The sheer scope and intensity of the wildfires in Los Angeles in January 2025 has fire experts surveying the damage and looking for clues as to why some residential and commercial structures survived while others burned.

The wildfires, which caused 29 fatalities, destroyed more than 16,000 residential and commercial structures and burned more than 33,000 acres, are considered one of the costliest disasters in U.S. history.

“A new report from the UCLA Anderson Forecast suggests that the two largest wildfires that recently ravaged L.A. County — the Palisades and Eaton fires — may have caused total property and capital losses ranging between $95 and $164 billion, with insured losses estimated at $75 billion,” said a UCLA newsroom release. ”Local businesses and employees in the affected areas could face a total wage loss of $297 million.”

The role of insulated metal panels (IMPs) could offer clues as to how commercial and industrial buildings can help create a fire defense in the future.

Fire Forensic Teams Look for Clues in the Ashes

While the embers were still smoldering from the fires, teams from the Insurance Institute for Business & Home Safety, a non-profit research group that studies how buildings burn, were on the ground.

“Within that wreckage, some homes are still standing, seemingly untouched. It’s a phenomenon that’s been seen in other high-intensity fires, something that can feel like a stroke of luck,” reported NPR. ”Sometimes, the houses survived because the winds could have shifted at just the right moment. But more often, fire experts are finding those homeowners took key precautions that likely saved their houses from burning.”

On a short list of precautions (including clearing vegetation and space between buildings) that spared structures are the use of fire-resistant materials in construction, especially metal roofing.

IMPs Offer Commercial and Industrial Buildings Fire Resistance

Owners of commercial and industrial buildings have the option of IMPs, which are engineered to meet rigorous fire safety standards.

Green Span Profiles American-made roof and wall IMPs, for example, pass fire resistance testing for several standards including FM 4880 standards that certify the materials as Class 1 Fire Rated (the equivalent of Class A fire-resistant rating).

IMPs, as defined by the Metal Construction Association (MCA) , are lightweight composite exterior wall and roof panels with two layers of coated thin sheet metal (typically steel or aluminum) wrapped around a rigid foam core to form a stiff composite.

The plastic foam core gives these panels not only superior insulating properties, but also fire-resistant properties.

“The use of Insulated Metal Panels containing foam plastic insulating materials, when they comply with the appropriate fire test requirements for both the components individually and the assembly, for example as used in the U.S., have been shown to exhibit excellent fire performance and have not been involved in any significant number (if any) of tragic fires,” wrote Marcelo Hirschler, GBH International, a fire testing contractor, in an MCA white paper on the Fire Safety of Insulated Metal Wall Panels.

While traditional IMPs offer good fire resistance, commercial and industrial buildings can add an extra layer of protection by using IMPs with mineral wool in the core, which is considered non-flammable and non-combustible.

Green Span Profiles Insulrock fire-rated panels, for example, use ROXUL ConRock L structural mineral wood in the core which is fire-rated from 1 to 3 hours depending on panel thickness.

What Makes IMPs Fire-Resistant Building Materials?

IMPs, such as those manufactured by Green Span Profiles, integrate three layers of fire defense:

• Non-combustible steel facings that resist ignition and flame spread
• A polyisocyanurate insulating foam core with inherent fire-retardant properties
• Interlocking seams that eliminate gaps where flames and embers could penetrate

These panels are engineered to perform under extreme conditions, earning certifications through rigorous testing:

Closer Look at IMPs Fire Testing Standards

IMPs undergo rigorous fire safety testing to ensure they meet stringent building code requirements. Here’s how IMPs perform under key fire safety tests:

ASTM E84: Surface Burning Characteristics

This test, also known as the “tunnel test,” evaluates the surface burning characteristics of building materials:

• Flame Spread Index: IMPs typically achieve a rating of 25 or less
• Smoke Developed Index: IMPs usually score 450 or less

These results indicate excellent resistance to surface flame spread and smoke development.

NFPA 285: Multi-Story Fire Test

This critical test evaluates the fire propagation characteristics of exterior non-load-bearing wall assemblies:

• Assesses vertical and lateral flame spread on the exterior wall surface
• Measures fire propagation within the wall assembly
• IMPs must prevent flames from extending more than 10 feet vertically from the opening
• Exterior temperatures must not exceed 1000°F at specified points
• Interior temperatures must not rise more than 500°F in the second-story room

Many IMP manufacturers have successfully passed NFPA 285 tests in various wall configurations, demonstrating their ability to contain fire spread effectively.

FM 4880: Class 1 Fire Rating

This Factory Mutual test evaluates the fire performance of insulating materials used on indoor walls and ceilings:

• IMPs are tested for flammability and fire propagation
• Successful performance can result in a Class 1 rating
• Some IMP assemblies achieve unlimited height classifications under this standard

Meeting Stricter Codes and Rebuilding Smarter

As wildfires intensify, building codes are evolving rapidly to prioritize fire-resistant materials and designs.

Insulated metal panels (IMPs) from Green Span Profiles are at the forefront of this shift, offering solutions that meet — and often exceed — 2025’s stringent wildfire-resilience standards.

New regulations focus on three critical areas:

• Wildland-Urban Interface (WUI) Codes:
  o   Mandate non-combustible exteriors (e.g., steel, fiber cement) and ember-resistant designs
  o   Require Class A-rated roofing (ASTM E108/UL 790) and fire-resistant underlayment to block ember penetration
  o   Enforce Zone 0 compliance: A 5-foot ember-resistant buffer around structures
  
  
• Chapter 7A (California Building Code): 
  o   Prohibits flammable siding in high-risk zones, favoring IMPs with non-combustible steel facings
  o   Requires dual-pane tempered-glass windows and fire-rated vents to prevent ember intrusion
  
  
• ANSI/UL 263 (ASTM E119) Standards
  o   IMPs with mineral wool cores achieve 1- to 3-hour fire-resistance ratings, maintaining structural integrity at 1,800°F

IMPs can help rebuild smarter for commercial and industrial building owners by offering:

• Faster compliance: Prefabricated IMP systems streamline permitting in code-strict states like California where WUI is accelerating.
• Insurance Incentives:Buildings using IMPs can reap insurance incentives as some insurers offer discounts for metal roofs.
• Faster Rebuild Times:IMPs’ easy installation saves on time and resources.

Green Span Profiles IMPs meet new, more stringent requirements for fire protection and offer an excellent solution for buildings in high-risk zones. Contact Green Span Profiles today to learn more about how you can protect your investment with fire-resistant building materials like IMPs.