Seconds Save Lives: How Passive Fire Protection Buys Critical Evacuation Time

Across North America and Europe, this summer has brought record-breaking heatwaves and unusually dry weather. According to data from the National Interagency Fire Center (NIFC), wildfires have burned more than 6.3 million acres in the United States, year-to-date—a notable increase compared to the 3.6 million acres burned during the same period last year. With hot, dry conditions stretching across the continent, property owners, architects and builders are looking at how materials perform amid extreme heat.

When a wildfire approaches a populated area, airborne embers and radiant heat pose an immediate threat to buildings. While active fire systems like sprinklers rely on water pressure and electricity to put out flames, passive fire protection works silently. It uses naturally fire-resistant building materials to create a thermal barrier that slows the spread of flames, keeps toxic smoke contained and helps prevent structural collapse.

In an emergency, passive fire protection isn't meant to make a building invincible. Its primary job is to protect human life by buying time—giving occupants the critical minutes they need to escape safely, while affording first responders time to arrive.

How Material Science and Rigorous Testing Guard the Building Envelope

Johns Manville (JM) designs building insulation and commercial roofing systems to help structures withstand extreme heat and flames:  

• Continuous Mineral Wool Wall Shield (CladStone® Water & Fire Block): Made from natural volcanic rock, mineral wool insulation is inherently noncombustible. It can withstand temperatures over 2,000°F (1,093°C) without melting. Installed continuously along exterior walls, it helps stop fire from climbing up the outside of a building while allowing trapped moisture to drain safely. 
• Charring Roof Panels (ENRGY 3® Polyiso): Commercial roofs are especially vulnerable to windblown embers. JM polyiso roof insulation boards are made of a thermo-set foam material that chars into a protective layer when exposed to intense heat, rather than melting or dripping. When combined with fire-rated cover boards and single-ply membranes, these roof systems can achieve UL Class A fire ratings—the highest standard for resisting fire spread from airborne embers. 
• Microlite® Duct Wrap Insulation (Microlite® FSK Duct Wrap): This HVAC insulation solution helps improve energy efficiency every day of the year while providing an additional thermal barrier around ductwork in the most critical situations in the event of a fire by supporting the integrity of the building envelope. It helps slow heat transfer and limit pathways for heat and smoke movement, contributing to a building's overall passive fire protection strategy. Microlite® also meets the Surface Burning Characteristics and Limited Combustibility requirements of recognized standards, including ASTM E84, UL 723, NFPA 90A and 90B, UL Guide No. 40 U8.3 Card R3711, and CAN/ULC S102, helping support safer, more resilient building designs. 
• Underground Water Line Protection (Evalith® Nonwovens): Protection doesn't stop at the roofline. JM manufactures high performing Evalith® glass nonwovens that are embedded within the thermoplastic inner coating of the GRP structure in underground pipe liners as rehabilitation solutions. These liners reinforce municipal water pipes without digging up roads, helping preserve local water supplies during regional emergencies.
• Rigorous Fire Testing: To ensure these building systems hold up under real-world stress, JM engineers conduct rigorous internal fire testing at our technical facilities. R&D teams evaluate JM products directly alongside other materials, using direct flame torches and radiant heat sources to measure flame spread, smoke generation and structural breakdown. By testing materials under extreme thermal conditions, JM validates that our products deliver dependable fire resistance when it matters most. Learn more about our fire testing and our testing process by watching our Built to Protect fire videos.

By focusing on rigorous safety testing, innovation and honest performance, JM delivers on its Perform and Protect values to create solutions that help protect people, support emergency crews and build stronger communities.