Using building materials that are fire-resistant and impact-resistant has always been a priority in construction, but that need was driven home during the devastating wildfires in Hawaii this summer.

“When an inferno tore through Lahaina on the island of Maui, it reduced a historic and charming town to ash and rubble. But the fire left a red-roofed house seemingly untouched by the devastation around it,” NPR reported in August.

While people are calling it the “miracle house”, the owner points to two big factors: luck, and the metal roof installed during recent renovations.

"We removed five layers of asphalt that were on the roof," the homeowner told NPR. When the new metal roof was installed, he added, it included an air pocket to allow heat to dissipate.

As the U.S. grapples with increasingly extreme weather conditions – 2023 has already seen 23 confirmed weather/climate disaster events with losses exceeding $1 billion – the importance of resilient and durable building materials, such as insulated metal panels (IMPs), has never been more evident.

“Since fire safety is a key issue in construction, the presence of metal walls can act as a barrier to fire to help keep an active fire from spreading,” explains a Metal Construction Association white paper.

U.S. building materials undergo a series of tests to assess their ability to resist fire and significant impact.

The Importance of Fire Resistance and Impact Resistance

It’s important to gauge how building materials perform in situations of fire and impacts for the following reasons:

Why Fire Resistance Matters

Statistics: In the U.S., according to the National Fire Protection Association (NFPA), local fire departments responded to 1,353,500 fires in 2021 with these fires causing 3,800 civilian deaths, 14,700 civilian injuries, and $15.9 billion in property damage. A fire occurs in a structure at the rate of one every 65 seconds, and a home fire occurs every 93 seconds.

Definition: Fire-resistant building materials are designed to withstand fire exposure and not contribute to the spread of flames or smoke. They have defined fire resistance ratings, often expressed in hours, indicating how long they can withstand fire without failure.

Why Impact Resistance Matters

Statistics: The U.S. experiences approximately 3,000 hail storms annually, causing billions of dollars in property damage, particularly to roofs and siding.

Definition: Impact-resistant building materials are designed to withstand impacts without significant damage. They protect against hail, windborne debris, and other potential sources of structural damage.

Understanding Fire Resistant Testing

Fire resistance tests typically use a sample of wall material that is 20" x 24", which is exposed to fire and results are recorded.

Products may be exposed to flame individually or with component parts, depending on the test used.

The following tests are used to measure overall fire resistance:

• ASTM E84: Also known as the tunnel test, this test measures the surface burning characteristics of building materials – determining how well they withstand burning. This test assesses both the spread of a flame and how rapidly it consumes a material and what happens to a specific product when it is exposed to flame. It's conducted using a Steiner tunnel and results in a Flame Spread Index and a Smoke Developed Index.
  
  
• NFPA-285: This test evaluates the fire propagation characteristics of exterior non-load-bearing wall assemblies. It assesses the flame spread on the exterior wall's surface. Components are exposed to flame for 30 minutes to determine overall resistance -- individual parts are not tested. Assembly components are assessed together.
  
  
• FM 4880: Factory Mutual (FM) conducts tests for fire-resistant construction materials. FM 4880 evaluates the fire performance of insulating materials used on indoor walls and ceilings. This test checks for flammability. Insulated wall or roof panels are tested with component parts to determine overall fire resistance once installed. 

“Fire testing is an essential step in the development of building materials, ensuring that they are safe and meet regulatory standards. It is also critical to provide necessary data to designers and architects when making decisions about the long-term performance of a building,” explained Advanced Architectural Products.

Understanding Impact Resistant Testing

Impact resistance tests are designed to check the safety and viability of materials used for construction and to ensure that they meet minimum standards for safety.

Each component is tested to ensure it can withstand impact and to determine if the material is suitable for its intended application.

These standards are used by government agencies to create standards for construction in high-risk hurricane locations.

The following tests are used for impact resistance:

• FM 4881 and FM 4771: FM 4881 is a standard that sets performance requirements for exterior wall panels that are exposed to natural hazards like wind, hail, and windborne debris. The standard requires that exterior wall systems meet the requirements for Class 1 Fire Rating (FM 4880). The FM 4771 is the standard that sets performance requirements for exterior roof panels that are exposed to natural hazards like wind, hail, and windborne debris.
  
  
• TAS-201: This Florida Building Code Impact Test is used for hurricane impact-resistant windows and doors. Coastal areas that are highly prone to hurricanes and tropical storms require materials that have been tested using this model for safety.  Windows are assigned a rating that indicates the level of wind that they can resist without breaking during a storm. Different areas require different levels of material performance. Areas like Miami Florida require high levels of wind resistance for windows to prevent home damage and injury.

In an era marked by extreme weather and heightened risks to buildings, the choice of building materials plays a critical role in ensuring safety and resilience.

Fire-resistant and impact-resistant materials can save lives, reduce property damage, and enhance the structural integrity of buildings.

Understanding the tests and standards used to evaluate these attributes is essential for architects, builders, and property owners seeking to protect their properties and communities.