What classification is assigned to an interior wall and ceiling finish with a flame spread index of 38?

The classification of interior wall and ceiling finishes is determined by their flame spread index, which is a measure of how quickly flames spread across a material's surface. According to the National Fire Protection Association (NFPA) standards, finishes are categorized into classifications based on their flame spread index values.

Class A finishes have the highest fire resistance, with a flame spread index of 0 to 25, indicating very low flame spread. Class B finishes have a flame spread index of 26 to 75, signifying that they can exhibit moderate flame spread characteristics. In contrast, Class C finishes fall within the range of 76 to 200, indicating a higher flame spread potential.

Given a flame spread index of 38, the interior wall and ceiling finish corresponds to the Class B category. This classification is crucial for fire safety, as it informs building design and material selection, influencing how interiors respond in the event of a fire. A finish with a flame spread index of 38 indicates it has moderate fire resistance, which is suitable for specific applications but requires correct placement within a building's overall fire safety strategy.