What is the maximum flame spread index allowed for thermal and acoustical insulation in Type I or II construction?

The maximum flame spread index allowed for thermal and acoustical insulation in Type I or II construction is set at 25. This limit is established to ensure that the materials used in these types of construction are able to resist combustion and limit the spread of flames, thereby enhancing the overall safety of the building.

Type I and II constructions typically involve non-combustible materials, and maintaining a flame spread index of 25 for insulation helps to meet the stringent fire safety requirements associated with these building types. The flame spread index is a critical factor in evaluating the fire performance of building materials, and an index of 25 indicates that while the material is still combustible, it will not ignite and spread flames quickly, allowing for a greater margin of safety in case of a fire outbreak.

Understanding this standard is essential for inspections and ensuring compliance with building codes designed to protect occupants and property.