This is the #1 barrier to entry for foam cores in Mass Transit (Trains, Subways) and Architecture. Standard Styrofoam (EPS) or Polyurethane produces thick black toxic smoke and melts into flaming drips.
- Compliant Options: You must use Phenolic Foam (which chars into a protective carbon layer) or specialized Fire-Retardant PET.
- Market Note: A standard wall panel for a subway car might cost 5x more than a construction panel solely because of the FST-certified core material.

