The Steiner Tunnel Test assesses which property of building materials?

• A. Flame spread
• B. Temperature resistance
• C. Structural integrity
• D. Water absorbency

Answer: (A)

The Steiner Tunnel Test measures how quickly flames spread across a material’s surface when exposed to a standardized fire. In practice, a specimen is placed in a long tunnel and a controlled flame is applied at one end; the distance the flames travel along the surface is recorded as the flame-spread index, with smoke development also measured. This test is used to classify interior finish materials for fire-code purposes, focusing on surface flame propagation rather than how much heat the material can withstand (temperature resistance), whether it maintains structural integrity under fire, or how much water the material absorbs.