What does Class A mean for wallcovering?

In the building code, Class A means an ASTM E84 or UL 723 flame spread index of 0-25 and a smoke-developed index of 0-450. W-101 and CCC-W-408D set a tighter smoke limit of 50 for their Class A or for all types.

Is NFPA 286 better than ASTM E84?

They measure different things. ASTM E84 is a comparative tunnel test of surface flame spread and smoke. NFPA 286 burns a full room corner and measures heat release, smoke, flashover and fire growth. The code treats a product meeting the NFPA 286 criteria as complying with Class A.

Does a Class A rating apply to any wall?

It applies to the tested assembly. Koroseal reports its ASTM E84 Class A result on GRC board with A-848-B adhesive and its NFPA 286 result on 5/8 in Type X gypsum board with A-848-B adhesive. Different substrates, adhesives or hanging over existing wallcovering should be reviewed with the manufacturer and AHJ.

Which class does my corridor need?

It depends on occupancy, location, sprinkler protection and the code edition your jurisdiction adopted. Check Table 803.13 of your adopted building code or the applicable NFPA 101 chapter, and confirm with the AHJ.

Specification guide

Fire Ratings for Commercial Wallcovering: ASTM E84, NFPA 286 and Test Conditions

Reviewed October 27, 2026 by the Commercial Wallcoverings team. Sources listed below.

Under ASTM E84 as used by the building code, Class A means a flame spread index of 0-25, Class B 26-75 and Class C 76-200, each with a smoke-developed index of 0-450. NFPA 286 is a room corner test that the code accepts as equivalent to Class A when five acceptance criteria are met. Both results describe the substrate and adhesive that were tested, so read the footnotes and confirm requirements with the authority having jurisdiction.

ASTM E84: the tunnel test

ASTM E84 is "a 10-min fire-test response method" that exposes "a nominal 24-ft (7.32 m) long by 20-in. (508 mm) wide specimen" in the ceiling position, face down, to a controlled flame and airflow. It is "intended to provide only comparative measurements of surface flame spread and smoke density," calibrated against select grade red oak and fiber-cement board. The standard warns that it "does not by itself incorporate all factors required for fire-hazard or fire-risk assessment." Koroseal fact sheets list this test as "NFPA 255 (ASTM E-84, CAN S102M) Tunnel Test."

Class A, B and C

Building codes group ASTM E84 (or UL 723) results into three classes. Some wallcovering standards set tighter smoke limits than the code.

Document	Class or type	Flame spread index	Smoke-developed index
Building code, Section 803.1.2	Class A	0-25	0-450
Building code, Section 803.1.2	Class B	26-75	0-450
Building code, Section 803.1.2	Class C	76-200	0-450
WA W-101 (2025)	Class A	0-25	0-50
WA W-101 (2025)	Class B	26-75	0-100
CCC-W-408D	Types I, II and III	25 max	50 max

The code ranges are quoted from the 2025 California Building Code and match the 2021 IBC text as adopted in Texas for industrialized housing and buildings. The same ranges appear in the 2012 NFPA 101 Life Safety Code, as summarized by the Minnesota Department of Health.

NFPA 286: the room corner test

NFPA 286, "Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth," lines a test room with the finish and burns a gas burner in a corner at 40 kW (plus or minus 1 kW) for 5 minutes, then at 160 kW (plus or minus 5 kW) for 10 minutes, as described by ICC-ES. It reports the rate of heat release, smoke obscuration, carbon monoxide and the extent of fire growth. It "is not meant to evaluate the fire resistance of assemblies."

The building code (Section 803.1.1.1) accepts NFPA 286 results when all five criteria are met:

"During the 40 kW exposure, flames shall not spread to the ceiling."
"The flame shall not spread to the outer extremity of the sample on any wall or ceiling."
"Flashover, as defined in NFPA 286, shall not occur."
"The peak heat release rate throughout the test shall not exceed 800 kW."
"The total smoke released throughout the test shall not exceed 1,000 m2."

Materials that meet these criteria "shall be considered to comply with the requirements of Class A." NFPA 101 (2012), Section 10.2.3.2, likewise allows NFPA 286 tested finishes where Class A is required, according to the Minnesota guidance.

Why substrate and adhesive matter

A fire rating describes the assembly that was tested. ASTM E84 notes that supporting materials under the specimen "has the ability to lower the flame spread index." W-101 states that, unless otherwise specified, testing "shall be conducted on glass reinforced cement board (GRC) or equivalent." Koroseal footnotes its results the same way: Class A "when applied to GRC board with A-848-B adhesive" and NFPA 286 "when applied to 5/8 in Type-X gypsum board with A-848-B adhesive."

The code also controls how a finish is applied. Section 803.15.4 requires a finish "not more than 1/4 inch (6.4 mm) thick" to be applied directly to the wall "without the use of furring strips." Section 803.7 requires expanded vinyl wall coverings to be "tested in the manner intended for use." Wolf-Gordon warns that hanging vinyl over existing vinyl "may significantly increase flammability and smoke generation." If your substrate, adhesive or existing wall finish differs from the tested assembly, raise it with the manufacturer and the authority having jurisdiction (AHJ).

Interior finish rules by occupancy: read the adopted code

Section 803.13 states that interior wall and ceiling finish "shall have a flame spread index not greater than that specified in Table 803.13 for the group and location designated." That table, titled "Interior Wall and Ceiling Finish Requirements by Occupancy," varies by occupancy group, by location (exits, corridors, rooms) and by sprinkler protection, and its footnotes change the result. NFPA 101 (2012), Section 10.2.8.1, allows Class C where Class B is required, and Class B where Class A is required, in sprinklered buildings for materials other than textiles, according to the Minnesota guidance. We do not reproduce occupancy tables here because the edition and local amendments differ by jurisdiction. Confirm the requirement for your project with the AHJ.

Checklist for a fire claim

Which test (ASTM E84, NFPA 286, NFPA 265) and which edition?
The numbers, not only the class: flame spread index and smoke-developed index.
Substrate and adhesive used in the test.
Which products and colorways the report covers. Koroseal posts ASTM E84 test reports by product in its technical library.
Whether your installation matches the tested assembly.

For durability grades see the Type I, II and III guide. Browse commercial wallcovering materials.

Questions

What does Class A mean for wallcovering?: In the building code, Class A means an ASTM E84 or UL 723 flame spread index of 0-25 and a smoke-developed index of 0-450. W-101 and CCC-W-408D set a tighter smoke limit of 50 for their Class A or for all types.
Is NFPA 286 better than ASTM E84?: They measure different things. ASTM E84 is a comparative tunnel test of surface flame spread and smoke. NFPA 286 burns a full room corner and measures heat release, smoke, flashover and fire growth. The code treats a product meeting the NFPA 286 criteria as complying with Class A.
Does a Class A rating apply to any wall?: It applies to the tested assembly. Koroseal reports its ASTM E84 Class A result on GRC board with A-848-B adhesive and its NFPA 286 result on 5/8 in Type X gypsum board with A-848-B adhesive. Different substrates, adhesives or hanging over existing wallcovering should be reviewed with the manufacturer and AHJ.
Which class does my corridor need?: It depends on occupancy, location, sprinkler protection and the code edition your jurisdiction adopted. Check Table 803.13 of your adopted building code or the applicable NFPA 101 chapter, and confirm with the AHJ.