What is the flame spread index for insulation materials as per building standards?

The flame spread index is a crucial metric used to evaluate the fire safety characteristics of building materials, particularly insulation. For insulation materials, a flame spread index of 25 indicates that the material has a moderate level of combustibility.

According to building standards, materials with a flame spread index of 25 or less are typically permitted in certain applications, ensuring that they can withstand fire exposure without supporting excessive flame spread. This classification helps ensure that the materials used in construction contribute to overall fire safety, allowing for adequate time for evacuation and minimizing the risk of fire spreading quickly through a structure.

Conversely, a flame spread index of 0 would indicate non-combustible materials, while indices of 15 or lower generally pertain to materials that demonstrate better fire-resistant properties. An index of 50, however, would signify greater combustibility and a higher potential for rapid flame spread, which is less desirable in insulation materials.

Therefore, a flame spread index of 25 reflects a balance that aligns with safety standards for insulation materials, making it the correct choice.