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How to Create a Fire Resistant Building Envelope

We all understand the importance of using fire protection systems in our home and offices. However, unfortunately, there has not been much focus on fire resistant construction for the building façade. Things get even more complicated because we often ignore the exterior building components that have a role in prevention of loss caused by fire and natural hazards.

In any commercial and industrial building, the building envelope is critical to restricting the spread of fire, minimizing property damage caused by fire, and mitigating any interruption caused to business. In this regards, it is extremely important to adhere to the loss prevention guidelines derived from scientific studies and make use of products that have been rigorously tested and certified. This approach will not only help us limit the loss caused by fire, but also prevent them from occurring.

There is no denying the fact that the majority of losses resulting from man-made and natural elements can be prevented. It is possible to build well-protected facilities with much lower property loss potential because of fire by using performance-tested products and proven installation and maintenance guidelines.

Building Envelope Engineering: The critical components of a building envelope include walls, flashing systems, fenestrations, roof mounted systems, roofing systems, etc. From the perspective of loss prevention, the building envelope functions as a protective outer shell to protect the interior from fire and natural hazards. The basic components of a building envelope include

  • Roofing Assemblies: Fastening systems, insulation, decking, flashing, and membrane
  • Exterior Wall Assemblies: Cavity walls, solid walls, etc.
  • Fenestrations: Doors, windows, shutters, skylights, etc.
  • Roof-mounted systems: Photovoltaic panels, cooling towers, etc.

Roofing Assemblies: Roofing assemblies are extremely important components for a building envelope because they can create the first line of defence against a fire hazard.  Ideally, the roofing assemblies must be able to protect the interior of the building from temperature extremes, high winds, snow, hail, rain, etc. For a fire resistant building envelope, the roofing assemblies should be able to limit the spread of fire from internal as well as external risks. Some common external risks include rooftop hot work, flying embers from buildings in close vicinity, etc. On the other hand, internal risk may come in the form of failure of electrical or mechanical equipment, and presence of combustible materials.

To ensure the highest level of fire protection, it is important for the builders to rely only on roof assemblies tested and certified not just individually, but as complete systems. Assembly testing should comprise of fire testing of the deck, both below and above it.

Exterior Wall Assemblies: One more major component of a building envelope is its exterior wall assembly. It is important to make sure that the wall assemblies are capable of limiting fire spread from potential external risks such as fire from buildings nearby, ignition sources such as hot work, grinding sparks and electrical shorts, as well as internal fire risks.

Previously, it was necessary to conduct full-scale fire testing for walls and ceiling panels. However, this expensive and time-consuming process has now been replaced by intermediate- and small-scale testing. For example, the small-scale Fire Propagation Apparatus and intermediate-scale tests such as the Room Fire Test and Parallel Panel Test have now almost replaced the full-scale 25 ft. and 50 ft. corner fire tests.

Roof-Mounted Systems: To benefit from the elevated location and save footprint space, photovoltaic systems and cooling towers are often mounted on roofs. Unfortunately, however, this contributes to a higher fire risk.

There is a common perception that cooling towards are safe from fire as it contains flowing water.  However, cooling towards are susceptible to fire because they contain electrical equipment, dry areas, and combustible materials such as ABS, FRP, and PVC. During regular maintenance, fire risks are increased as water flow may be turned off. This may trigger fire because of electrical arcing, hot work, or human errors.  In addition to testing and certifying as complete systems, cooling towers must be evaluated for debris impact, fire risk, seismic loads, as well as cyclic and static air pressures.

In order to achieve energy efficiency and adhere to the latest sustainability regulations, many building envelopes now come with Photovoltaic (PV) systems. However, these specialised installations can adversely affect any roof assembly’s fire performance. Both rigid as well as flexible PVC modules must be evaluated thoroughly for risk mitigation.

Fenestrations: Fenestrations are often referred to as the weakest link of a building envelope and demand special attention during the designing phase to ensure resistance to fire. For example, plastic made skylights pose a fire risk from external as well as internal sources. Fire tests must be conducted to evaluate the skylight’s ability to limit the flame from spreading. This test can also help determine the propensity of the sample to melt and drip. This melting and dripping has a significant negative impact on the performance of sprinklers placed just below the skylights.

Hope all of you enjoyed going through this article. At CGS Facade Group, we provide end to end solution for all your requirements related to building facades. Please fix an appointment with our expert to discuss your next project.