DIRECT WITHDRAWAL AND HEAD PULL-THROUGH PERFORMANCE OF NAILS AND STAPLES IN STRUCTURAL WOOD-BASED PANEL MATERIALS.

In both the nail and staple direct withdrawal resistance tests, 1/2-inch thick waferboard and two OSBs performed equal to or better than CD-grade plywood sheathing in all three exposures, but the veneered composites performed as well as plywood only in the dry and 24-hour soaked conditions. The ASTM 24-hour soaking and 6-cycle accelerated-aging exposures reduced the average nail withdrawal resistance value in roof sheathing specimens about 30 and 40 percent, respectively; and reduced the staple withdrawal resistance about 55 and 8 percent, respectively. The staples showed higher withdrawal resistance values than the nails in the dry and 24-hour water-soaked conditions, while nails showed much better results in the 6-cycle accelerated-aged condition. The newly developed nailhead push-through test appears to be a good substitution for the ASTM nailhead pull-through method.