Firewalls / Permanency

Firewall Tests

As the firewall test results demonstrate, the dense structure of cellulose and its fire retardants slow the spread of fire through a building by blocking flames and hot gases and restricting the availability of oxygen in insulated walls and ceilings. Scientists at the National Research Council Canada report that "cellulose in the wall cavity provided an increase in the fire resistance performance of 22% to 55%." Fire roars right through conventional insulation. The NRCC study showed that "the fire resistance of an assembly with glass fiber insulation was slightly lower than that of a non-insulated assembly."

Furnace temperatures in
excess of 1800 degrees.


Exposed surface after
removal from furnace

Maximum average temperature
of unexposed surface: 138 degrees.


End of hose stream test –
unexposed surface still intact.

Fire Retardant Permanency

Fire Retardants used in Nu-Wool Cellulose Insulation do not lose their effectiveness over time. Tests by scientists and technicians at Oak Ridge National Laboratory, Tennessee Technological University, Allied Signal corp., US Borax Corp., Underwriters Laboratories, and United States Testing Company, found no sign of "disappearing fire retardants."