Originally Posted By: Susan
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The IRC (I have the 2000 as that is what I inspect under in my jurisdiction) discusses required fireblocking and materials and unfaced fiberglass in section R602.8.
Here's the Materials section (R602.8.1)
Except as provided in Section R602.8, Item 4, fireblocking shall consist of 2 inch nominal lumber, or two thicknesses of 1 inch nominal lumber with broken lap joints, or one thickness of 23/32 inch wood structural panels with joints backed by 23/32 inch wood structural panels or one thickness of 3/4 inch particleboard with joints backed by 3/4 inch particleboard, 1/2 inch gypsum board, or 1/4 inch cement based millboard. Batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place shall be permitted as an acceptable fire block. Loose fill insulation material shall not be used as a fire block unless specifically tested in the form and manner intended for use to demonstrate its ability to remain in place and to retard the spread of fire and hot gases.
R602.8.1.1 Unfaced fiberglass. Unfaced fiberglass batt insulation used as fireblocking shall fill the entire cross section of the wall cavity to a minimum height of 16 inches measured vertically. When piping, conduit or similar obstructions are encountered, the insulation shall be packed tightly around the obstruction.
Most materials (as an example, the spray foam, fire caulks, etc.) have a U.L. number and smoke/flame number on the container.
Hope this helps some....