EPDM roofing assemblies can be designed to meet Underwriters Laboratories (UL) and Factory Mutual (FM) fire classifications. The most common classifications are:
- Class A (highest fire resistance)
- Class B
- Class C
Factors Affecting Fire Rating
It’s important to note that there are no fire ratings for EPDM membranes alone. The fire rating applies to the entire roofing system, which includes:
- Roof deck material
- Insulation
- EPDM membrane
- Roof slope
- Other components
The specific combination of these elements determines the overall fire rating.
Achievable Ratings
- EPDM systems can achieve Class A fire ratings, which is the highest level of fire resistance.
- Some EPDM manufacturers offer UL Class A fire ratings and FM Global wind uplift ratings up to 1-990 over concrete and 1-255 over steel for their systems.
Fire-Retardant EPDM
Some manufacturers produce fire-retardant (FR) EPDM membranes specifically designed for enhanced fire resistance. These FR-rated membranes can achieve higher slopes while maintaining Class A ratings compared to standard EPDM.
Testing and Certification
EPDM roofing assemblies undergo rigorous fire testing to obtain their classifications. This includes tests for flame spread, burn-through resistance, and flying brand resistance.
Long-Term Performance
While initial fire ratings are important, it’s also crucial to consider long-term fire resistance. Some roofing materials may lose fire resistance over time, but EPDM generally maintains its fire-resistant properties well throughout its lifespan.