Technical Standard
ASTM E84 Fire Ratings: Class A, B, C for Wallcovering
The definitive guide to fire testing standards for commercial wallcovering — ASTM E84 (Steiner Tunnel Test), flame spread index, smoke developed index and what Class A, B and C mean for your specification.
Key Takeaways
- See detailed technical sections below.
What Is ASTM E84 and How Does It Work?
ASTM E84 (also known as the Steiner Tunnel Test or UL 723) is the standard test method for surface burning characteristics of building materials. A 24-foot sample is mounted in a tunnel and exposed to a controlled flame for 10 minutes. Two measurements are taken:
- Flame Spread Index (FSI): How quickly and far the flame travels across the material surface
- Smoke Developed Index (SDI): How much smoke the material produces during combustion
What Do the Fire Classes Mean?
| Class | Flame Spread Index | Smoke Developed Index | Typical Requirement |
|---|---|---|---|
| Class A | 0 – 25 | 0 – 450 | Hospitals, schools, hotels, high-rise, assembly |
| Class B | 26 – 75 | 0 – 450 | Some commercial, corridors, lobbies |
| Class C | 76 – 200 | 0 – 450 | Residential, some low-occupancy commercial |
Key point: Most commercial projects require Class A. Always verify with your local Authority Having Jurisdiction (AHJ) — code requirements vary by occupancy type, building height and location within the building.
How Does Natural Wallcovering Perform?
| Material | Typical Rating (on gypsum board) | Notes |
|---|---|---|
| Grasscloth (paper-backed) | Class A achievable | Depends on fiber weight and backing |
| Sisal | Class A achievable | Dense fiber structure helps |
| Cork | Class B typical | Cork is naturally fire-resistant; some achieve Class A |
| Paper weave | Class A typical | Lightweight, low fuel load |
| Vinyl (Type II) | Class A standard | Engineered for fire performance |
Critical: Fire ratings are system-dependent — the same wallcovering may rate differently on different substrates or with different adhesives. Always use the specific test report for your product + substrate combination.
What About NFPA 255?
NFPA 255 was withdrawn in 2011. It was the National Fire Protection Association's equivalent of ASTM E84 — technically identical test method. Modern building codes now reference ASTM E84 or UL 723 exclusively. If you encounter old specifications referencing NFPA 255, update them to ASTM E84.
How Do You Specify Fire Ratings?
- Check the building code: IBC Chapter 8 covers interior finishes — identify required class for your occupancy and building element
- Request the test report: Ask the manufacturer for the ASTM E84 test report specific to your product
- Verify the substrate: The report must match your installation substrate (typically Type X gypsum board)
- Document in specifications: Reference the specific ASTM E84 class in your wallcovering specification — see specification guide
- Keep the report on file: Building inspectors may request it during construction
Frequently Asked Questions
Does natural wallcovering pass ASTM E84 Class A?
Many natural wallcoverings achieve Class A when adhered to gypsum board substrate. The rating depends on the specific material, backing and installation method. Always request the specific test report for your product.
Is NFPA 255 still valid?
No. NFPA withdrew NFPA 255 in 2011 because it was redundant with ASTM E84. Modern building codes reference ASTM E84 or UL 723 exclusively.
Who determines the required fire class for my project?
Your local Authority Having Jurisdiction (AHJ) and the applicable building code (typically IBC) determine the required class based on occupancy type and location within the building.
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