Los Angeles is no stranger to wildfires. In a city where the climate and urban–wildland interface demand extra caution, ensuring that roof coverings meet the highest fire resistance standards is critical. Local building codes require that roof assemblies in high‑fire‑risk areas—especially in Los Angeles—adhere to strict fire performance criteria. Two widely recognized testing standards, ASTM E108 and UL 790, are used to evaluate and certify the fire resistance of roof coverings.
What Are ASTM E108 and UL 790?
Both ASTM E108 and UL 790 are standardized test methods designed to evaluate the performance of roof coverings when exposed to an external fire source. These tests simulate real-world conditions in which flames, burning brands, and radiant heat are present. Key aspects include:
- Spread of Flame Test: This test measures how far and how quickly flames travel across the roof covering.
- Intermittent Flame Test: The roof covering is subjected to cycles of flame exposure to mimic intermittent fire conditions.
- Burning Brand Test: This simulates the impact of flaming embers, determining whether the roof assembly can prevent fire from penetrating beneath the surface.
A roof assembly that passes these tests is typically classified as a Class A roof system—indicating that it is effective against severe fire exposure.
Why This Matters for Los Angeles
Los Angeles’ dense urban environment and frequent exposure to wildfire threats mean that the performance of roof coverings under fire exposure isn’t just an academic concern—it’s a vital public safety issue. Local codes adopted by Los Angeles mandate that new construction or significant roof replacements in high‑risk zones meet a Class A rating. This ensures that:
- Fire Spread Is Minimized: Roof coverings that meet Class A criteria help to prevent flames from quickly spreading across a building.
- Homeowners and Businesses Are Protected: The rigorous standards reduce the chance of roof failure during a wildfire, potentially saving lives and property.
- Insurance and Compliance Are Simplified: Many insurers and regulatory bodies in Los Angeles require a Class A rating, making compliance with ASTM E108 or UL 790 tests an essential part of any roofing project.
Los Angeles Local Code Requirements
In Los Angeles, the local building codes—such as those found in Chapter 9 of the Los Angeles County Building Code and Division 15 of the Los Angeles Municipal Code—specifically require that roof coverings in wildfire-prone areas meet the stringent performance criteria of a Class A roof assembly. These codes reference external fire performance tests (i.e., ASTM E108 or UL 790) to ensure that:
- New Construction: Roof coverings on new buildings must be tested and certified for Class A performance if they are to be installed in areas with a high risk of wildfire.
- Re‑Roofing Projects: If more than 50% of the roof area is replaced within one year—or if the building is located in a designated Very High Fire Hazard Severity Zone—the entire roof must comply with current Class A standards.
This local regulatory framework reinforces the importance of using certified materials and proper installation methods that have been verified by these standard tests.
Materials and Their Role in Achieving Class A Performance
To achieve a Class A fire rating under ASTM E108 or UL 790, every component of the roof assembly must contribute to its overall fire resistance. Typical materials and their functions include:
- Noncombustible Roof Coverings: Materials such as metal, concrete, or asphalt systems that are specifically formulated to resist flame spread.
- Fire-Resistant Underlayments and Insulation: Underlayments play a crucial role in preventing heat transfer to the roof deck. In Los Angeles, where buildings face both intense heat and potential ember attack, using underlayments that have been tested and certified is critical.
- Proper Fasteners and Sealants: These ensure that the roof covering remains securely attached even under the extreme conditions simulated during fire testing.
Using a fully assembled system that has been tested as a whole is key. In many cases, manufacturers provide detailed installation instructions that must be followed precisely to maintain the Class A rating.
Permitting, Compliance, and Inspections in Los Angeles
Before any roofing project commences in Los Angeles, obtaining the proper permits is essential. Local permitting authorities will review the project to ensure that the roof assembly meets the requirements outlined in the local building codes:
- Detailed Plans: Construction documents must show that the roof covering, underlayment, and any insulation or additional layers have been tested as part of an assembly that meets ASTM E108 or UL 790 standards.
- On-Site Inspections: Throughout the project, inspectors verify that the materials and installation practices conform to the approved plans and local codes. Any deviation from the tested assembly may result in delays or require re‑inspection.
- Final Approval: Only after successful inspection will the roof be approved for occupancy, ensuring that it has the desired fire resistance to protect against wildfires.
The Bottom Line for Los Angeles Roofs
For building owners, contractors, and architects in Los Angeles, understanding and applying the results of ASTM E108 and UL 790 fire tests is critical. In an environment where wildfires pose a constant threat, a Class A roof assembly is not just an option—it’s a necessity. Adhering to these standards protects property, ensures code compliance, and can even lower insurance costs.
Explore Our Metal Roofing Solutions
At Rain Gutter Pros, we specialize in high‑quality metal roofing systems that not only meet but exceed Class A requirements. Our metal roofs are designed to deliver outstanding fire resistance as verified by ASTM E108 and UL 790 testing, ensuring your building in Los Angeles is safe, durable, and compliant with local regulations.
Visit our website at raingutterprosinc.com to learn more about our services and request a free consultation today.