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What Is a “Class A” Fire Rating?

U.S. Fire departments respond to over 1.5 million fire calls annually. These incidents cause numerous injuries, fatalities, and billions of dollars in damages. To protect homes and occupants, local building codes require measures such as the use of fire-retardant materials and fire systems.

Understanding how materials impact your home is crucial. Let’s explore Class A fire ratings and the materials that offer the best protection against accidental fires.

What Does Fire Resistance Mean? 

Fire resistance is the ability of materials to withstand fire and heat, slowing down or preventing the spread of flames and hot gases. In other words, fire-resistant materials help to contain a fire and limit the amount of damage it causes.

How is Fire-Resistance Determined? 

The three primary methods used to determine fire-resistance ratings include:

1. Standard Fire Tests

Standard fire tests are the most common method for determining fire resistance ratings. These tests expose materials in a controlled laboratory environment to a specific temperature curve that mimics a real fire.

Fire resistance ratings are measured by the duration these materials or assemblies can withstand fire without experiencing the following:

  • Flaming on the unexposed surface: The side of the material not directly exposed to the fire should remain flame-free.
  • Exceeding a temperature rise on the unexposed surface: The unexposed surface should not exceed a specified temperature rise to prevent hazards or ignition of nearby items.
  • Losing structural integrity: The material or assembly should maintain its structural integrity, avoiding collapse or cracking, to continue supporting the building elements above it.

2. Design Documentation from Approved Sources

Fire resistance ratings are sometimes determined using documented performance data for similar materials or assemblies. This data comes from reliable sources that have undergone fire testing and meet specific approval requirements.

3. Comparison of Fire Resistance and Design

Fire resistance ratings for specific building elements are determined by comparing the element’s design and materials to similar elements with known fire resistance ratings. This method relies on established fire resistance principles and requires qualified professionals to ensure accuracy.

The method for determining fire resistance ratings depends on building code requirements, material type and application, existing test data availability, and testing cost and feasibility. Building code authorities specify acceptable methods within their jurisdictions. Fire resistance testing should always be handled by a professional.

What is a Class A Fire Rating? 

The Class A fire rating is the most stringent standard available for building materials. It indicates excellent fire resistance and a flame spread rating between 0 and 25. Materials with this rating outperform Class B and Class C, providing superior protection against fires fueled by ordinary combustibles like wood, cloth, paper, and some plastics.

What Do Local Building Codes Say? 

Virginia’s building codes prioritize residential fire safety. The Virginia Residential Code (VRC) uses a performance-based approach, which means buildings must meet specific fire safety goals, such as:

  • Containing fires for a certain amount of time
  • Providing safe routes for occupants
  • Limiting the spread of fire to other parts of the building

To achieve these goals, the VRC requires passive and active fire safety features, which involve:

  • Passive Features: These include fire-resistant walls and compartmentation, which contain fires and limit their spread.
  • Active Features: These include fire alarms and sprinklers, which detect and suppress fires.

Combining performance standards with material regulations allows Virginia’s building codes to ensure a high level of fire safety in residential buildings. Contact a licensed architect, engineer, or building official for the most up-to-date and accurate information regarding building codes and home materials.

How to Protect Your Home Against Accidental Fire

Protecting your home against accidental fire is absolutely crucial. Here are a few ways you can do this:

Use Proper Construction Materials 

When building or repairing your home, combining ignition-resistant building techniques with Class A-rated materials is a great way to improve its fire resistance. While Class A materials are not always non-combustible, they do offer significant fire protection by slowing the spread of flames.


Roof coverings have various fire ratings, with Class A providing the best fire resistance. Fiberglass shingles, concrete, asphalt, and clay tiles are perfect examples of Class A roof coverings. Some roofing materials have a “by-assembly Class A fire rating.” That’s another way to say builders can insert materials like aluminum, rubber, and fire-resistant wood shake products between the roof sheathing and the covering to attain the rating.  

Wall Construction 

Fire resistance is a critical consideration when building interior walls and partitions, especially in non-symmetrical structures. Fire-resistant walls with smoke-tight properties help compartmentalize the building, slowing fire and smoke spread. Wall openings should also be fire-rated. The specific design of fire-resistant walls, including their height and structural performance under fire conditions, depends on the building’s fire safety plan.

Below-Grade Areas 

Recommendations for basement wall insulation thickness vary by climate zone, with R-15 being a potential starting point. It is important to consult local building codes or a qualified professional for specific requirements. Use moisture-resistant insulation like foam board instead of standard fiberglass batts, which may be unsuitable due to moisture concerns.

The recommendation for crawl space wall insulation thickness also varies by climate zone, so consult local building codes or a professional for guidance. Fiberglass batts are not effective due to potential moisture issues; consider rigid foam board insulation instead. A vapor retarder on the warm side of the insulation (typically the interior) is also highly recommended for unvented crawl spaces.

Insulation is an important aspect of heat retention and fire protection. Materials like vapor retarders, membranes, and single or multilayer foil insulation can also help you comply with local codes. 

Protect Your Home and Family with Class A Insulation

crew member carrying insulation panel

Many homeowners use active fire suppression systems, such as fire extinguishers and sprinklers, to manage minor fires. Fire-resistant walls, floors, and roofs are also useful in containing fires and slowing their spread. 

If you’d like to insulate low-lying areas such as your crawl space or basement, contact the experts at JES Foundation Repair. After thoroughly inspecting your home, we will provide a free estimate and customized recommendations. Our exclusive ExTremeBloc™ insulation panels offer durable, Class A fire rating, ensuring your family’s safety.

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    Crawl Space Insulation FAQs

    Costs vary based on crawl space condition, size, and required solutions. Our experts provide a no-obligation estimate after a free inspection, detailing costs and financing options.

    The R-value measures thermal resistance in materials like insulation. Higher values indicate better heat retention. Learn more about our reliable insulation and its R-value by contacting us to schedule a free inspection.

    Selecting the right insulation for a crawl space is unique to any other area of your home. Look for a ridged, closed-cell foam that provides a thermal barrier and has at least an R-10 value.

    Shaye Glisson

    Shaye Glisson

    Shaye is an SEO Content Writer for Groundworks with over twelve years of experience creating helpful content across various industries, including home services and retail. She is a Gulf Coast native and writes from her firsthand knowledge of the area's hurricane and flood impacts on the local community. In her free time, Shaye enjoys exploring the local food and music scenes.

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