Photograph by Daniel Lunghi
The fire performance of aluminum composite material (ACM) systems on the facade of a building is extremely critical now; recent global fire events have heightened the awareness of ACM creating concerns regarding occupant safety, as well as property loss. An ACM system’s ability to mitigate the risk caused by fire is increasingly important as innovative design-oriented goals of sustainability and energy efficiency requirements have emerged. The building envelope is now challenged to respond to the movement of heat, air, and water over the life of the building. As a result, ACM cladding systems must allow for this flexibility as well, adding to the complexity of the fire performance in the exterior wall assembly.
Still, not all ACM is manufactured with the option of a fire-resistant core. And in many countries these restrictions are relatively new and do not apply to previously constructed buildings, which can result in catastrophic fires like those recently seen in Dubai. These fire events in Dubai have certainly raised many questions regarding the use of specific cladding materials for exterior applications.
It is not always clear what cladding material was used, whether the materials actually met the local code requirements, and whether the local codes were adequate or even enforced. Dubai has probably the highest concentration of ACM use in the world in approximately a 200 square mile area. All of this was essentially built and installed in “The New Dubai” during the past 20 years.
However, stringent regulations regarding fire performance were only recently tightened in 2012 and then again in 2013. The newly established codes are certainly robust, so technically, there shouldn’t be any inferior ACM being installed in Dubai now. The daunting issue, however, is the legacy: there were a significant number of towers built prior to the existing controls and recommendations. Many may not comply because they were built before the new rules were introduced; and it is likely ACM without a fire-retardant core was used, as seen in several of the recent fire events in Dubai.
The ACM material is burning so profusely in Dubai because the building envelope contains some very combustible materials. Again, any construction with an ACM exterior cladding system in Dubai prior to 2012 is assumed to have a polyethylene core. The test requirements, installation practices, code requirements, and the expected product performance certainly indicate the level of risk that was deemed acceptable at that time.
As an example, the Address Hotel, built before 2012, had a specification that stipulated a FR core material, but in this case, FR was interpreted as fire-resistant. This led to the assumption that ASTM E119, the Standard Test Method for Fire Tests of Building Construction and Materials, was an acceptable compliance test standard. However, the intent of ASTM E-119 is to evaluate, in terms of resistance time, the ability for fire containment; how well a building system prevents a fire from spreading to an adjacent space while maintaining their structural integrity.
ACM with a PE core as the outer most layer of an ASTM E119 tested wall assembly can certainly meet the requirements of an hourly rating. However, ASTM E119 does not measure flammability; the fire propagation of materials on exterior wall assemblies is actually assessed through the Multi-Story Fire Propagation Wall Assembly Test, NFPA 285. Consequently, many of the wall assemblies utilizing ACM in Dubai is below specification, below code, or the code was not adequate in addressing the exterior cladding flame spread issue.
It is critical to note that Alucobond is not concerned about these types of fire events occurring in the United States. Precautionary measures have been implemented over the years for ACM as well as the entire wall assembly. Building codes in the United States that address material and fire performance criteria have truly become sophisticated during the past decades.
Photograph © Kate Hensley, Suffolk Construction
Fire test standards for building materials and assemblies in the US now include small bench-scale, medium scale, and large-scale testing. These standards measure different parameters, such as surface-burning capabilities, fire containment, and flame propagation. However, unlike several other areas in the world, large scale wall fire testing has been required by the building codes in the United States for more than 35 years now and Alucobond has been on the forefront in the development every step of the way.
The required large-scale fire test standard in the US is the NFPA 285. This standard involves a two-story wall assembly measuring approximately 13 feet wide by 18 feet high and is exposed to a flame source equivalent to the intensity to a fire breaking out of a window of a fully involved room. This is a very stringent test and is also being adopted by many jurisdictions around the world. As a result, Alucobond has been very diligent to test, successfully, many different wall assembly configurations to meet the needs of the design community. Architects, building owners, and contractors can now demand only those products that have shown conformance to all the material and assembly-test criteria as required by the building code and Alucobond can meet these expectations.
Alucobond does still manufacture aluminum composite material with a polyethylene core. The market still has a place for Alucobond with a PE core, and when applied correctly, performs well. Low rise buildings or car dealerships are considered low risk and are great examples of structures that do not necessarily need the stringent fire performance requirements. While the appearance may be equal in the wall assembly, there can be quite a difference in the performance of an ACM when exposed in a fire situation. Only products that have shown conformance to the local code should be allowed for use in a high-rise and high-risk construction. While the fire code does not actually set a standard level of performance, here at Alucobond, we recognize, after many years of manufacturing ACM, the right product must be used in the right application for a building to perform safely.
Photograph © John Swain
Transparency within the manufacturing team is paramount to manage selling the right product for the right application. We understand the life safety issues that are at stake and this inspires us to look at each project critically. The key element to our success though, has been through education. We have been diligently working with the building industry and design community, helping them understand the correct applications of Alucobond, as well as understanding the building code and relevant fire test standards. We emphasize the difference between test standards and we also differentiate between important concepts such as fire rating, fire resistant and fire retardant.
Photograph © Falk von Tettenborn Architects
Alucobond has also partnered with several industry professionals, including a fire protection engineer, an architect, and a testing facility to form a discussion panel. This team has educated several groups on the challenges of designing to comply with the building code as well as understanding the NFPA 285 fire performance test standard. But these panel discussions have also helped Alucobond understand the needs of the architectural community, the fire protection engineers, and the testing facilities. It has prompted us to continue our own education regarding fire protection engineering and building science to better understand the dynamics of all the components of the building envelope. Also, active involvement in the aluminum composite material industry organization, MCA, as well as NFPA, and the ASTM committee on Fire Standards keeps Alucobond on the forefront of testing and code development.