The specific and detailed nature of NFPA 285 test data and reports can complicate potential distribution of the information. Test reports often contain proprietary information that is not appropriate for publication. Manufacturers also find misinterpretation or misuse of test data is likely when those who are unfamiliar with the test method and fire science review these test reports and data. In practical application, testing efforts will evaluate “worst case” configurations to establish baseline assemblies for subsequent analysis and extension of test results to similar and more robust configurations.
The last several editions of the NFPA 285 test method have seen several revisions to test assembly design and reporting requirements. For example, the 2019 Edition contained several revisions that included:
- Requirements for test specimens to have at least one horizontal and one vertical joint/seam of the exterior veneer within a defined area above the window opening.
- A new prescribed procedure and materials to generically close the window head, jambs, and sill, as well as the option to use a specific closure/construction detail(s) per the manufacturer’s instructions.
- Requirements for the test report to contain drawings and a description of the construction details around the window.
Designing compliant wall assemblies
When designing an exterior wall assembly required to comply with NFPA 285, it is best to consider options from the very beginning. The design will need to meet aesthetic, energy, and moisture management requirements in addition to fire safety. Once all the performance goals of the assembly are determined, a designer can identify the materials and the configuration to use. Although one might find NFPA 285 assembly compliance information for the initial design, some flexibility may be needed when specifying materials for the project.
When determining the components for the wall design know that most assemblies will contain materials that will prompt NFPA 285 testing and compliance of the wall assembly, such as foam plastic insulation, combustible water-resistive barriers (WRBs), metal composite material (MCM) panels, and high-pressure decorative exterior-grade compact laminate (HPL) panels. The type, amount, and location of combustible components is often limited based on the tested assembly. These variables must be considered when determining NFPA 285 compliance.
Locating compliant assemblies
There tends to be two places where one may find test and design information pertaining to NFPA 285, manufacturers, and third-party directories. Manufacturers are likely to have the most current information and flexibility to evaluate potential wall designs against their available testing and engineering analyses and extensions. When conducting third-party directory searches, searches based on the various components, or products may be necessary to find a listed assembly conforming to the intended design.
