Loose Fill Material

If the cells of hollow unit masonry are filled with approved material, the equivalent thickness of the assembly can be considered the same as actual thickness. The list of approved materials includes: sand, pea gravel, crushed stone, or slag that meets ASTM C33 requirements; pumice, scoria, expanded shale, expanded clay, expanded slate, expanded slag, expanded flyash, or cinders that comply with ASTM C331 or C332, or perlite or vermiculate meeting the requirements of ASTM C549 and C516 respectively.