Insulating materials, where exposed as installed in buildings of any type of construction, shall have a flame spread index of not more than 25 and a smoke-developed index of not more than 450.
Exception: Cellulose loose-fill insulation that is not spray applied complying with the requirements of Section 720.6 shall only be required to meet the smoke-developed index of not more than 450.
Exposed insulation materials installed on attic floors shall have a critical radiant flux of not less than 0.12 watt per square centimeter when tested in accordance with ASTM E 970.