ASTM E 84 (Tunnel Test) Surface Burning Characteristics of Building Materials

Specifications, Standards & Certificates

ASTM E84 no longer applies to flooring installations. See ASTM E 648 for current test method.

ASTM E84 is a measure of the relative burning characteristics of building materials as measured by flame spread and smoke density developed. The test fixture is comprised of a test chamber or box approximately 2 feet wide x 1 foot high and 25 feet long. The sample is mounted on the ceiling of the chamber. At one end of the chamber is the flame source (two gas burners) delivering flame upward against the surface of the sample. The gas burners release heat at a rate of approximately 5,000 btu min and create gas temperatures near the specimen surface of up to 1600F. The test duration is 10 minutes. The maximum flame spread is measure. The smoke is directed to the end of the tunnel where it passes through an optical measuring device (photometer system). The measurements are compared to those of 1/2″ thick select grade red oak, which is rated as 100. A product with flame spread rating of 25 and a smoke developed rating of 50 is commonly referred to as a 25/50 rated material. ASTM E84 is considered to be a medium-scale test and has been widely adopted for use by the building code authorities to regulate the use of interior finish materials.

It should be noted that methods and devices used for mounting and supporting the test specimen could influence the flame spread and smoke developed ratings. Testing of materials that drip, melt, or delaminate to such a degree that the continuity of the flame front is destroyed results in low flame spread indices that do not relate directly to indices obtained by testing materials that remain in place. NFPA 255 and UL 723 are similar to ASTM E84.


ClassFlame SpreadSmoke development
A0 – 25450
B26 – 75450
C76 – 200450
Updated on May 12, 2023