After several large-scale hotel and nightclub fires in the mid-20th century that resulted in the tragic loss of life, fire safety and building design professional organizations created testing methods to rate materials based on how quickly they burn and develop smoke. Today, model codes developed by the International Code Council (IBC) and the National Fire Protection Association (NFPA) reference NFPA 285 as the test standard for exterior wall assemblies.
Development of NFPA 285 started in the 1970s in response to the increasing use of foam plastic exterior insulation in exterior wall assemblies to achieve compliance with increasingly strict energy codes. The test method evaluates how flames propagate on an exterior wall assembly subjected to a standardized fire exposure. It simulates a two-story wall assembly with an opening to simulate a window on the first-story wall, and the floors are separated by a floor assembly. NFPA 285 assesses flame propagation:
- Over the exterior wall surface
- Within the combustible core or components
- Over the interior surface from one floor to the next
- Laterally to adjacent compartments
