Does My Wall Assembly Have to Comply With NF PA 285? Heather Pasc hal , Ass ociate AIA, LEED AP Henry Company 999 North Sepulveda Blvd., Suite 800, El Segundo, CA 90245 Phone: 972-510-8956 • E-mail: hpaschal@henry.com S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3 P as c h a l • 8 5 8 6 • P as c h a l S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3 ABSTR ACT Adoption of 2012 International Building Code (IBC) and 2012 International Energy Conservation Code (IECC) may directly affect the prerequisite that exterior wall assemblies in multistory buildings are obligated to pass NFPA 285. Projected continuous insulation (CI) requirements have dramatically increased demand for NFPA 285-compliant wall assemblies. Code requirements continue to evolve, making “typical” wall assemblies obsolete and resulting in code-mandated modification of master specifications, details, and construction practices. These changes will alter the understanding of building envelope systems, leaving design and construction professionals asking: Does my wall assembly have to comply with NFPA 285? The answer is: It depends. SPEAKER Heather Paschal, Associate AIA , LEED AP — Henry Company Heather Paschal is a building science specialist for the South Central U.S. in Henry Company’s Building Envelope Systems division. Heather’s work focuses on code verification and analyzing building systems associated with air barriers, spray foam, waterproofing, and vegetative roofing. Her experience includes architectural project management, tapered insulation design and consulting, and submittal management for waterproofing and roofing companies. She has a degree in architecture and a LEED AP certificate, and is a member of AIA and RCI. S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3 P as c h a l • 8 7 Interests in the National Fire Protection Agency’s NFPA 285 have amplified due to the 2012 International Energy Conservation Code (IECC) requiring continuous insulation (CI) in all climate zones and increase of rigid or spray foam in exterior wall assemblies to meet the thermal prerequisite. NFPA 285 is a wall assembly fire test (Figure 1) originally required by the building code when the use of foam plastics—such as exterior insulation and finish systems (EIFS)—became popular. Foam plastic insulation creates a highly efficient building envelope but can be extremely flammable. Addition of foam insulation in an exterior wall can increase the flame spread and heat generated, thereby escalating fires and triggering migration vertically or laterally at the wall cavity. The purpose of requiring NFPA 285 compliance is to regulate combustible components in exterior wall assemblies of multistory buildings and limit fire spread to other floors or adjacent areas. Therefore, use of combustible components, such as foam plastic insulation, to meet the demand for energy-efficient buildings will make current practices obsolete. To understand if a wall assembly must comply with NFPA 285, a design and construction professional must understand building construction types, how the test is conducted, which components will trigger compliance, and the anticipated changes in building codes. Intent of NFPA 285 The purpose of the NFPA 285 fire test method is to simulate vertical and lateral heat and flame spread when a fire originates from the interior of a structure. This test evaluates the fire propagation characteristics of an exterior wall as an assembly, rather than individual components, where combustible materials are anticipated in noncombustible construction types. Fire activating on the interior of a multistory building may extend to adjacent floors or areas. This is especially true when exterior walls are no-load-bearing assemblies, because they allow for wall cavity air movement in multistory buildings. Addition of combustible components on a no-load-bearing multistory structure increases the exterior wall’s flammability. Fire risk in these types of assemblies may result in far more aggressive fires and increase occupant risk in adjacent locations. Evaluation of these fire characteristics is to protect the safety of occupants and decrease the possibility of fire engulfing adjacent areas at undetermined rates. Therefore, the four main focuses of the test are to measure an exterior wall assembly’s resistance to the following: • Flame propagation over the exterior face of the wall assembly • Vertical flame propagation within the combustible components from one story to the next • Vertical flame propagation over the interior surface of the wall assembly from one story to the next • Lateral flame propagation from the location of fire origin to adjacent compartments or spaces A Brief History EIFS—also known as synthetic stucco— became popular in the U.S. around the late 1970s as escalating energy costs and high Does My Wall Assembly Have to Comply With NF PA 285? Figure 1 – Example of NFPA 285 burn. Figure 2 – IBC Reference Table 601 – Fire resistance rating requirements for building elements. oil prices increased demand for energyefficient buildings. EIFS is an exterior finish intended as an insulated waterproofing veneer. This system provides a lightweight insulated wall cladding by adhering rigid insulation board onto a substrate and applying a synthetic coating for weather protection. Foam plastic insulation is manufactured with polyurethane and, therefore, is flammable. Increased use of combustible components (including EIFS) associated with noncombustible wall assemblies in building types I, II, III, and IV (Figure 2) sparked alarm amongst design and construction professionals. Therefore, in 1980, the Society of the Plastics Industry (SPI) designed NFPA 251, Standard Methods of Tests of Fire Resistance of Building Construction and Materials. NFPA 251 is an outdoor, fullscale fire test used to analyze the increased fire risk of exterior wall assemblies containing combustible components such as plastic foam insulation. The test was successful in indicting flame spread and heat development linked to the addition of combustible products in a multistory exterior wall apparatus and was added to the Uniform Building Code (UBC) in 1988. Due to the size and nature of NFPA 251, the test was quite laborious and costly to conduct. Therefore, continued efforts of SPI eventually led to a smaller-scale version of the original fire test program. This test is known as NFPA 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible 8 8 • P as c h a l S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3 Figure 3 – Plan view of testing apparatus (not to scale). Figure 5 – Plan view of thermocouple locations on testing apparatus (not to scale). Figure 6 – Exterior elevation of thermocouple locations on testing apparatus (not to scale). Figure 4 – Section of testing apparatus (not to scale). Components Using the Intermediate-Scale, Multi-story Apparatus. NFPA 285 is able to effectively analyze the consequences of combustible components on exterior wall assemblies at a much less aggressive scale than NFPA 251. By reducing the size of the wall apparatus, the test is able to be conducted efficiently indoors and is far less expensive. Ultimately, NFPA 285 was adopted by NFPA in 1998 and recognized as an alternative to NFPA 251. Conducting the NFPA 285 Fire Test An NFPA 285 testing apparatus must be constructed, as prescribed by the standard, with minimum dimensions of 13 x 12 x 18 ft. (Figure 3) and equipped with two gasfired burners. One burner shall be located on the interior of the first story and the second placed at the window rough opening (Figure 4). Initially, a fire is ignited at the interior burner, simulating an interior fire source. The interior fire is maintained, permitting flashover to occur and igniting the second burner located at the replicated window opening. Finally, the tested assembly must stay within the flame spread and temperature test limitations for 30 minutes, or the assessment is considered a failure. A passing result is based upon visual observations and temperatures taken at various thermocouples during the allotted time (Figures 5, 6, 7, and 8). These limitations include the following: Visual observations • Flame propagation shall not extend vertically or horizontally into the wall cavity, igniting the combustible materials, and must stay within prescribed temperature limitations as determined by the wall assembly specimen. • Flames cannot occur beyond the sidewalls of the testing assembly. Flame propagation on exterior face of testing assembly • Temperatures must not exceed 10 percent of the average values associated with Table 7.1.11, NFPA 285 requirements associated with thermocouples 1-7 and calorimeters 2-4. • Temperatures must remain below 1,000°F (538°C) at thermocouple nodes 11 and 14 through 17. • Flames must not extend greater than 10 ft. above window rough opening. • Flames must not extend greater than 5 ft. horizontally from center of window rough opening. Flame propagation at combustible components in wall cavity • A s s e m b l i e s with no cavity air space: Temperatures must remain below 750°F (417°C) at thermocouples 18, 19, 28, and 31 through 40. • Assemblies with cavity air space: Temperatures must remain below 1,000°F (538°C) at thermocouples 18, 19, 28, and 31 through 40 and 750°F (417°C) at thermocouples 55 through 67 and 78 through 80 as applicable. Second Story • Temperatures in the second story of the testing apparatus shall not exceed 550°F (278°C) above the ambient air temperature prior to testing. S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3 P as c h a l • 8 9 Figure 7 – Interior elevation of thermocouple locations on testing apparatus (not to scale). Figure 8 – Temperatures of thermocouples must not exceed 10 percent of the listed values in accordance with Table 7.1.11 of the NFPA 285 testing assembly. • Flames cannot occur in the interior of the second story. Due to the fact that NFPA 285 is an assembly test, results are only valid when the wall components consist of the specific assembly used during testing. Thus, a passing evaluation is no longer valid if any components are modified. For example: A wall assembly consisting of interior gypsum, steel studs, insulation, exterior sheathing, weather barrier, air gap, and exterior cladding (Figure 9) that has a passing result with NFPA 285 will not necessarily pass if the cladding is altered. Understanding program parameters and building components is paramount during design and construction document phases in order to determine the need for NFPA 285 compliance. Furthermore, a wall assembly passing or failing result may be influenced by the detailing of rough openings. There are a number of ways to solve a fenestration detail. Careful consideration for determining rough opening details must extend to all component—including, but not limited to, flashings, insulation, shelf angles, and, of course, the window itself to ensure NFPA 285 compliance without compromising product warranties. This is why referring to manufacturerpublished literature is important when designing an accurate wall assembly. Deviating from a tested window detail will void the validity of a passing NFPA 285 assembly in many cases. For example: A wall assembly that has passed NFPA 285 may require complete separation of the wall cavity from the interior occupied spaces. This can be achieved by extending the window framing from the face of the interior gypsum to the exterior face of the cladding (Figure 10). This approach of detailing a fenestration opening separates combustible materials in the wall cavity from direct contact with an interior fire and limits flame spread dramatically. If the window frame were decreased, leaving the cavity exposed, an interior fire could ignite the combustible materials and allow for the fire to surge uncontrollably into adjacent areas. Engineering Judgments Passing an NFPA 285 assembly test can be laborious and expensive, easily exceeding $30,000 per burn. Therefore, many manufacturers attempt to maximize wall assembly testing by installing one or more combustible products. If a passing test result is achieved, a manufacturer may apply for an alternate wall design, equal to or less flammable than the passing assembly, by means of an engineering judgment. Where deemed appropriate, a licensed consulting engineer specializing in fire code safety may authorize an NFPA 285 passing wall assembly based on substantial submitted data and evaluation. Consequently, it is common practice for manufacturers to offer an array of wall assembly options or “one-offs,” while limiting financial obligations. Only a few years ago, locating a passing NFPA 285 assembly would have been an arduous task. However, due to engineering judgments, manufacturers are now able to offer literature that allows for materials to be selected from a list of preauthorized assemblies. Increased Demand of NFPA 285 Recent attention to NFPA 285 is in part due to 2012 IBC and 2012 IECC code changes. Adoption of the 2012 codes will raise thermal and airtight prerequisites of building enclosures in almost all climate zones (1-8) and construction types I, II, III, IV, and V. New code obligations have extended air barrier requirements to include climate zones 4-8. Also, according to the 2012 IBC, Section 1403.5, wall assemblies containing a combustible air barrier must now comply with NFPA 285, even where no other combustible components are used. In order for an air barrier to be classified as noncombustible according to the IBC, there must be zero flame spread and 9 0 • P as c h a l S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3 Figure 9 – Example wall section tested in accordance to NFPA 285. Modification of any component, including size of cavity air space, may affect wall compliance of NFPA 285. Figure 10 – Refer to manufacturer details for tested fenestration details for NFPA 285 assembly compliance. smoke development when tested to ASTM E84, Surface Burning Characteristics. Class A products exhibit low smoke/flame spread development and, therefore, do not qualify as noncombustible. Furthermore, in most cases, 2012 IECC mandates climate zones 1-8 comply with continuous insulation as defined by table C402.2, opaque thermal envelope requirements. Unfortunately, many insulation and air barriers currently on the market are combustible. Therefore, rising demand for these products will be the most prominent reason why an assembly may have to comply with NFPA 285. As a result, 2012 code has forced design practices to be reevaluated. Code Adoption Most design and construction professionals who are aware of NFPA 285 focus mainly on Chapter 26, “Plastic,” of the IBC. However, as of the 2012 addition of the IBC, the total areas that reference NFPA 285 have expanded to seven sections (Figure 11) and will likely continue to develop. However, as with most regulations, there are exclusions. Exceptions to required compliance with NFPA 285 include load-bearing exterior wall structures; one-story buildings that do not exceed 40 ft., in accordance with Section 1403.5; and, in some cases, buildings that are equipped with an automatic sprinkler as referenced in Section 2603.4.1.4 of the 2012 IBC. NFPA 285 Design Compliance Wall assemblies can rapidly become complicated during the design and construction phases, and interpreting the prerequisite of NFPA 285 compliance is not always easy. Referring to keywords in the NFPA 285 title and description may help decipher if the test is applicable to a wall assembly. NFPA 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components Using the Intermediate- Scale, Multi-Story Apparatus. Therefore, if the building is a singlestory structure with loadbearing exterior walls, and not greater than 40 ft., it can be concluded that no adjacent floors/areas should be in potential danger of flame propagation. Thus, it is likely that the wall assembly does not have to comply with NFPA 285. Also, if a building is type V construction or does not contain combustible materials, it does not have to comply with NFPA 285. As always, interpretation of building code, as well as NFPA 285 conformance, are determined by city and local ordinances; and design and construction professionals should refer to authorizing personnel on a case-by-case basis. Once it has been determined that a wall must comply with NFPA 285, the task of choosing an assembly may seem daunting. Engineering judgments have aided in the swift response to code requirements from product manufacturers, thereby allowing for numerous wall assembly options. To ease the process of designing an NFPA 285-passing wall assembly, many manufacturers have taken the most commonplace wall assembly types and fashioned a number of “plug-in” options (Figure 12). For example, a product manufacturer may have publicly published literature containing a list of products to choose from, including the substrate, air barrier, insulation, cladding, etc. that can be used interchangeably and still comply with NFPA 285. All that a designer must do is choose from the prescribed list of options, and the assembly is deemed NFPA 285 compliant. Also, a request can be made on an individual basis in the event an assembly is needed that is not on the predetermined list of approved assemblies. When multiple manufacturers are included in a specification, the task of coor- S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3 P as c h a l • 9 1 Figure 11 – International Building Code referenced sections pertaining to NFPA 285. Figure 12. dinating a wall assembly while maintaining NFPA 285 compliance can be arduous. Listing multiple manufacturers in a specification offers product options and competitive bidding, is required for publicly funded projects, and is unavoidable in many cases. Providing such selections requires meticulous attention to detail when coordinating drawings and specifications. Traditionally, construction documents divide component descriptions into multiple sections. For instance, an air barrier may be listed in one portion of the project specifications, substrate joint treatment in another, and through-wall flashings in yet another section. Furthermore, the scope of work can be divided between trades upon contract award. For example, a sealant contractor may install the substrate joint treatment, a waterproofing contractor completes the air barrier, and a mason installs the throughwall flashings. Coordination of the assembly from design through installation is important in order to avoid a failing combination of products. Therefore, it is easy to see why communication is paramount amongst all trades responsible for an accurate wall assembly, including architects, engineers, consultants, general contractors, interns, and owners. The Future of NFPA 285 Not everyone is comfortable with the new code requirements. There are a number of anticipated revisions to be included in the 2015 IBC. These projected exclusions will extend exemptions from NFPA 285 compliance to multistory structures where sprinkler systems are installed, where the weather barrier is the only combustible component as defined by Section 1403.5, and to window or door flashings associated with air barrier assemblies. The list of submissions for review grows daily. Implementation of the code will be crucial to designing an appropriate wall assembly Conclusion Advancement in technologies and demands for efficient buildings continue to modify construction practices. Developments in cladding materials, insulation, weather barriers, as well as other products offer positive results such as air sealing and high thermal-resistance values. These improvements have decreased energy consumption and life-cycle costs associated with building construction and operation. Unfortunately, to achieve these types of results, combustible wall components installed in noncombustible construction classifications have become common practice. This makes it difficult to design a modern multistory wall assembly and not be bound by NFPA 285 requirements. Therefore, it is likely the demand for NFPA 285-compliant wall assemblies will continue to increase. Most of the United States is currently observing the 2009 IBC or earlier; however, upon adoption of 2012 code, numerous wall assemblies will be required to pass NFPA 285. The addition of weather barrier and continuous insulation requirements as defined in the IBC and the IECC will only continue to escalate the use of NFPA 285-compliant wall assemblies. Furthermore, future building codes will likely require more stringent guidelines as technology and products continue to be enhanced, thus making presently used specifications and detail drawings obsolete. Building design is ever-changing. Engaging product manufacturers, regularly updating master specifications and details, and understanding the parameters for code requirements are the best ways to protect the occupants of our buildings and to maintain code compliance. Depending on the wall components, one product could inevitably result in a failing assembly. References International Building Code (IBC) International Energy Code Council (IECC) NFPA 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load- Bearing Wall Assemblies Containing Combustible Components Using the Intermediate-Scale, Multistory Apparatus NFPA 251, Standard Methods of Tests of Fire Resistance of Building Construction Materials Details courtesy of Henry Company. 9 2 • P as c h a l S y m p o s i u m o n B u i l d i n g E n v e l o p e T e c h n o l o g y • No v e m be r 2 0 1 3
