NFPA 285: A Fire Safety Standard for Wall Assemblies in the U.S.
Ensuring the safety and performance of building materials
25 April 2023
Building and construction materials and projects need to withstand a number of elements to ensure the safety of occupants, neighboring structures, and the surrounding area. Building codes and standards have been developed to address potential damage caused hurricanes, tornadoes, fires, and more.
In this blog we're going to focus on fire safety. Fire and flammability standards and test methods for the building and construction industry are developed by the National Fire Protection Association (NFPA), a global nonprofit organization that is devoted to eliminating death, injury, property and economic loss due to fire, electrical and related hazards. Today we are going to look specifically at the NFPA 285 Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components.
Purpose of NFPA 285
The purpose of NFPA 285 is to provide a standardized fire test procedure for evaluating the suitability of exterior wall assemblies that are constructed using combustible materials or that incorporate combustible components for installation on buildings. We test to this standard using a specially constructed NFPA 285 apparatus with specific requirements for the test specimen and a detailed test procedure.
2023 Updates to NFPA 285
The 2023 version of NFPA 285 was updated to reflect some necessary administrative changes, as well as the addition of an annex that is not mandatory, but was developed to provide additional guidelines around the extension of compliant test results.
The changes to the mandatory requirements of the standard include:
- The statement that addresses components in the Scope was removed in order to clarify that the standard addresses the curtain wall assemblies, and not the individual components of the assemblies
- In Chapter 2 the title, year, and/or editions were updated on various referenced standards.
- In Chapter 4 clauses related to calibration procedures were moved to Chapter 7, which addresses calibration
- Several sections were added to Chapter 5 to reflect technical changes and additions with regard to sealing the test specimen
- Also in Chapter 5, a clause was added to recognize that that not all walls have steel or wood studs
- In Chapter 10 an editorial correction was made
In addition to the changes to the mandatory requirements, Annex B – Guide for Extensions of Results from Assemblies that Meet NFPA 285 Test Requirements was added. This is just for informational purposes and is not required as part of the standard.
The purpose of Annex B is to provide guidelines for qualified engineers, design professionals, or individual(s) to follow when performing a design for or making an engineering analysis/judgement on NFPA 285-based wall assemblies. It is also meant to provide guidance to help determine whether a wall assembly made up of different materials or construction than a successful NFPA 285-tested assembly will or will not maintain the appropriate fire performance requirements. It is based on engineering principles and testing experience with regard to the extension of test data based on certain considerations. The extension of test data/results in this Annex is based on the fire performance of wall assemblies that meet the acceptance criteria of Chapter 10 of the Standard.
These analyses/judgments can be used for approval when an alternative design, material, or method of construction is proposed for use in a previously successful NFPA 285-tested wall assembly. To apply most of the principles described in Annex B, reference to the test report for NFPA 285-tested wall assemblies will likely be necessary.
The extension of NFPA test results is valid only for changes to the tested specimen that fall within normal and reasonable limits of standard construction practices. Analyses or judgments are only valid if the identified changes are the only changes to the construction or properties of the components. Multiple changes can have a different cumulative effect than that of individual changes applied separately. Annex B recognizes that it is not possible to analyze every configuration or every potential change to a tested wall assembly, and it provides the best information to date. When an engineering/judgement analysis does not support a change, an NFPA test should be conducted. Finally, this annex is only applicable for testing wall assemblies for compliance with NFPA 285. This annex cannot be used for the evaluation of wall assemblies or other materials based on other standards.
For more detailed information on the 2023 updates to NFPA 295, watch our on-demand webinar.