According to NFPA 101, Life Safety Code, interior wall and ceiling finish materials are classified based on their Flame Spread Index (FSI) and Smoke Developed Index (SDI) as determined by the ASTM E84 or UL 723 test. The classifications are as follows:

Class A: Flame Spread Index 0–25

Class B: Flame Spread Index 26–75

Class C: Flame Spread Index 76–200

A material with a flame spread rating of 82 falls within the 76–200 range, which corresponds to a Class C interior finish. The Smoke Developed Index for all classes must not exceed 450.

A. Class A: This classification is for materials with a Flame Spread Index of 25 or less. An index of 82 is too high for this class.

B. Class B: This classification is for materials with a Flame Spread Index between 26 and 75. An index of 82 is outside this range.

D. Plenum-grade: This term describes materials suitable for use in air plenums, which have stricter requirements (typically FSI ≤ 25, SDI ≤ 50), but it is not a standard interior finish classification.

1. NFPA 101®, Life Safety Code®, 2021 Edition. Section 10.2.3.4, "Interior Wall or Ceiling Finish Classification." This section explicitly defines the Flame Spread Index and Smoke Developed Index ranges for Class A, B, and C finishes.

2. SFPE, Handbook of Fire Protection Engineering, 5th Edition. Chapter 16, "Surface Fire Spread," Section 16.4.1, "Steiner Tunnel Test (ASTM E84)." Table 16.2 details the classification of interior finishes as used in U.S. model building codes, aligning with the NFPA 101 definitions.

3. NFPA, Fire Protection Handbook, 21st Edition. Section 8, Chapter 3, "Interior Finish," Table 8.3.1, "Interior Finish Classifications." This table provides the standard classification scheme based on ASTM E84 test results.