Fire Safety

Cellulose Insulation Aces Fire Tests

Fire Testing Shows Cellulose Helps Make Homes Safer
New tests add to the growing evidence that cellulose insulation increases the fire resistance of building assemblies. Omega Point Laboratories conducted full-scale tests on several types of wall assemblies, with the cellulose insulated wall sections proving to be up to 77% more fire resistant than uninsulated sections. Based on the test data, the laboratory reported:
“The results from this test have shown that when cellulose insulation is installed in the stud cavity of a wood stud/gypsum wallboard wall assembly, the fire resistance is increased significantly when compared to an uninsulated wall.”

Some sections of the test walls were constructed with 1/2-inch type X gypsum board and others with 5/8-inch type X board. All wall sections were tested using the ASTM E119-98 procedures. As shown in Figure 1, the cellulose insulation walls were much more fire resistant. Uninsulated wall sections failed in 53 to 60 minutes. Cellulose insulated wall sections failed in 76 minutes to no failure (11 of the 25 thermocouples on the cellulose insulated sections never failed during the 94 minute test). Impressive Results = Code Changes

The test results are especially impressive because the wall integrity was compromised by installing 16 steel electrical outlet boxes, 8 on each side of the wall. Despite this, the cellulose insulation performed so well that members of the International Code Council have agreed to make an exception to their design requirements for one-hour rated walls - often called “common walls” or “party walls”. For cellulose insulated one-hour walls, steel electrical boxes on opposite sides of the wall can be installed in the same stud cavity as long as cellulose insulation separates them! (The cellulose between the boxes must be at least as thick as the depth of the wall cavity.)

For fiberglass insulated one-hour walls, the new code forbids installing steel electrical boxes on opposite sides of the wall within the same stud cavity. Multiple Wall Configurations In a separate battery of tests, the National Fire Laboratory of the National Research Council of Canada, one of the world’s premier building material fire testing facilities, conducted fire resistance tests on wood and steel framed walls. The tests were performed on uninsulated, fiberglass insulated, and cellulose insulated walls (results in Figure 2).

The results were impressive:
the cellulose insulation consistently and significantly increased the fire resistance of the walls - by up to 71%! It seemed that no matter how the walls were built, cellulose helped make them safer. Many configurations put to the test: various types of studs, stud spacing, types of gypsum board, numbers of layers of gypsum, with and without resilient channel. Time after time, cellulose dramatically improved the fire safety. Floors Too! Another research project determined that cellulose can help make floors safer, too! The Institute for Research in Construction showed that floor assemblies can be built to achieve improved acoustic isolation and better fire resistance. To quote from the report: “In assemblies with solid wood joists and a single layer of bypsum board, glass fiber insulation reduced the fire resistance because it melted quickly...” In similar assemblies with cellulose fiber insulation, “fire resistance increased, because the insulation stayed in place longer...” The denser “cellulose fiber products also gave a slightly higher sound isolation than the glass fiber.”