Insulated Metal Panels and NFPA 285
An Insulated Metal Panels (IMP) is a panel assembly comprised of a rigid foam plastic insulation core sandwiched between two sheets of coated metal facers. IMPs can be formed in a variety of sizes and shapes and are typically used on walls and roofs. This article will focus on the use of IMPs on exterior wall assemblies. Figure 1 provides a cut-away view of an IMP.
IMP panels are required to be tested in accordance with NFPA 285 and specific IMPs have been tested and meet the conditions of acceptance of NFPA 285. Since every variation of a wall system cannot be tested, and based on the discussions above, if the “basic” IMP panel system meets NFPA 285, minor variations in items such as caulks, trim, window details, and joints can be allowed without retesting or an analysis.
When required, an engineering judgment can be used to evaluate the NFPA 285 fire performance of variations from a tested system when it is appropriate. These engineering judgments have been accepted by building code officials and the authorities having jurisdiction (AHJ) for many years on a variety of projects throughout the USA.