The NFPA 285-19 test, performed by Intertek, evaluated the fire performance of a U-STUCCO™ cladding system installed over EPS and polyiso insulation in a full-scale, two-story wall assembly. The system was subjected to 30 minutes of window and auxiliary façade burner exposure, replicating flame spread conditions typical of multi-story building fires.

Measured Performance:

• Surface stability: U-STUCCO™ resisted spalling, puffing, and delamination, maintaining full cohesion throughout the test.

• Thermocouple readings: Interior wall temperatures remained well below acceptance thresholds, with peak values averaging 100–120°C (212–248°F) — far below critical structural or ignition limits.

• Exterior surface temperatures: Even under continuous flame impingement, readings on the protected face remained within safe ranges for NFPA compliance, demonstrating controlled heat transfer.

• Vertical flame spread: Flames did not extend more than 10 ft (3.05 m) above the window header.

• Lateral flame spread: Flames did not propagate to the edges of the test specimen.

• Interior spread: No fire penetration occurred into the second-story chamber, proving complete exterior containment.

Comparison to Conventional Stucco:

Traditional stucco systems installed over EPS, XPS, or polyiso insulation typically fail NFPA 285 testing because combustible cores ignite, flames bypass cladding, and heat transfer overwhelms assemblies. In contrast, U-STUCCO™ enables foam-based wall systems to achieve NFPA 285 compliance, making it a critical solution partner for EPS and especially ICF manufacturers.

Game-Changer for the ICF Market:

Passing NFPA 285 has long been a major regulatory and insurance hurdle for the ICF industry, preventing widespread adoption in certain jurisdictions. By delivering a proven path to compliance, U-STUCCO™ removes this barrier, allowing ICF systems to be specified with confidence in residential, commercial, and high-rise projects. This breakthrough makes U-STUCCO™ not just a cladding solution, but a strategic enabler of the ICF market’s growth in wildfire-prone and code-restricted regions.

Conclusion:

The U-STUCCO™ wall assembly passed all NFPA 285 acceptance criteria with stable performance, controlled thermal behavior, and no flame propagation. These results confirm U-STUCCO™ as a code-compliant, fireproof cladding solution for exterior wall assemblies containing foam plastics, ensuring life safety, code approval, and long-term viability for both traditional projects and the expanding ICF sector.