications are used to define test requirements and expected performance when a roofing system is exposed to high-impact hail. FM uses Severe Hail (SH) and Very Severe Hail (VSH) based on FM Approval Standard FM 4473 as well as related roof assembly standards like FM 4470.

Hail performance and FM standards are important for building owners to understand. 

• For FM-insured projects, FM Global may require SH or VSH system performance depending on the building’s location.   

• SH and VSH systems might cost more upfront but can support with insurance compliance and managing insurance premiums.   

• An SH or VSH system will greatly reduce long-term loss risk of damage or a claim while providing the building owner peace of mind. 

FM System Test Methodologies for Hail Performance 

• FM hail ratings apply to the entire roof assembly, not just a single material. 

• FM’s primary concern is damage to materials that compromise waterproofing or long-term system performance, which could result in an insurance claim. 

• FM is not concerned about cosmetic dents or aesthetics; only impacts to the roofing system that would require an insurance claim and material replacement. 

Key Difference - Severe Hail vs. Very Severe Hail Systems 

• Systems that meet the requirements for FM’s Very Severe Hail (VSH) standard are the most robust and hail impact-resistant systems.