Fire Safety in Commercial Acoustic Design: Understanding ASTM E84 Class A and EN 13501-1

Commercial acoustic materials are increasingly used in offices, hotels, schools, restaurants, healthcare facilities, conference centers, and other public buildings. While sound absorption and interior appearance are important design considerations, fire safety is often the factor that determines whether an acoustic product can be approved for a project.

For architects, general contractors, distributors, and building material procurement teams, terms such as ASTM E84 Class A, EN 13501-1 B-s1,d0, and fire-rated wall panels frequently appear in technical specifications.

However, these classifications do not all measure the same fire performance characteristics. A product advertised as flame-retardant is not automatically suitable for every commercial application, and a test report for one PET panel configuration does not necessarily cover every thickness, color, or composite construction.

This guide explains the differences between North American and European fire testing standards, compares flame-retardant PET manufacturing methods, and outlines the technical documentation required to qualify acoustic products for commercial construction projects.

1. Why Fire Safety Is a Mandatory Consideration in Commercial Acoustic Design

Commercial buildings have different fire safety requirements depending on their occupancy, building height, fire protection systems, and the location of interior finishes.

Materials installed in a private office may be subject to different requirements from materials used in:

• Public corridors
• Exit stairways
• Hotel guest areas
• Schools and universities
• Shopping centers
• Hospitals
• Restaurants
• Conference facilities
• Public assembly spaces

Acoustic products are commonly installed on walls, ceilings, suspended structures, and workstation furniture. Each application may have different compliance considerations.

North American commercial projects

In the United States, the International Building Code (IBC) establishes requirements for interior wall and ceiling finishes.

The permitted classification depends on several factors, including:

• Occupancy classification
• Whether the building is sprinklered
• Whether the product is installed in a room, corridor, or exit enclosure
• Applicable exceptions and alternative test methods
• The locally adopted building and fire codes

Under the 2021 IBC Section 803, interior wall and ceiling finishes are classified according to their Flame Spread Index (FSI) and Smoke-Developed Index (SDI) when ASTM E84 or UL 723 is used.

The code recognizes three principal classes:

• Class A
• Class B
• Class C

Class A is the most restrictive of these three surface-burning classifications, but it is not universally required for every interior finish in every commercial building.

For example, the requirements for protected corridors and exit enclosures may differ from those for ordinary occupied rooms.

The 2021 International Building Code also recognizes NFPA 286 as an alternative test route for certain interior finish applications, subject to its prescribed acceptance criteria.

Reference: International Code Council – 2021 IBC, Chapter 8.

European commercial projects

European projects commonly use the Euroclass system under EN 13501-1.

The applicable classification depends on:

• Building use
• Product application
• Location within the building
• National building regulations
• Relevant product standards and intended use

A specification may require B-s1,d0 for a particular interior wall or ceiling application, but this should never be assumed to be a universal requirement across Europe.

Architects and contractors must confirm the applicable national regulations and project specification.

2. ASTM E84 Class A: Understanding the North American Fire Test

ASTM E84 is titled:

Standard Test Method for Surface Burning Characteristics of Building Materials.

It evaluates the relative surface-burning characteristics of building materials under controlled laboratory conditions.

The test measures two principal parameters:

Flame Spread Index (FSI)

FSI indicates the relative spread of flame along the exposed surface of the test specimen.

A lower FSI generally indicates less flame spread under the specified test conditions.

Smoke Developed Index (SDI)

SDI measures the relative amount of smoke developed during the test.

Both values are reported because a material’s flame spread behavior and smoke development are separate characteristics.

What does Class A mean?

Under the commonly referenced IBC classification system, the three classes are:

For a product to meet the Class A limits, both reported indices must fall within the specified ranges.

For example:

A PET acoustic panel with:

• FSI: 15
• SDI: 100

would fall within the Class A numerical limits when classified under the applicable code provisions.

A product with:

• FSI: 20
• SDI: 500

would not meet the Class A SDI limit.

Important: ASTM E84 itself reports flame spread and smoke-developed indices. The Class A, B, and C groupings are established through the relevant building code classification provisions.

What does ASTM E84 actually test?

The test uses a controlled fire exposure in a horizontal tunnel apparatus. The specimen is mounted in the test position, with its exposed surface facing the ignition source.

The standard is intended for comparing surface-burning behavior. It is not a full-scale building fire simulation.

The currently active edition as of November 2026 is ASTM E84-26a.

Reference: ASTM International – ASTM E84-26a.

ASTM specifically notes that its results are comparative measurements under controlled conditions and do not independently establish the complete fire risk of a material in actual building conditions.

The way a specimen is supported and mounted during testing can also affect the reported result.

This is particularly important for lightweight PET acoustic panels and composite wood slat panels.

3. EN 13501-1: Understanding European Reaction-to-Fire Classification

EN 13501-1 is the European classification standard for the reaction-to-fire performance of construction products.

Unlike the simplified Class A, B, and C system commonly used with ASTM E84, the Euroclass system combines several characteristics.

For most wall and ceiling lining products, the main classifications are:

A1, A2, B, C, D, E, and F

The classifications provide information about how a product contributes to fire development.

Understanding B-s1,d0

One commonly encountered classification for commercial interior materials is:

B-s1,d0

Each part communicates different information.

What is measured?

For Class B products, the classification generally involves two test methods:

EN 13823 – Single Burning Item (SBI) test

This evaluates fire growth and other reaction-to-fire characteristics, including heat release, smoke production, and flaming droplets.

EN ISO 11925-2 – Small flame test

This evaluates the ignitability of the product when exposed to a small flame source.

The classification criteria are defined through the European classification framework, including Commission Delegated Regulation (EU) 2016/364.

References:

• European Commission – Regulation (EU) 2016/364
• RISE – European Fire Classification of Construction Products

What does B-s1,d0 mean for acoustic panels?

For architects and contractors, B-s1,d0 provides information about three important fire characteristics:

1. The product meets the requirements for Euroclass B under the relevant reaction-to-fire classification procedure.
2. Its smoke production falls within the s1 category.
3. It meets the d0 criterion for flaming droplets and particles.

This makes it a useful specification for evaluating acoustic wall and ceiling materials in projects where the classification is required.

However, the classification must be supported by the appropriate test and classification documentation for the actual product construction.

4. ASTM E84 Class A vs. EN 13501-1 B-s1,d0: Can They Be Compared?

This is one of the most common questions from international building material buyers.

A manufacturer may advertise:

ASTM E84 Class A + EN 13501-1 B-s1,d0

Does this mean the two classifications are equivalent?

No.

They are based on different test procedures, measurement systems, and classification criteria.

A product achieving ASTM E84 Class A does not automatically qualify for EN 13501-1 B-s1,d0.

Likewise, a product classified B-s1,d0 should not automatically be marketed as ASTM E84 Class A.

5. Are Acoustic Panels Fire Retardant?

The answer is: Not automatically.

Acoustic panels are manufactured from different materials, and their fire performance varies according to their composition and manufacturing process.

Common acoustic products include:

• PET polyester acoustic panels
• Polyester felt panels
• Wood slat acoustic panels
• MDF acoustic panels
• Fabric-wrapped fiberglass panels
• Mineral fiber ceiling panels
• Foam acoustic panels
• Composite decorative acoustic boards

These materials do not have identical fire behavior.

Even products belonging to the same material category can have different fire performance because of:

• Raw material formulation
• Density
• Thickness
• Flame-retardant additives
• Surface treatments
• Adhesives
• Decorative facings
• Composite backing materials

Are ordinary PET acoustic panels automatically flame-retardant?

No.

PET is a thermoplastic polymer. Standard polyester fiber should not automatically be assumed to meet a commercial fire classification.

A PET acoustic product may be manufactured with flame-retardant additives or receive a suitable flame-retardant treatment.

However, the finished product must still be tested against the required standard.

What about an ASTM E84 Class A acoustic desk panel?

A buyer searching for an ASTM E84 Class A acoustic desk panel should check whether the report covers the actual desk screen or acoustic panel construction.

A report for a 9 mm PET wall panel does not automatically cover a 12 mm freestanding screen or a desk divider with a different mounting configuration.

The product category, tested sample, exposed surfaces, and mounting arrangement must be reviewed before approving the material.

6. Intrinsically Flame-Retardant PET vs. Post-Applied Flame-Retardant Coatings

There are two broad approaches to achieving flame-retardant performance in polyester-based materials.

The first introduces flame-retardant functionality into the fiber or polymer during manufacturing.

The second applies flame-retardant chemicals through a finishing process after the fiber or material has been produced.

Neither approach should be accepted based on its name alone. The finished acoustic panel needs to meet the required test classification.

Method 1: Flame-Retardant PET Fiber

Flame-retardant performance can be introduced into polyester fibers through:

• Flame-retardant additives incorporated during polymer processing
• Flame-retardant components incorporated into the polymer structure
• Suitable flame-retardant fiber formulations

The material is then converted into polyester fiber and processed into acoustic felt.

Advantages:

More integrated fire-retardant functionality: When the flame-retardant component is incorporated into the polymer or fiber structure, the functionality is not dependent solely on an external surface coating.

Potentially better long-term durability: Inherently flame-retardant fibers generally offer better resistance to loss of fire-retardant performance during normal use than less durable surface-applied treatments.

More consistent treatment through the fiber: The flame-retardant formulation can be distributed through the material rather than relying entirely on the exposed surface.

However, the durability and performance still depend on the actual formulation and manufacturing process.

Method 2: Post-Applied Flame-Retardant Treatment

This approach applies a flame-retardant chemical finish to an existing material.

Possible methods include:

• Spraying
• Padding
• Impregnation
• Coating
• Resin-based finishing

The treatment creates a flame-retardant effect through its interaction with the material during exposure to heat or flame.

Advantages:

• Can be applied to an existing production material
• May reduce the need for changing the original fiber formulation
• Offers manufacturing flexibility
• Can be suitable for specific product applications

Potential limitations:

The long-term performance depends on:

• Chemical formulation
• Coating adhesion
• Penetration into the fiber structure
• Curing conditions
• Surface coverage
• Moisture exposure
• Cleaning methods
• Abrasion and service conditions

Some post-applied treatments can achieve high durability when they chemically bond or polymerize within the fiber structure.

Others rely more heavily on surface coatings and binders and may be less durable.

The US National Academies’ review of flame-retardant textiles discusses this distinction, noting that durability of after-treated materials depends on how effectively the formulation bonds to the fiber structure.

Reference: National Academies – Flame-Retardant Composition in Fabrics: Durability and Permanence.

Comparison

7. Why Composite Acoustic Panels Need Special Attention

This is particularly important for wood slat acoustic panels.

A typical composite acoustic panel may include:

• MDF slats
• Wood veneer or decorative surface
• PET acoustic backing
• Adhesive
• Surface coating
• Mounting accessories

Even when the PET backing has a satisfactory fire test result, the complete composite panel may behave differently.

For example:

A 12 mm flame-retardant PET backing

does not automatically make:

A complete wood slat acoustic panel with MDF, veneer, adhesive, and backing

compliant with the same fire classification.

The decorative surface and adhesive can influence the behavior of the finished construction.

The same applies to:

• PET desk dividers
• Acoustic baffles
• Fabric-wrapped acoustic panels
• Laminated decorative panels
• Composite wall systems

ASTM E84 includes specimen mounting and support considerations. ASTM E2404 also provides specimen preparation and mounting procedures for textile, polymeric, and wood wall or ceiling coverings evaluated under ASTM E84.

Reference: ASTM E2404 – Specimen Preparation and Mounting for Wall and Ceiling Coverings.

For commercial procurement, ask the manufacturer whether the report covers the actual composite construction or only one of its raw materials.

8. Fire-Rated Wall Panels: Understanding the Terminology

The expression fire-rated wall panel can refer to different things.

This is an important distinction in commercial construction.

Reaction-to-fire classification

This evaluates how a material contributes to fire development.

Examples include:

• ASTM E84 Class A
• EN 13501-1 B-s1,d0
• Other relevant reaction-to-fire classifications

These are commonly relevant when specifying interior wall and ceiling finishes.

Fire-resistance-rated wall assembly

This refers to the ability of a complete wall construction to maintain specific performance under fire exposure for a defined period.

For example, a wall assembly might be specified as:

• 30-minute fire resistance
• 60-minute fire resistance
• 90-minute fire resistance
• 120-minute fire resistance

In North America, ASTM E119 is used to evaluate fire resistance of building elements and assemblies.

In Europe, EN 13501-2 provides the classification framework for fire resistance and smoke-control test results.

For example, an EI 60 classification relates to integrity and insulation performance for 60 minutes under the applicable test and classification procedure.

References:

• ASTM E119 – Fire Tests of Building Construction and Materials
• European Commission – Fire Resistance Classification

9. What Should Architects and General Contractors Include in a Fire Compliance Submittal?

For commercial projects, the fire approval process should be based on a complete technical document package.

A single marketing statement or certificate image is rarely enough for a demanding construction specification.

A useful submittal package should include the following.

A. Product identification

• Manufacturer
• Product name
• SKU or model number
• Material composition
• Panel thickness
• Density or area weight
• Dimensions
• Color
• Surface finish
• Composite construction details

B. Fire test documentation

For North American projects:

• ASTM E84 test report
• Flame Spread Index
• Smoke Developed Index
• Report number
• Laboratory information
• Specimen description
• Test date
• Mounting and support conditions

For European projects:

• EN 13501-1 classification report
• Classification
• Applicable test reports
• EN 13823 results where relevant
• EN ISO 11925-2 results where relevant
• Specimen description
• Mounting conditions
• Field of application

C. Installation documentation

• Installation manual
• Adhesive specification
• Mechanical fixing details
• Substrate requirements
• Air-gap details
• Joint and edge treatment
• Suspension details for baffles
• Fixing and support requirements

The declared performance of a construction product is expected to be achieved under the conditions of correct installation. The European Commission’s Construction Products Regulation guidance emphasizes the importance of manufacturer installation instructions.

Reference: European Commission – Construction Products Regulation FAQs.

D. Quality assurance and traceability

For larger projects, it is also useful to provide:

• Factory quality-control procedures
• Batch identification
• Raw-material specifications
• Change-control procedures
• Product consistency records
• Sample approval records

The objective is to demonstrate that the product supplied to the construction site is consistent with the product described in the approved test documentation.

10. CE Marking, Declaration of Performance, and Fire Test Reports

For European construction projects, buyers may also request:

• CE marking
• Declaration of Performance (DoP)
• Product technical documentation
• Classification reports
• Installation instructions

However, CE marking and DoP requirements depend on the product being covered by a relevant harmonised technical specification or obtaining an applicable European Technical Assessment (ETA).

A CE mark should not be presented as automatic proof of a particular fire classification for every product.

Similarly, an ASTM E84 laboratory report and a European EN 13501-1 classification report serve different purposes.

The relevant European CPR provisions explain the information required in a Declaration of Performance, including the product type, intended use, technical specification, and declared performance.

Reference: EU Construction Products Regulation – Consolidated Text.

For manufacturers supplying multiple countries, it is important to prepare a documentation package suitable for each target market.

11. How to Evaluate an Acoustic Panel Supplier’s Fire Claims

Before accepting a supplier’s fire performance statement, procurement teams should check several details.

An independent laboratory report is valuable, especially where the laboratory is accredited for the relevant test method.

However, buyers should distinguish between:

• A laboratory test report
• A classification report
• A product certification or listing
• A manufacturer’s declaration

These documents are related but are not interchangeable.

12. Fire Safety Checklist for Commercial Acoustic Projects

Before approving a PET acoustic panel, acoustic desk divider, or wood slat acoustic panel, use this checklist.

Conclusion: Fire Compliance Is a Product Specification, Not a Marketing Claim

Fire performance is one of the most important qualification criteria for acoustic materials used in commercial buildings.

For North American projects, ASTM E84 Class A provides a recognized surface-burning classification based on Flame Spread Index and Smoke Developed Index.

For European projects, EN 13501-1 provides a broader reaction-to-fire classification system, including flame behavior, smoke production, and flaming droplets.

ASTM E84 Class A and EN 13501-1 B-s1,d0 should never be treated as automatically equivalent.

For PET acoustic materials, flame-retardant performance can be developed through integrated fiber formulations or suitable post-applied treatments. Their long-term suitability depends on material chemistry, manufacturing control, product construction, and supporting test evidence.

For wood slat acoustic panels and other composite products, the complete construction must be considered rather than relying only on the fire rating of the PET backing.

For architects, contractors, and distributors, the most reliable approach is to evaluate:

The exact product + the applicable fire standard + the full laboratory report + the intended installation + the local building requirements.

At the procurement stage, ask the manufacturer to provide the applicable ASTM E84 or EN 13501-1 documentation, technical datasheet, material construction, and installation instructions.

A product that can demonstrate its fire performance with traceable documentation is much easier to specify, approve, and supply for international commercial projects.