While European projects reference EN 13501-1, North American building codes work with a different system: ASTM E84, the Standard Test Method for Surface Burning Characteristics of Building Materials. If you distribute acoustic panels in the United States or Canada, understanding this test — and the paperwork behind it — is essential for passing submittals.
What the test measures
In the ASTM E84 test, a 7.3-meter sample is installed on the ceiling of a horizontal tunnel and exposed to a controlled gas flame. Instruments record two indices over a ten-minute burn:
- Flame Spread Index (FSI) — how quickly flames travel along the surface. Red oak is the 100 reference; inorganic reinforced cement board is 0.
- Smoke Developed Index (SDI) — how much smoke the material generates, again relative to the red oak reference.
How the classes are defined
Most US building codes group interior finishes into three classes:
| Class | Flame Spread | Smoke Developed |
|---|---|---|
| Class A (or I) | 0–25 | 0–450 |
| Class B (or II) | 26–75 | 0–450 |
| Class C (or III) | 76–200 | 0–450 |
Class A is the default requirement in most commercial occupancies — offices, schools, healthcare and places of assembly — which is why American specifiers so often write “acoustic panel, Class A per ASTM E84” into their submittal packages.
Reading the report like a pro
A legitimate ASTM E84 report names the accredited laboratory (for example Intertek, UL or SGS), lists the exact product as tested, and shows both FSI and SDI numbers — not just the word “Class A”. Two details matter:
- Construction matters. The tested assembly must match the shipped product. If a panel is tested bare but you ship it with a different coating or backing, the rating may not carry over.
- Class B is not a failure. For many applications — retail interiors, some residential and hospitality zones — Class B is fully acceptable and sometimes allows more design freedom in materials. Match the class to the code requirement of the actual room.
EN 13501-1 versus ASTM E84
Buyers often ask whether a B-s1,d0 European rating automatically equals Class A. It does not — the test methods differ — but well-manufactured PET-based acoustic panels typically perform strongly in both systems. Ask your supplier for both reports; a manufacturer serving global markets should hold current certificates for each.
MST Acoustics for North American buyers
Our acoustic wall panels and wood slat panels are tested to ASTM E84 Class B, with reports available for submittal packages, and several PET panel series achieve Class A performance. We support US and Canadian distributors with samples, technical data sheets and absorption data (ISO 354 / ASTM C423) so your project documentation is complete from the first tender to the final inspection.
