Q: Can you explain recent changes to the National Fire Protection Association test standard known as NFPA 285, and how they might impact contractors?
A: Over the past few years there has been a rash of serious high-rise structure fires that raised awareness for the need to regulate life safety principles in the exterior walls. There have been 12 significant high-rise fires dating back to 2008. At issue is the spread of the fire vertically up the building’s exterior. During the 1990s, a fire test standard was developed in the United States and code mandated to minimize the potential for this to occur. In 2019, the test standard was revised, and the resulting changes will impact the contractor involved in exterior wall construction.
The test standard is titled “NFPA 285 Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components.” The test simulates a two-story exterior wall that is separated by a floor assembly. The lower floor has an opening of a specific size in the exterior wall. A fire with a controlled fuel load is started in the lower floor, and its vertical spread up the exterior side of the exterior wall is measured during a specific time-frame. The test was developed in the early 90’s in reaction to concerns over the rise in the use of foam plastic in exterior walls. By 1998 it had been adopted by NFPA as NFPA 285. Currently the test is referenced in the 2018 International Building Code and has seen no changes since 2012. In the IBC, the test targets the use of foam plastics in buildings regardless of height. NFPA 285 is required if the building is taller than 40 feet and the exterior wall assembly contains combustibles. Also, there are specific requirements regarding the inclusion of a water-resistive barrier.
In the 2019 version of NFPA 285, the scope of the test was increased to include load-bearing exterior walls and expanded beyond buildings with combustible materials. The test is now applicable to all “Types of Construction” as defined by the IBC. Based on the materials used in a specific building and their ability to resist fire, the code will classify the building into one of five categories, Type I through Type V. New in 2019 is if the exterior wall consists of panels, then there must be two panel joints in the test with their locations specified. The window detailing is now part of the test. The test standard dictates specific window opening construction. The intent is to expand the range of the test. If that detail is not used, then the test performance is limited to what was tested.
Incorporating WRBs has become an integral part of exterior wall design. They are required by code and also impact NFPA 285 testing. The 2012 IBC stipulated that any building over 40 feet in height and of Types I through IV that use a combustible WRB must be NFPA 285 tested. However, the 2015 IBC listed two exceptions in which the NFPA 285 test would not be required.
Since its inception, NFPA 285 has been considered a system or assembly test, meaning there was no allowance for material substitution. If any material deviated from what was tested, then the test was not acceptable. That created a challenge for WRBs. Many times, the only variation from one assembly to the next was the use of a different WRB material. Future consideration within the standard is the inclusion of guidelines to allow for engineering judgments. The corollary to this is what is currently accepted for fire resistive tests. Where the proposed fire-resistive assembly for a project doesn’t exactly meet what was tested, an engineering judgment may be acceptable to the authority having jurisdiction.
This version of NFPA 285 is slated to be referenced in the 2021 version of the IBC. The most current IBC is the 2018, and it has only been adopted by 18 states and Puerto Rico. It can be presumed that the new version will not have an immediate impact because of the time lag between when a new code version is published to when it is adopted.
There are several ways that the 2019 NFPA 285 will impact the contractor. The standard will be applicable to more buildings by including those with load-bearing exterior walls, and all building types. Contractors may be asked to expand test verification of systems on more projects. One question that remains to be answered is if panelized construction will have to be tested specifically to determine the effect of panel joints. It could be interpreted that a panelized cold-formed steel framed curtain wall system with panel joints may have to be evaluated by a test. The ability to use engineering judgments will increase the value of the contractor by offering cost effective alternatives available without having to run a fire test.
Robert Grupe is AWCI’s director of technical services. Send your questions to grupe@awci.org, or call him directly at (703) 538.1611.
