The National Fire Protection Association’s NFPA 285 defines a standard test procedure for evaluating the fire resistance of exterior wall assemblies. A new update to the standard, the first since 2012, ushers in important changes that could have far-reaching implications.
The 2018 edition, approved by the International Code Council committee in June, includes new language that specifies where vertical and horizontal seams or joints are placed on the wall assembly to be tested, in relation to the opening on the test specimen. The current (2012) standard does not specify the location of seams or joints, calling only for wall assembly specimens to conform to standard building practices.
The intention of the change is to create a “worst case” scenario for challenging the wall assembly when exposed to flame. Joints may provide a potential area of weakness where heat and flame can infiltrate beneath the cladding material, possibly exposing insulation or other combustible materials.
This change has the potential to invalidate tests conducted according to the 2012 or other prior editions of the NFPA 285 standard. Indeed, in the transcripts of public comments on the proposed change, a manufacturer of metal composite cladding material expressed concern, stating that his company has spent more than $400,000 testing various wall configurations using the current standard, the results of which may no longer be valid. Moreover, he pointed out that customers often request testing the exact wall assembly specified for a particular building project and these assemblies may not conform to the new NFPA 285 standard, depending on where the joints are located. Other manufacturers of exterior wall materials expressed similar concerns.
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With the cost of each fire propagation test, according to the NFPA 285 standard, running into tens of thousands of dollars and up to a week or more of lab time, invalidating the database of existing wall assembly tests would have significant financial impacts for those manufacturers funding the tests. In addition, as one consulting engineer commented, it might take up to a decade to replicate the existing tests according to the new NFPA 285 standard, given the relatively small number of laboratories equipped to conduct such tests.
NFPA 285 is the only test standard that assesses vertical and horizontal flame spread on an exterior wall assembly containing an opening. Since most building exteriors contain windows and other penetrations, this unique feature is critically important for evaluating real-world fire performance. Adding joints and seams into the mix adds another dimension that may, or may not, replicate real-world conditions.
As your NFPA 285 resource, we’ll keep you updated on further developments of this important fire safety standard.
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