Class A Fire Ratings in Acoustic Products

Designing a an acoustically treated space is a precise art that involves carefully balancing the room’s aesthetics and acoustics to create an auditory masterpiece.

But what if that canvas were to catch fire?

As captivating as the pursuit of acoustical perfection may be, it cannot overshadow the essential safety features of the room’s design.

When it comes to building responsibly, a Class A fire rating in acoustic products isn’t just a nice-to-have option – it’s vital.

If you want to create a space that looks great, sounds better, and is safe for its occupants to be in, the first things you’ll encounter when looking for soundproofing tips is that you’ll need to utilize fire-resistant wall panels and fire-rated ceiling panels in your build.

Today, we’ll discuss what a Class A fire rating means and why it matters.

The Science of Flame Spread

In building construction, interior finish materials play a key role in determining how a fire behaves, influencing both the way it spreads and the rate at which it spreads.

This became glaringly apparent in the late ‘40s and early ‘50s when combustible acoustical tiles and foams contributed to several infernos that resulted in tragedies. To make matters worse, in many of these cases, the conventional materials didn’t just act as kindling.

Over the following decades, lawmakers revised fire protection building codes and standards, leading to much stricter regulation over the types of materials allowed in a building depending on their fire spread characteristics.

In an effort to standardize fire safety standards, one fire endurance test has emerged as the industry standard for fire-rating materials—ASTM E-84.

What Is ASTM E-84?

ASTM E-84, also known as the Standard Test Method for Surface Burning Characteristics of Building Materials, is a test that measures the flame spread and smoke development of materials. This helps to evaluate how fire behaves over a surface. The test provides a flame spread rating, indicating the relative rate at which fire will travel over the material’s surface, and a smoke development rating, indicating how much smoke is produced over a given time period. It does not measure heat transmission or the effect of aggravated flame spread due to proximity to other combustible objects.

How Is This Tested?

When evaluating building products or materials for fire safety, a dozen factors may be considered. For instance, there’s ignition temperature, flame spread, and smoke toxicity. However, in terms of design, flame spread is often the key factor to be tested.

The test is frequently referred to as the Tunnel Test or Steiner Tunnel Test—named after A.L. Steiner, formerly of Underwriters’ Laboratories in Chicago—and has been the industry standard for nearly a century. Here’s how the test is conducted1:

  • Sample preparation – The material (18 inches wide by 25 feet long) is attached to the underside of a removable top panel.
  • Application of flame – A regulated gas flame is introduced at one end, while a constant draft (240 feet per minute) moves through the tunnel.
  • Observation – The progress of the flame front, also known as flame front advancement is observed through side windows, recorded, and timed for 10 minutes.
  • Calculation of rating – Based on these observations, the flame spread rating is calculated.

What Are the Flame Spread Ratings?

Flame spread ratings are crucial in understanding how a fire will behave across different types of building material. When the rating test was first developed, materials were classified into three categories, A, B, and C. However, today, the NFPA Standard 101 has expanded these classifications to include five categories, A-E.

  • Class A flame spread rating 0-25 – Class A materials do not burn well and are very unlikely to contribute fuel to a fire, which is why many facilities require a Class A rating for their building material. Examples include:
    • Brick
    • Concrete
    • Stone
    • Fire-retardant treated wood
    • Fire-resistant insulation
    • Gypsum wallboard
    • Fiber cement exterior materials
    • Bonded acoustical cotton
  • Class B flame spread rating 26-75 – Class B materials are more combustible than Class A, offering moderate resistance to flame spread. They can be used in areas where some fire resistance is required. Examples might include:
    • Lower-grade fire-retardant wood
    • Certain types of foam insulation
    • Some roofing materials
  • Class C Flame Spread Rating (76-200) – Class C materials have less fire resistance and are more susceptible to flame spread. They are often found in non-critical areas. Examples might include:
    • Untreated wood (e.g., plywood, fiberboard)
    • Some interior finishes
    • Fewer types of roofing materials due to modern fire codes
  • Class D Flame Spread Rating (201-500) – Class D materials have limited fire resistance and can significantly contribute to flame spread in a fire event. Common materials include:
    • Certain metals that can act as fuel in specific conditions
    • Some chemical substances
    • Materials used in industrial settings
  • Class E Flame Spread Rating (Over 500) – Class E materials are highly susceptible to fire and are prone to rapid flame spread, contributing fuel to a fire. Examples may include:
    • Some electrical components like wiring, circuit breakers, and outlets
    • Certain plastics and foams
    • Highly flammable substances

Significance of Class A Fire Ratings In Acoustic Products

In modern architectural design, acoustic products are regularly applied to ceilings and walls to enhance sound quality and aesthetics. Many of these conventional acoustic products are porous and made of materials that could be susceptible to ignition. If these items are not carefully selected and treated, they could accelerate the spread of fire, negating the inherent fire resistance of the walls and ceilings.

So, when it comes to designing spaces with specific acoustic requirements, safety cannot be an afterthought. The utilization of Class A fire-rated materials in acoustic products can open up several advantages, including:

  • Fire resistance – Traditional acoustic materials are often susceptible to fire, given the nature of their design and the substances used. Implementing Class A fire-rated products ensures resilience against potential flame hazards. This classification means the materials are highly resistant to fire, making them reliable in preserving both the structure and the lives within.
  • Compliance with regulations – In many jurisdictions, fire safety regulations and building safety codes mandate the use of Class A fire-rated materials, particularly in public and commercial buildings. These stringent standards were designed to strengthen the integrity of structures and the safety of their occupants. By adhering to these regulations, developers, and architects demonstrate a commitment to responsible construction practices.
  • Peace of mind – Knowing that a space is designed with safety at the forefront adds an extra layer of comfort. Therefore, using Class A fire-rated acoustic panels in your project can provide peace of mind.
  • Legal liability protection – For the owner of a building, failure to comply with fire safety standards can result in severe legal consequences. Should a fire breakout and the materials used are discovered to be below the required safety standards, the legal ramifications could be devastating. Lawsuits, fines, damage to reputation, and even jail time, are just a few of the potential outcomes.
  • Lower insurance premiums – Similarly, insurance companies care deeply about the safety standards of a building, especially a commercial one. A building that uses Class A fire-rated acoustic materials—even if it may not be legally necessary—can result in lower premiums that act as a financial incentive for property owners to prioritize fire safety in their designs.
  • Environmentally friendly – Many of the Class A fire-rated materials are made from sustainable or recycled materials. Using these materials can uphold environmentally responsible building practices while simultaneously ensuring the highest standards of safety.

Acoustical Surfaces: Fire Safety Meets Acoustic Quality

Whenever you design or build a space, form and function must be balanced by safety. In the intricate dance of architecture and interior design, acoustical surfaces play a vital role in enhancing both aesthetics and sound mechanics. But beyond the allure of design and the innovation of sound control for reduction of flutter echoes, lies the fundamental responsibility to safeguard life and property.

Through the implementation of Class A fire ratings and adherence to other safety standards, this balance can be achieved. By selecting materials that not only fulfill the artistic vision but also align with stringent fire safety regulations, designers and builders create spaces that resonate without sacrificing safety.

At Acoustical Surfaces, we offer several acoustic products that have a Class A fire rating, including but not limited to:

  • Echo Eliminator made from bonded acoustical cotton
  • CFAB Cellulose-based acoustical and thermal panels
  • Fire retardant Echo Barrier
  • Poly Max ceiling and wall panels

Whether you need fire-resistant wall panels or fire-rated ceiling panels or just want advice on the proper way to fireproof an acoustic space, our experts can match you with the right solutions to meet both your design needs and safety requirements.


  1. Firesafety Search. Steiner Tunnel Withstands the Test of Time.
  2. ASTM. Standard Test Method for Surface Burning Characteristics of Building Materials.

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