For Fire Officials
All insulations must meet ASTM E 84 fire standards, and our Cel-Pak cellulose has a Class A rating. But even for materials that meet that standard, there's room for wide variation in real world performance.
Glass fiber is a Class A rated insulation, but at temperatures likely to be encountered in a structural fire, it melts, which can expose framing and sheathing, and may allow a fire to spread rapidly.
Foam insulations must be covered with a thermal barrier, 15-minute fire resistant material. When that barrier is breached and sprayed foam insulations are exposed to flame, they produce large volumes of toxic and combustible smoke.
Among all the insulation products in common use, only cellulose offers an ASTM E 84 Smoke Developed Index between 0 and 5. Exposed to fire, cellulose produces negligible amounts of smoke, a major contributor to the potential for loss of life in a structural fire. In addition, cellulose requires no flammable paper or plastic vapor retarders.
How Cellulose performs in a fire
When exposed to fire, the surface of a Cel-Pak insulated cavity immediately chars, effectively protecting what's beneath it. Cellulose is so effective, it actually performs as an ICC approved fire block material and as an ignition barrier over spray foam. Take a look at this flame test video, and this one where we melt a copper slug.