Fire Performance
Fire Performance

Polyiso – A Leader in Fire Performance

All construction materials, including foam plastic materials like polyiso insulation, must provide a suitable margin of fire safety. Codes and test standards set the minimum level of overall building fire safety as well as minimum levels of fire performance for specific construction materials and assemblies. These codes and standards are developed and maintained through consensus-based processes. Groups of experts and other stakeholders that include representatives beyond product manufacturers contribute to the various code and standard development processes.

Polyiso insulation delivers a high level of inherent fire resistance when compared to other foam plastic insulations due to its unique structure of strong isocyanurate chemical bonds. These bonds result in improved high temperature resistance (up to 390 degrees F; more than twice the temperature resistance of other building insulation foams) which in turn leads to enhanced fire resistance. In addition, polyiso products form a protective surface char when exposed to a sufficient flame source. This physical property is exhibited in the ASTM E84 or “Steiner Tunnel” test, where polyiso insulation test specimens remain intact (i.e., do not melt or drip) during the test’s fire exposure. This performance characteristic further enhances polyiso’s fire resistance, especially in terms of flame spread and flashover potential.

Roofing Applications

Commercial roofs are subjected to full assembly fire testing; individual material components like polyiso insulation are required to meet additional product-specific fire performance criteria. Polyiso remains the only foam plastic insulation product for direct application to steel roof decks to earn FM Approval for Class 1 Roof Systems. An FM Class 1 designation means the roof assembly has been subjected to a series of tests in addition to external and internal fire exposure, including wind uplift, water leakage and impact resistance. As a result, direct-to-deck assemblies containing polyiso insulation meeting NFPA 276 (FM 4450) or UL 1256 can be installed without a thermal barrier. To date, hundreds of thousands of assemblies have gained approval under these test standards.  

For additional technical information on the fire safety of roofing applications, please consult PIMA’s Technical Bulletin 100 Series – Roofing.  

Wall Applications

Exterior walls of any height on commercial buildings (IBC Types I-IV) that contain polyiso insulation (or any other foam plastic insulation) must be evaluated for full-assembly fire performance per NFPA 285. Foam plastic insulation products are also required to meet additional product-specific fire performance criteria for flame spread and smoke development. Polyiso’s exceptional fire performance provides building designers with important flexibility when selecting other components of exterior wall systems, including façade or cladding materials. A wide-variety of exterior wall assemblies that combine polyiso insulation with MCM panels, brick and other popular materials have passed the rigorous, two-story NFPA 285 fire test. Note: Wall systems containing polyiso insulation may be subject to other fire tests and building code requirements. Consult your local building code and manufacturer installation instructions for more details.

For additional technical information on the fire safety of wall applications, please consult the Technical Bulletin 400 Series – Commercial Walls.