Loose fill Insulation

The fire resistive time period for concrete masonry units meeting the equivalent thickness required for a two-hour-fire-resistive rating in Item 6 (below) and having a thickness of not less than 7 5/8 inches is four hours when cores which are not grouted are filled with silicone-treated perlite loose-fill insulation; vermiculite loose-fill insulation; or expanded clay, shale or slate lightweight aggregate, sand or slag having a maximum particle size of 3/8 inches. (Table 7-B, Footnote 16)