As the government and general public focus on energy-efficient building envelopes, the expectation for superior building performance has heightened. Energy regulations and demand for better building envelope performance has resulted in an increased use of polystyrene, polyisocyanurate, and polyurethane foam plastics. Demand for these materials has elevated the importance of complying with NFPA 285—a standard fire test method for evaluating fire propagation characteristics of exterior wall assemblies containing combustible components.
The International Building Code generally requires exterior walls in Types I and II, III and IV construction to be built of noncombustible materials but permits combustible insulation and wall coverings in some cases based on NFPA 285 testing. NFPA 285 determines fire propagation characteristics for post-flashover fires of interior origin, and requires visual observations of flame propagation and assessment of temperature data during the test.
The purpose of NFPA 285 is to evaluate the ability of the wall assembly to resist flame propagation under standardized fire conditions for the following:
- Vertically over the exterior face of the wall assembly.
- Vertically within the combustible components from one story to the next.
- Vertically from one story to the next.
- Laterally from the compartment of fire origin to adjacent compartments or spaces.
Testing for Errors
The NFPA 285 testing apparatus is a two-story unit consisting of two 7-foot rooms divided by an 8-inch concrete slab wall with a bottom floor and top ceiling made of 6-inch concrete slabs. The structure is a minimum of 16 feet, 10 inches tall and 13 feet, 4 inches wide. To ensure the test is conducted in conditions as close to actual field installations as possible, the test wall assembly is built per the manufacturer’s instructions and must contain vertical or horizontal joints when applicable. A 30-inch by 78-inch window opening is located on the ground floor unit, 30 inches from the floor. This is where the window gas burner is placed during testing. An additional gas burner is placed inside the room, and used to start the fire on the ground floor. The window gas burner is ignited five minutes into the test.
While the test seems simple in design, it requires skilled professionals with a deep understanding on how to set up, calibrate and utilize the equipment. After the 30-minute test is completed, the flame propagation of the wall assembly and temperature is analyzed.
Externally, the flame propagation can be no farther than 10 feet vertically above the window opening and no greater than 5 feet horizontally from wall centerline. Thermocouple measurements inside the wall assembly determine whether the temperature exceeds the 1,000 degrees Fahrenheit limit during the test. There can be no flaming in the second story room and the temperature cannot exceed 500 degrees F above the ambient temperature. The temperature of the combustible components within the wall assembly cannot exceed either 750 or 1,000 degrees F depending on the thickness of the combustible component.
Because of the size of the assembly and multiple pass/fail criterions, this is a large, complex test that is onerous on manufacturers especially when considering the costs involved in running a test program. Manufacturers typically don’t have only one type of wall assembly; rather they have multiple configurations using various types of components depending on the requirement of the project. It would be impossible for manufacturers to test every configuration of the wall assemblies that will be built in the field, let alone being very cost prohibitive. This is where third party accredited certification agencies can provide value through a certification program.
A test report simply states that the wall assembly that was submitted by the manufacturer, as assembled, met the requirements of the test standard. A certified assembly, recognized in a listing program under an accredited certification program would state that every wall assembly built per the listing report complies with the requirements of the test standard. This is accomplished by the certification agency obtaining full traceability of the test samples, developing a quality control program with the manufacturer, and ensuring on-going compliance through unannounced inspections at the manufacturing facility.
Key Benefits of Certification
- Regulatory Requirement—In some instances, code or local jurisdiction makes certification a requirement, often on those products whose assembly cannot be validated in the field.
- Product Modification—If a certified product is modified, it may not have to undergo full-scale re-testing and may only require certain components retested or the product formulation re-evaluated, which can result in significant cost savings.
- Product Differentiation—Certification can also give a manufacturer’s product the advantage when it is compared side-by-side with similar products. A certified product stands out for its quality, acceptance and overall perception.
- Risk Mitigation—When a product is certified, it is required for follow up services throughout its lifespan by the certifying third-party agency. This helps mitigate any problems with the quality of the product.
- AHJ Assistance—Product certification can also streamline the review process for AHJ’s—a certification mark indicates a product has been tested to appropriate standards by a known independent third-party certification agency, further ensuring validity.
However, the greatest benefit for manufacturers that need to comply with test standards such as NFPA 285, is in the up-front work done in a certification program through a test plan. Typically, an engineer will work with the manufacturer to understand the type of wall assemblies, the various configurations and components that will be utilized by them in the field. The engineer takes this information and develops a “worst-case” test scenario using engineering principles and small scale test data to determine the assemblies that need to be tested to grant a listing report for all the configurations and components desired by the manufacturer. This up-front work ensures that all of the options have been considered, a “worst-case” test program has been established, and the listing report will cover all of the configurations. All of this can be achieved without testing every configuration and is presented in a publicly viewable listing report.
The benefits of a listing report over a test report are that no proprietary information is shared with the public, there is no shelf-life to the listing report as long as the manufacturer remains in the certification program and up-to-date, and specifiers, architects and AHJs have more trust in an independent accredited certification agency presenting the information through an online certification directory. All of the information needed to confirm that the wall assembly being installed in the field is representative of what was tested is easily accessible in the listing report and the design listing; the alternative is a 20-page test report that the reader has to review and understand.
There are three certification agencies in the U.S. that are currently accredited to test and certify assemblies to the NFPA 285 fire test—Intertek (with two testing facilities in San Antonio, Texas and York, Pa., Southwest Research Institute in San Antonio, Texas and Underwriters Laboratories in Northbrook, Ill. The standard time frame to complete an NFPA 285 certification process is about three months.
The NFPA 285 test is paramount to meeting minimum fire performance requirements for building envelope construction as mandated by the building and fire codes. Fire performance testing and certification are key to providing AHJs, architects and specifiers with valid documentation of performance. NFPA 285 is playing an increasing role in assessing fire performance as more combustible materials are used on Types I, II, III and IV buildings.